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A systematic review of severe morbidity in infants born late preterm

      Objective

      Late-preterm infants (34 weeks 0/7 days-36 weeks 6/7 days' gestation) represent the largest proportion of singleton preterm births. A systematic review was performed to access the short- and/or long-term morbidity of late-preterm infants.

      Study Design

      An electronic search was conducted for cohort studies published from January 2000 through July 2010.

      Results

      We identified 22 studies studying 29,375,675 infants. Compared with infants born at term, infants born late preterm were more likely to suffer poorer short-term outcomes such as respiratory distress syndrome (relative risk [RR], 17.3), intraventricular hemorrhage (RR, 4.9), and death <28 days (RR, 5.9). Beyond the neonatal period, late-preterm infants were more likely to die in the first year (RR, 3.7) and to suffer from cerebral palsy (RR, 3.1).

      Conclusion

      Although the absolute incidence of neonatal mortality and morbidity in infants born late preterm is low, its incidence is significantly increased as compared with infants born at term.

      Key words

      The incidence of preterm birth, defined as delivery before the end of the 37th week (259th day) of pregnancy from the first day of the last menstrual period, is increasing. In the United States, the preterm rate rose from 9.1% in 1981 to 12.3% in 2003.
      • Raju T.N.
      • Higgins R.D.
      • Stark A.R.
      • Leveno K.J.
      Optimizing care and outcome for late-preterm (near-term) infants: a summary of the workshop sponsored by the National Institute of Child Health and Human Development.
      In certain regions in Brazil the prevalence of preterm birth was 15% according to the 2004 Pelotas birth cohort, roughly 3 times the prevalence found in the 1982 birth cohort in the same city.
      • Santos I.S.
      • Matijasevich A.
      • Silveira M.F.
      • et al.
      Associated factors and consequences of late preterm births: results from the 2004 Pelotas birth cohort.
      For Editors' Commentary, see Table of Contents
      Infants born between the gestational ages of 34 weeks and 0/7 days through 36 weeks and 6/7 days (239th-259th day) are called near term or late preterm.
      • Raju T.N.
      • Higgins R.D.
      • Stark A.R.
      • Leveno K.J.
      Optimizing care and outcome for late-preterm (near-term) infants: a summary of the workshop sponsored by the National Institute of Child Health and Human Development.
      Late-preterm infants account for about 74% of all preterm births and about 8% of all births. They are recognized as the fastest-increasing and largest proportion of singleton preterm births.
      • Davidoff M.J.
      • Dias T.
      • Damus K.
      • et al.
      Changes in the gestational age distribution among US singleton births: impact on rates of late preterm birth, 1992 to 2002.
      This increase might be due to a perception that electively delivered late-preterm babies face few risks.
      • Mateus J.
      • Fox K.
      • Jain S.
      • Jain S.
      • Latta R.
      • Cohen J.
      Preterm premature rupture of membranes: clinical outcomes of late-preterm infants.
      Several recent studies of late-preterm infants have documented increased short-term medical risks during their birth hospitalizations and increased adverse long-term outcomes (medical, social, behavior, school performance) compared to full-term infants.
      • Morse S.B.
      • Zheng H.
      • Tang Y.
      • Roth J.
      Early school-age outcomes of late preterm infants.
      Nevertheless, short- and long-term outcomes of late-preterm infants are not as frequently described as the outcomes of extremely preterm newborns and infants born late preterm are usually not entered in long-term developmental follow-up programs.
      • Kirkegaard I.
      • Obel C.
      • Hedegaard M.
      • Henriksen T.B.
      Gestational age and birth weight in relation to school performance of 10-year-old children: a follow-up study of children born after 32 completed weeks.
      • Moster D.
      • Lie R.T.
      • Markestad T.
      Long-term medical and social consequences of preterm birth.
      The aim of the current study was to perform a systematic review of the literature for medical and developmental short- and long-term outcomes of late-preterm infants to describe morbidity associated with late-preterm birth.

      Materials and Methods

      Search strategy

      We performed an electronic search in PubMed, MEDLINE, Embase, and Cochrane trials databases (inception from January 2000 through July 2010) for original (cohort) studies that reported on short-term and/or long-term outcomes of infants born late preterm. The search parameters we used were “34 weeks” or “35 weeks” or “36 weeks” and “late preterm” or “near term” and “complications” or “morbidity” or “outcome.” To be included, a study had to report on the short- and/or long-term outcomes of late-preterm infants (34-36 weeks 6/7 days) compared to full-term infants (≥37 weeks). Reference lists of known articles were checked to identify cited articles not captured by electronic searches. Review articles were also excluded but their reference lists were screened for relevant studies. Cohort studies reporting on <50 infants were excluded. There were no language restrictions.

      Data extraction

      The following data were extracted from included articles: author, year of publication, methodological characteristics of each study, sample size, and short- and/or long-term outcomes. Short-term outcomes included neonatal outcomes such as Apgar score, need for mechanical ventilation or intubation, nasal continuous positive airway pressure, use of nasal oxygen, use of surfactant, presence of transient tachypnea, respiratory distress syndrome, persistent pulmonary hypertension, apnea, pneumothorax, pneumonia, meningitis, sepsis, hypoglycemia, feeding problems, hypothermia, hyperbilirubinemia, jaundice requiring phototherapy, and neonatal death. Long-term outcomes incorporated complications such as neurological morbidity, school performance, growth, and social outcomes. All articles were scored independently by 2 reviewers; disagreement was resolved by consensus or by a third reviewer.

      Statistical analysis

      All extracted information was systematically recorded in a database, in which we classified methodological characteristics of each study and their outcomes. For each outcome, we calculated the absolute risk (AR) of neonatal outcome and relative risk (RR) with corresponding 95% confidence intervals (CIs). Heterogeneity was explored by Cochrane Q2 test and I2. I2 can be interpreted as the proportion of total variation observed between the trials attributable to differences between trials rather than sampling error (chance).
      • Higgins J.P.
      • Thompson S.G.
      Quantifying heterogeneity in a meta-analysis.
      I2 >75% is considered as a heterogeneous metaanalysis. We used a random effects model for pooling RR. Review Manager 5.0 (The Cochrane Collaboration, 2008; www.cochrane.org) was used to calculate these pooled effect estimates (RR and 95% CI).

      Results

      The results of the search strategy are shown in Figure 1. The electronic search detected 314 articles of which 48 were selected for full reading after studying the abstract. From these 48 articles, 8 studies were excluded because there was no full-term comparison group included.
      • Mateus J.
      • Fox K.
      • Jain S.
      • Jain S.
      • Latta R.
      • Cohen J.
      Preterm premature rupture of membranes: clinical outcomes of late-preterm infants.
      • Burke C.
      • Morrison J.J.
      Perinatal factors and preterm delivery in an Irish obstetric population.
      • Champion V.
      • Durrmeyer X.
      • Dassieu G.
      Short-term respiratory outcome of late preterm newborn in a center of level III [in French].
      • Cohen-Wolkowiez M.
      • Moran C.
      • Benjamin D.K.
      • et al.
      Early and late onset sepsis in late preterm infants.
      • Kalia J.L.
      • Visintainer P.
      • Brumberg H.L.
      • Pici M.
      • Kase J.
      Comparison of enrollment in interventional therapies between late-preterm and very preterm infants at 12 months' corrected age.
      • Kramer M.S.
      • Demissie K.
      • Yang H.
      • Platt R.W.
      • Sauve R.
      • Liston R.
      The contribution of mild and moderate preterm birth to infant mortality: Fetal and Infant Health Study Group of the Canadian Perinatal Surveillance System.
      • Malloy M.H.
      Impact of cesarean section on intermediate and late preterm births: United States, 2000-2003.
      • Vachharajani A.J.
      • Dawson J.G.
      Short-term outcomes of late preterms: an institutional experience.
      Six studies were excluded because they included infants born <34 weeks of gestation in their analysis.
      • Kirkegaard I.
      • Obel C.
      • Hedegaard M.
      • Henriksen T.B.
      Gestational age and birth weight in relation to school performance of 10-year-old children: a follow-up study of children born after 32 completed weeks.
      • Khashu M.
      • Narayanan M.
      • Bhargava S.
      • Osiovich H.
      Perinatal outcomes associated with preterm birth at 33 to 36 weeks' gestation: a population-based cohort study.
      • Lindstrom K.
      • Winbladh B.
      • Haglund B.
      • Hjern A.
      Preterm infants as young adults: a Swedish national cohort study.
      • Romeo D.M.
      • Di S.A.
      • Conversano M.
      • et al.
      Neurodevelopmental outcome at 12 and 18 months in late preterm infants.
      • Swamy G.K.
      • Ostbye T.
      • Skjaerven R.
      Association of preterm birth with long-term survival, reproduction, and next-generation preterm birth.
      • van Baar A.L.
      • Vermaas J.
      • Knots E.
      • de Kleine M.J.
      • Soons P.
      Functioning at school age of moderately preterm children born at 32 to 36 weeks' gestational age.
      Twenty studies were excluded for other reasons (eg, studies reporting on <50 infants, review articles, not possible to make 2×2 tables). From references in selected articles and identified reviews, another 8 articles were included. Thus, 22 articles were available for the final review. These 22 studies included in total 2,368,471 late-preterm infants and 27,007,204 term infants.
      • Santos I.S.
      • Matijasevich A.
      • Silveira M.F.
      • et al.
      Associated factors and consequences of late preterm births: results from the 2004 Pelotas birth cohort.
      • Morse S.B.
      • Zheng H.
      • Tang Y.
      • Roth J.
      Early school-age outcomes of late preterm infants.
      • Moster D.
      • Lie R.T.
      • Markestad T.
      Long-term medical and social consequences of preterm birth.
      • Baron I.S.
      • Erickson K.
      • Ahronovich M.D.
      • Coulehan K.
      • Baker R.
      • Litman F.R.
      Visuospatial and verbal fluency relative deficits in 'complicated' late-preterm preschool children.
      • Bastek J.A.
      • Sammel M.D.
      • Pare E.
      • Srinivas S.K.
      • Posencheg M.A.
      • Elovitz M.A.
      Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.
      • Chyi L.J.
      • Lee H.C.
      • Hintz S.R.
      • Gould J.B.
      • Sutcliffe T.L.
      School outcomes of late preterm infants: special needs and challenges for infants born at 32 to 36 weeks gestation.
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • Gurka M.J.
      • LoCasale-Crouch J.
      • Blackman J.A.
      Long-term cognition, achievement, socioemotional, and behavioral development of healthy late-preterm infants.
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      • Kitsommart R.
      • Janes M.
      • Mahajan V.
      • et al.
      Outcomes of late-preterm infants: a retrospective, single-center, Canadian study.
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • Ma X.
      • Huang C.
      • Lou S.
      • et al.
      The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Petrini J.R.
      • Dias T.
      • McCormick M.C.
      • Massolo M.L.
      • Green N.S.
      • Escobar G.J.
      Increased risk of adverse neurological development for late preterm infants.
      • Pulver L.S.
      • Guest-Warnick G.
      • Stoddard G.J.
      • Byington C.L.
      • Young P.C.
      Weight for gestational age affects the mortality of late preterm infants.
      • Santos I.S.
      • Matijasevich A.
      • Domingues M.R.
      • Barros A.J.
      • Victora C.G.
      • Barros F.C.
      Late preterm birth is a risk factor for growth faltering in early childhood: a cohort study.
      • Tomashek K.M.
      • Shapiro-Mendoza C.K.
      • Davidoff M.J.
      • Petrini J.R.
      Differences in mortality between late-preterm and term singleton infants in the United States, 1995-2002.
      • Wang M.L.
      • Dorer D.J.
      • Fleming M.P.
      • Catlin E.A.
      Clinical outcomes of near-term infants.
      • Yoder B.A.
      • Gordon M.C.
      • Barth Jr, W.H.
      Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
      • Young P.C.
      • Glasgow T.S.
      • Li X.
      • Guest-Warnick G.
      • Stoddard G.
      Mortality of late-preterm (near-term) newborns in Utah.
      The results of these 22 studies were used to calculate pooled RR and 95% CI if possible. For some outcomes high values of I2 (>75%) were found when calculating pooled RR. Nevertheless, almost all studies reporting on a specific outcome showed the same direction of effect (RR, >1). Characteristics of the included studies are presented in Table 1.
      Figure thumbnail gr1
      FIGURE 1Flow diagram of search outcomes
      GA, gestational age.
      Teune. Short- and long-term morbidity in late-preterm infants. Am J Obstet Gynecol 2011.
      TABLE 1Study characteristics
      Study IDAuthorYearNo. of LPINo. of FTIOutcomesGA LPI (wk d/d)GA FTI (wk d/d)Study designData collectionExclusion of infants with congenital anomalies
      1Wang et al
      • Wang M.L.
      • Dorer D.J.
      • Fleming M.P.
      • Catlin E.A.
      Clinical outcomes of near-term infants.
      20049095Short term35 0/7-36 6/737 0/7-40 6/7CohortRetrospectiveYes
      2Bastek et al
      • Bastek J.A.
      • Sammel M.D.
      • Pare E.
      • Srinivas S.K.
      • Posencheg M.A.
      • Elovitz M.A.
      Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.
      200869134Short term34 0/7-36 6/7≥37CohortRetrospectiveYes
      3McIntire et al
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      200821,77180,014Short term34 0/7-36 6/737 0/7-39 6/7CohortRetrospectiveYes
      4Yoder et al
      • Yoder B.A.
      • Gordon M.C.
      • Barth Jr, W.H.
      Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
      200889512,905Short term34 0/7-36 6/737 0/7-40 6/7CohortRetrospectiveNo
      5Guasch et al
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      2009200332,015Short term34 0/7-36 6/737 0/7-42 6/7CohortRetrospectiveNo
      6Kalyoncu et al
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      2010252252Short term34 0/7-36 6/737 0/7-41 6/7CohortRetrospectiveYes
      7Kitsommart et al
      • Kitsommart R.
      • Janes M.
      • Mahajan V.
      • et al.
      Outcomes of late-preterm infants: a retrospective, single-center, Canadian study.
      200911938666Short term34 0/7-36 6/7≥37CohortRetrospectiveNo
      8Lubow et al
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      2009149150Short term34 0/7-36 6/737 0/7-41 6/7CohortRetrospectiveNo
      9Ma et al
      • Ma X.
      • Huang C.
      • Lou S.
      • et al.
      The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
      200920326867Short term34 0/7-36 6/7≥37CohortProspectiveNo
      10Melamed et al
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      200924787434Short term34 0/7-36 6/737 0/7-40 0/7CohortRetrospectiveYes
      11Hibbard et al
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      201019,334165,993Short term34 0/7-36 6/737 0/7-40 6/7CohortRetrospectiveNo
      12Tomashek et al
      • Tomashek K.M.
      • Shapiro-Mendoza C.K.
      • Davidoff M.J.
      • Petrini J.R.
      Differences in mortality between late-preterm and term singleton infants in the United States, 1995-2002.
      20072,221,54524,973,117Short term + 12 mo34 0/7-36 6/737 0/7-41 6/7CohortRetrospectiveNo
      13Young et al
      • Young P.C.
      • Glasgow T.S.
      • Li X.
      • Guest-Warnick G.
      • Stoddard G.
      Mortality of late-preterm (near-term) newborns in Utah.
      200721,106247,43312 mo34 0/7-36 6/737 0/7-40 6/7CohortRetrospectiveNo
      14Santos et al
      • Santos I.S.
      • Matijasevich A.
      • Silveira M.F.
      • et al.
      Associated factors and consequences of late preterm births: results from the 2004 Pelotas birth cohort.
      20084473262Short term until 3 mo34 0/7-36 6/737 0/7-41 6/7CohortProspectiveNo
      15Chyi et al
      • Chyi L.J.
      • Lee H.C.
      • Hintz S.R.
      • Gould J.B.
      • Sutcliffe T.L.
      School outcomes of late preterm infants: special needs and challenges for infants born at 32 to 36 weeks gestation.
      200897013,671Fifth grade34 0/7-36 6/7≥37CohortRetrospectiveNo
      16Moster et al
      • Moster D.
      • Lie R.T.
      • Markestad T.
      Long-term medical and social consequences of preterm birth.
      200832,187853,30920-36 y34 0/7-36 6/7≥37CohortProspectiveYes
      17Pulver et al
      • Pulver L.S.
      • Guest-Warnick G.
      • Stoddard G.J.
      • Byington C.L.
      • Young P.C.
      Weight for gestational age affects the mortality of late preterm infants.
      200925,973316,077Short term + 12 mo34 0/7-36 6/737 0/7-41 6/7CohortRetrospectiveNo
      18Santos et al
      • Santos I.S.
      • Matijasevich A.
      • Domingues M.R.
      • Barros A.J.
      • Victora C.G.
      • Barros F.C.
      Late preterm birth is a risk factor for growth faltering in early childhood: a cohort study.
      2009371291412 and 24 mo34 0/7-36 6/737 0/7-42 6/7CohortProspectiveNo
      19Baron et al
      • Baron I.S.
      • Erickson K.
      • Ahronovich M.D.
      • Coulehan K.
      • Baker R.
      • Litman F.R.
      Visuospatial and verbal fluency relative deficits in 'complicated' late-preterm preschool children.
      20096035Short term + 3 y34 0/7-36 6/7≥37CohortRetrospectiveYes
      20Morse et al
      • Morse S.B.
      • Zheng H.
      • Tang Y.
      • Roth J.
      Early school-age outcomes of late preterm infants.
      20097152152,6613-5 y34 0/7-36 6/737 0/7-41 6/7CohortRetrospectiveYes
      21Gurka et al
      • Gurka M.J.
      • LoCasale-Crouch J.
      • Blackman J.A.
      Long-term cognition, achievement, socioemotional, and behavioral development of healthy late-preterm infants.
      201053124515 y34 0/7-36 6/737 0/7-41 6/7CohortProspectiveYes
      22Petrini et al
      • Petrini J.R.
      • Dias T.
      • McCormick M.C.
      • Massolo M.L.
      • Green N.S.
      • Escobar G.J.
      Increased risk of adverse neurological development for late preterm infants.
      20098341128,955Short term + 5.5 y34 0/7-36 6/737 0/7-41 6/7CohortRetrospectiveNo
      FTI, full-term infant; GA, gestational age; LPI, late-preterm infant.
      Teune. Short- and long-term morbidity in late-preterm infants. Am J Obstet Gynecol 2011.

      Short-term outcomes

      Table 2 shows the short-term outcomes of late-preterm infants compared to term infants. Late-preterm infants were more likely to suffer poorer short-term outcomes. The incidence rate was higher for late-preterm infants in 26 of the 27 short-term outcomes; 23 of these outcomes were significant (Table 2). Late-preterm infants had higher rates for neonatal death (0-28 days) than term infants (RR, 5.9; 95% CI, 5.0–6.9) with an AR of 0.38% vs 0.07% (Figure 2) . They were more likely to need mechanical ventilation (RR, 4.9; 95% CI, 2.8–8.6; AR, 2.5% vs 1.2%) or to suffer from respiratory distress syndrome (RR, 17.3; 95% CI, 9.8–30.6; AR, 5.3% vs 0.39%). Furthermore, they suffered more often from necrotizing enterocolitis (OR, 7.5; 95% CI, 3.3–17.3; AR, 0.11% vs 0.007%) and intraventricular hemorrhage occurred more often in late-preterm infants (OR, 4.9; 95% CI, 2.1–11.7; AR, 0.41% vs 0.09%). Table 3 shows the short-term outcomes of late-preterm infants by week of gestation compared to term infants for those studies that included such data. The shorter the term of pregnancy, the higher the risk was for neonatal morbidity and mortality.
      TABLE 2Short-term outcomes of infants born late preterm compared to full-term infants
      VariableLate-preterm infants, n (AR%)Full-term infants, n (AR%)Random effects model Pooled RR (95% CI)I2
      34-37 wk>37 wk34-37 wk
      Mortality
       Neonatal (0-28 d)
      • Santos I.S.
      • Matijasevich A.
      • Silveira M.F.
      • et al.
      Associated factors and consequences of late preterm births: results from the 2004 Pelotas birth cohort.
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      • Kitsommart R.
      • Janes M.
      • Mahajan V.
      • et al.
      Outcomes of late-preterm infants: a retrospective, single-center, Canadian study.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Pulver L.S.
      • Guest-Warnick G.
      • Stoddard G.J.
      • Byington C.L.
      • Young P.C.
      Weight for gestational age affects the mortality of late preterm infants.
      • Young P.C.
      • Glasgow T.S.
      • Li X.
      • Guest-Warnick G.
      • Stoddard G.
      Mortality of late-preterm (near-term) newborns in Utah.
      356/94,557 (0.38%)622/892,383 (0.07%)5.9 (5.0–6.9)16%
       Apgar score at 5 min ≤3
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      27/21,772 (0.12%)75/111,251 (0.07%)1.8 (1.2–2.9)NA
       Apgar score at 5 min <7
      • Santos I.S.
      • Matijasevich A.
      • Silveira M.F.
      • et al.
      Associated factors and consequences of late preterm births: results from the 2004 Pelotas birth cohort.
      • Lindstrom K.
      • Winbladh B.
      • Haglund B.
      • Hjern A.
      Preterm infants as young adults: a Swedish national cohort study.
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Petrini J.R.
      • Dias T.
      • McCormick M.C.
      • Massolo M.L.
      • Green N.S.
      • Escobar G.J.
      Increased risk of adverse neurological development for late preterm infants.
      751/28,122 (2.7%)2889/298,210 (0.97%)2.7 (1.7–4.4)95%
      Respiratory morbidity
       Mechanical ventilation or endotracheal intubation
      • Morse S.B.
      • Zheng H.
      • Tang Y.
      • Roth J.
      Early school-age outcomes of late preterm infants.
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      • Kitsommart R.
      • Janes M.
      • Mahajan V.
      • et al.
      Outcomes of late-preterm infants: a retrospective, single-center, Canadian study.
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • Ma X.
      • Huang C.
      • Lou S.
      • et al.
      The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Wang M.L.
      • Dorer D.J.
      • Fleming M.P.
      • Catlin E.A.
      Clinical outcomes of near-term infants.
      916/37,119 (2.5%)3762/319,491 (1.2%)4.9 (2.8–8.6)97%
       Nasal CPAP
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      • Kitsommart R.
      • Janes M.
      • Mahajan V.
      • et al.
      Outcomes of late-preterm infants: a retrospective, single-center, Canadian study.
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • Ma X.
      • Huang C.
      • Lou S.
      • et al.
      The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      1518/27,441 (5.5%)912/221,477 (0.41%)9.8 (5.1–18.8)98%
       Use of nasal oxygen
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      1164/19,473 (6.0%)849/166,228 (0.51%)24.4 (5.1–116.1)96%
       Use of surfactant
      • Bastek J.A.
      • Sammel M.D.
      • Pare E.
      • Srinivas S.K.
      • Posencheg M.A.
      • Elovitz M.A.
      Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      735/19,403 (3.8%)378/166,127 (0.23%)16.6 (14.7–18.8)0%
       TTN
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • Ma X.
      • Huang C.
      • Lou S.
      • et al.
      The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Yoder B.A.
      • Gordon M.C.
      • Barth Jr, W.H.
      Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
      1688/48,663 (3.5%)1526/336,715 (0.45%)7.5 (5.0–11.2)96%
       RDS
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • Ma X.
      • Huang C.
      • Lou S.
      • et al.
      The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Yoder B.A.
      • Gordon M.C.
      • Barth Jr, W.H.
      Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
      1325/24,888 (5.3%)749/193,449 (0.39%)17.3 (9.8–30.6)91%
       PPH
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Yoder B.A.
      • Gordon M.C.
      • Barth Jr, W.H.
      Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
      90/22,707 (0.40%)164/196,332 (0.08%)4.9 (3.8–6.3)0%
       Apnea
      • Bastek J.A.
      • Sammel M.D.
      • Pare E.
      • Srinivas S.K.
      • Posencheg M.A.
      • Elovitz M.A.
      Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Wang M.L.
      • Dorer D.J.
      • Fleming M.P.
      • Catlin E.A.
      Clinical outcomes of near-term infants.
      211/24,226 (0.87%)104/205,923 (0.05%)15.7 (11.8–20.9)13%
       Pneumothorax
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Kitsommart R.
      • Janes M.
      • Mahajan V.
      • et al.
      Outcomes of late-preterm infants: a retrospective, single-center, Canadian study.
      • Ma X.
      • Huang C.
      • Lou S.
      • et al.
      The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Yoder B.A.
      • Gordon M.C.
      • Barth Jr, W.H.
      Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
      226/27,935 (0.81%)402/233,980 (0.17%)3.4 (1.8–6.4)90%
      Infectious morbidity
       Pneumonia
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Ma X.
      • Huang C.
      • Lou S.
      • et al.
      The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Yoder B.A.
      • Gordon M.C.
      • Barth Jr, W.H.
      Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
      547/24,739 (2.2%)1140/193,299 (0.59%)3.5 (1.4–8.9)98%
       Meningitis
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      3/2478 (0.12%)0/7434 (0%)21.0 (1.1–406.3)NA
       Sepsis workup
      • Santos I.S.
      • Matijasevich A.
      • Silveira M.F.
      • et al.
      Associated factors and consequences of late preterm births: results from the 2004 Pelotas birth cohort.
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Wang M.L.
      • Dorer D.J.
      • Fleming M.P.
      • Catlin E.A.
      Clinical outcomes of near-term infants.
      4877/24,755 (19.7%)14,075/119,316 (11.8%)4.2 (1.7–10.7)99%
       Sepsis (culture proven)
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      87/24,501 (0.36%)160/118,937 (0.13%)5.6 (1.3–24.2)76%
       NEC
      • Bastek J.A.
      • Sammel M.D.
      • Pare E.
      • Srinivas S.K.
      • Posencheg M.A.
      • Elovitz M.A.
      Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      27/24,750 (0.11%)8/119,071 (0.007%)7.5 (3.3–17.3)0%
      CNS morbidity
       Seizures/convulsions
      • Bastek J.A.
      • Sammel M.D.
      • Pare E.
      • Srinivas S.K.
      • Posencheg M.A.
      • Elovitz M.A.
      Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Petrini J.R.
      • Dias T.
      • McCormick M.C.
      • Massolo M.L.
      • Green N.S.
      • Escobar G.J.
      Increased risk of adverse neurological development for late preterm infants.
      22/10,888 (0.20%)169/136,563 (0.12%)1.6 (0.8–3.0)28%
       IVH (grade I-IV)
      • Bastek J.A.
      • Sammel M.D.
      • Pare E.
      • Srinivas S.K.
      • Posencheg M.A.
      • Elovitz M.A.
      Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.
      • Ma X.
      • Huang C.
      • Lou S.
      • et al.
      The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      108/26,350 (0.41%)114/125,786 (0.09%)4.9 (2.1–11.7)79%
       IVH (grade I-II)
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      42/24,249 (0.17%)24/118,685 (0.02%)8.4 (5.1–13.9)0%
       IVH (grade III-IV)
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      2/21,771 (0.01%)4/111,251 (0.004%)2.6 (0.5–14.0)NA
      Metabolic morbidity
       Hypoglycemia
      • Bastek J.A.
      • Sammel M.D.
      • Pare E.
      • Srinivas S.K.
      • Posencheg M.A.
      • Elovitz M.A.
      Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • Ma X.
      • Huang C.
      • Lou S.
      • et al.
      The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Wang M.L.
      • Dorer D.J.
      • Fleming M.P.
      • Catlin E.A.
      Clinical outcomes of near-term infants.
      504/7073 (7.1%)323/47,047 (0.69%)7.4 (3.0–18.1)96%
       Feeding problems
      • Bastek J.A.
      • Sammel M.D.
      • Pare E.
      • Srinivas S.K.
      • Posencheg M.A.
      • Elovitz M.A.
      Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • Wang M.L.
      • Dorer D.J.
      • Fleming M.P.
      • Catlin E.A.
      Clinical outcomes of near-term infants.
      200/588 (34.0%)42/631 (6.7%)6.5 (2.5–16.9)84%
       TPN
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      240/2255 (10.6%)63/32,267 (0.20%18.4 (13.5–25.0)0%
       Hypothermia
      • Bastek J.A.
      • Sammel M.D.
      • Pare E.
      • Srinivas S.K.
      • Posencheg M.A.
      • Elovitz M.A.
      Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.
      • Kalyoncu O.
      • Aygun C.
      • Cetinoglu E.
      • Kucukoduk S.
      Neonatal morbidity and mortality of late-preterm babies.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Wang M.L.
      • Dorer D.J.
      • Fleming M.P.
      • Catlin E.A.
      Clinical outcomes of near-term infants.
      44/2889 (1.5%)6/7915 (0.08%)10.8 (4.6–25.0)0%
       Hyperbilirubinemia
      • Bastek J.A.
      • Sammel M.D.
      • Pare E.
      • Srinivas S.K.
      • Posencheg M.A.
      • Elovitz M.A.
      Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • Ma X.
      • Huang C.
      • Lou S.
      • et al.
      The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
      • Wang M.L.
      • Dorer D.J.
      • Fleming M.P.
      • Catlin E.A.
      Clinical outcomes of near-term infants.
      422/2250 (18.8%)1931/7251 (26.7%)2.8 (0.51–15.3)97%
       Jaundice requiring phototherapy
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      1245/26,252 (4.7%)2033/150,700 (1.3%)5.0 (1.7–14.6)100%
      AR, absolute risk; CI, confidence interval; CNS, central nervous system; CPAP, continuous positive airway pressure; IVH, intraventricular hemorrhage; N/A, not applicable; NEC, necrotizing enterocolitis; PPH, persistent pulmonary hypertension; RDS, respiratory distress syndrome; RR, relative risk; TPN, total parental nutrition; TTN, transient tachypnea of newborn.
      Teune. Short- and long-term morbidity in late-preterm infants. Am J Obstet Gynecol 2011.
      Figure thumbnail gr2
      FIGURE 2Mortality 0-28 days (forest plot)
      CI, confidence interval.
      Teune. Short- and long-term morbidity in late-preterm infants. Am J Obstet Gynecol 2011.
      TABLE 3Short-term outcomes of late-preterm infants per week of gestation compared to term infants
      VariableLate-preterm infants, n (AR%)Full-term infants, n (AR%)Random effects model Pooled RR (95% CI)
      34 wk35 wk36 wk34 wk35 wk36 wk
      Mortality
       Neonatal (0-28 d)
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Pulver L.S.
      • Guest-Warnick G.
      • Stoddard G.J.
      • Byington C.L.
      • Young P.C.
      Weight for gestational age affects the mortality of late preterm infants.
      66/11,593 (0.57%)67/19,623 (0.34%)89/38,340 (0.23%)382/600,755 (0.06%)10.1 (7.0–14.4)6.3 (4.8–8.1)3.9 (2.7–5.7)
       Apgar score at 5 min ≤3
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      5/3498 (0.14%)12/6571 (0.18%)10/11,702 (0.09%)75/111,251 (0.07%)2.1 (0.86–5.2)2.7 (1.5–5.0)1.3 (0.66–2.5)
       Apgar score at 5 min <7NANANANANANANA
      Respiratory morbidity
       Mechanical ventilation or endotracheal intubation
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      143/3940 (3.6%)121/7239 (1.7%)104/13,219 (0.79%)421/118,83512.4 (3.6–42.4)5.3 (3.4–8.2)2.8 (1.3–6.0)
       Nasal CPAP
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      366/4142 (8.8%)327/6145 (5.3%)246/11,674 (2.1%)452/173,577 (0.26%)25.9 (14.7–45.8)16.4 (8.9–30.4)36 wk
       Use of nasal oxygen
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      357/3700 (9.6%)354/5477 (6.5%)340/10,157 (3.3%)832/165,993 (0.50%)19.3 (17.1–21.7)12.9 (11.4–14.6)6.7 (5.9–7.6)
       Use of surfactant
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      273/3700 (7.4%)237/5477 (4.3%)222/10,157 (2.2%)378/165,993 (0.23%)32.4 (27.8–37.7)19.0 (16.2–22.3)9.6 (8.2–11.3)
       TTN
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Yoder B.A.
      • Gordon M.C.
      • Barth Jr, W.H.
      Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
      397/7808 (5.1%)432/12,950 (3.3%)477/23,869 (2.0%)1040/297,733 (0.35%)15.4 (11.3–21.1)9.6 (7.9–11.8)5.7 (5.1–6.4)
       RDS
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Yoder B.A.
      • Gordon M.C.
      • Barth Jr, W.H.
      Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
      456/4310 (10.6%)383/6379 (6.0%)323/12,167 (2.7%)672/186,482 (0.36%)48.4 (18.6–126)28.6 (12.2–66.8)10.9 (5.9–20.4)
       PPH
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Yoder B.A.
      • Gordon M.C.
      • Barth Jr, W.H.
      Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
      5/561 (0.89%)3/852 (0.35%)1/1960 (0.05%)17/30,339 (0.06%)20.8 (7.7–56.1)10.3 (1.4–78.9)2.6 (0.35–18.6)
       Apnea
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      93/4405 (2.1%)49/6591 (0.74%)52/12,819 (0.41%)104/205,442 (0.05%)39.7 (22.5–70.1)14.9 (8.0–27.7)7.0 (4.9–9.9)
       Pneumothorax
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Yoder B.A.
      • Gordon M.C.
      • Barth Jr, W.H.
      Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
      34/4261 (0.80%)43/6329 (0.68%)79/12,117 (0.65%)188/186,332 (0.10%)8.0 (5.6–11.6)6.7 (4.8–9.4)6.3 (4.2–9.6)
      Infectious morbidity
       Pneumonia
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Yoder B.A.
      • Gordon M.C.
      • Barth Jr, W.H.
      Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
      59/4261 (1.4%)74/6329 (1.2%)76/12,117 (0.63%)336/186,332 (0.18%)8.0 (5.2–12.4)7.0 (3.8–12.8)3.7 (2.9–4.7)
       Meningitis
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      0/393 (0%)1/618 (0.16%)2/1467 (0.14%)0/7434 (0%)NA36.0 (1.5–884)25.3 (1.2–527)
       Sepsis workup
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      1231/3940 (31.2%)1592/7239 (22.0%)1962/13,219 (14.8%)14,054/118,835 (11.8%)7.1 (1.5–34.4)4.4 (1.02–18.6)2.1 (0.65–7.1)
       Sepsis (culture proven)
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      25/3891 (0.64%)24/7189 (0.33%)29/13,169 (0.22%)160/118,685 (0.13%)11.7 (1.02–134)2.5 (1.6–3.9)2.2 (0.78–6.0)
       NEC
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      8/3891 (0.21%)4/7189 (0.06%)3/13,169 (0.02%)8/118,685 (0.007%)23.7 (8.9–63.6)7.1 (2.1–24.4)2.5 (0.65–9.5)
      CNS morbidity
       Seizures/convulsions
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      2/393 (0.51%)2/618 (0.32%)6/1467 (0.41%)11/7434 (0.15%)3.4 (0.76–15.4)2.2 (0.49–9.9)2.8 (1.02–7.5)
       IVH (grade I-IV)
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      18/3891 (0.46%)16/7189 (0.22%)10/13,169 (0.08%)28/118,685 (0.02%)19.5 (10.8–35.3)9.4 (5.1–17.4)3.3 (1.6–7.0)
       IVH (grade I-II)
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      18/3891 (0.46%)15/7189 (0.21%)9/13,169 (0.07%)24/118,685 (0.02%)22.7 (12.3–41.8)10.2 (5.4–19.5)3.3 (1.5–7.2)
       IVH (grade III-IV)
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      0/3498 (0%)1/6571 (0.02%)1/11,702 (0.009%)4/111,251 (0.004%)3.5 (0.19–65.6)4.2 (0.47–37.9)2.4 (0.27–21.3)
      Metabolic morbidity
       Hypoglycemia
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      87/754 (11.5%)62/1164 (5.3%)120/2712 (4.4%)104/39,599 (0.26%)32.7 (13.5–79.2)15.3 (7.3–32.0)12.3 (9.2–16.4)
       Feeding problems
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      25/49 (51.0%)17/50 (34.0%)11/50 (22%)8/150 (5.3%)9.6 (4.6–19.8)6.4 (2.9–13.9)4.1 (1.8–9.7)
       TPN
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      28/312 (9.0%)18/496 (3.6%)17/1195 (1.4%)52/32,015 (0.16%)55.3 (35.4–86.3)22.3 (13.2–37.9)8.8 (5.1–15.1)
       Hypothermia
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      10/393 (2.5%)5/618 (0.81%)3/1467 (0.20%)5/7434 (0.07%)37.8 (13.0–110)12.0 (3.5–41.4)3.0 (0.73–12.7)
       Hyperbilirubinemia
      • Lubow J.M.
      • How H.Y.
      • Habli M.
      • Maxwell R.
      • Sibai B.M.
      Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
      21/49 (42.9%)8/50 (16.0%)8/50 (16.0%)4/150 (2.7%)16.1 (5.8–44.5)6.0 (1.9–19.1)6.0 (1.9–19.1)
       Jaundice requiring phototherapy
      • Guasch X.D.
      • Torrent F.R.
      • Martinez-Nadal S.
      • Ceren C.V.
      • Saco M.J.
      • Castellvi P.S.
      Late preterm infants: a population at underestimated risk [in Spanish].
      • McIntire D.D.
      • Leveno K.J.
      Neonatal mortality and morbidity rates in late preterm births compared with births at term.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      433/4203 (10.3%)463/7685 (6.0%)349/14,364 (2.4%)2033/150,700 (1.3%)10.6 (4.4–25.3)6.7 (2.7–16.2)2.0 (0.33–12.2)
      AR, absolute risk; CI, confidence interval; CNS, central nervous system; CPAP, continuous positive airway pressure; IVH, intraventricular hemorrhage; N/A, not applicable; NEC, necrotizing enterocolitis; PPH, persistent pulmonary hypertension; RDS, respiratory distress syndrome; RR, relative risk; TPN, total parental nutrition; TTN, transient tachypnea of newborn.
      Teune. Short- and long-term morbidity in late-preterm infants. Am J Obstet Gynecol 2011.

      Long-term outcomes

      Mortality

      Eleven studies reported on long-term outcomes of late-preterm infants. Infant death in the first year after delivery occurred 4 times more among children born late preterm (RR, 3.7; 95% CI, 2.9–4.6; AR, 0.83% vs 0.27%).
      • Santos I.S.
      • Matijasevich A.
      • Silveira M.F.
      • et al.
      Associated factors and consequences of late preterm births: results from the 2004 Pelotas birth cohort.
      • Khashu M.
      • Narayanan M.
      • Bhargava S.
      • Osiovich H.
      Perinatal outcomes associated with preterm birth at 33 to 36 weeks' gestation: a population-based cohort study.
      • Swamy G.K.
      • Ostbye T.
      • Skjaerven R.
      Association of preterm birth with long-term survival, reproduction, and next-generation preterm birth.
      • Melamed N.
      • Klinger G.
      • Tenenbaum-Gavish K.
      • et al.
      Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
      • Petrini J.R.
      • Dias T.
      • McCormick M.C.
      • Massolo M.L.
      • Green N.S.
      • Escobar G.J.
      Increased risk of adverse neurological development for late preterm infants.
      • Santos I.S.
      • Matijasevich A.
      • Domingues M.R.
      • Barros A.J.
      • Victora C.G.
      • Barros F.C.
      Late preterm birth is a risk factor for growth faltering in early childhood: a cohort study.
      In total, 2,269,071 late-preterm infants and 25,554,246 term infants were included in this analysis (Figure 3) .
      Figure thumbnail gr3
      FIGURE 3Mortality 0-365 days (forest plot)
      CI, confidence interval.
      Teune. Short- and long-term morbidity in late-preterm infants. Am J Obstet Gynecol 2011.

      Neurological development

      Four studies reported adverse neurological development in later life. Late-preterm infants (n = 40,416) were more likely to suffer from cerebral palsy than infants born at term (n = 981,154) (RR, 3.1; 95% CI, 2.3–4.2; AR 0.43% vs 0.14%) and late-preterm infants (n = 40,203) were more likely to develop mental retardation than infants born at term (n = 977,505) (RR, 1.5; 95% CI, 1.2–1.9; AR, 0.81% vs 0.49%).
      • Moster D.
      • Lie R.T.
      • Markestad T.
      Long-term medical and social consequences of preterm birth.
      • Young P.C.
      • Glasgow T.S.
      • Li X.
      • Guest-Warnick G.
      • Stoddard G.
      Mortality of late-preterm (near-term) newborns in Utah.
      One of these studies (32,126 late-preterm infants, 852,157 term infants) also reported an increased risk of developing schizophrenia (RR, 1.4; 95% CI, 1.1–1.8; AR, 0.19% vs 0.14%), but no increased risk of autism (RR, 0.72; 95% CI, 0.40–1.3; AR, 0.03% vs 0.05%) in late-preterm infants.
      • Moster D.
      • Lie R.T.
      • Markestad T.
      Long-term medical and social consequences of preterm birth.
      Furthermore, this study reported an increased risk for disorders related to psychological development, behavior, and emotion.
      • Moster D.
      • Lie R.T.
      • Markestad T.
      Long-term medical and social consequences of preterm birth.
      However, another study (53 late-preterm infants, 1245 term infants) comparing cognitive, achievement, socioemotional, and behavioral outcomes between late-preterm infants and term infants showed that late-preterm offspring have no real deficits as they mature.
      • Gurka M.J.
      • LoCasale-Crouch J.
      • Blackman J.A.
      Long-term cognition, achievement, socioemotional, and behavioral development of healthy late-preterm infants.
      A fourth study (60 late-preterm infants, 35 term infants) examined general cognition, attention/working memory, language, manual coordination/motor dexterity, and visuomotor and executive function in preschoolers born late preterm (34-36 weeks) who required neonatal intensive care unit admission compared to term-born participants. In this study late-preterm birth was associated with visuospatial, visuomotor, and executive function deficits, but not with attention/working memory, receptive or expressive language, nonverbal reasoning, or manual coordination/dexterity deficits.
      • Wang M.L.
      • Dorer D.J.
      • Fleming M.P.
      • Catlin E.A.
      Clinical outcomes of near-term infants.

      School performance

      Several studies reported school outcomes. One of these studies (7152 late-preterm infants, 152,661 term infants) compared prekindergarten and kindergarten outcomes among healthy late-preterm infants and healthy term infants at birth. This study suggested that healthy late-preterm infants compared with healthy term infants face a greater risk for developmental delay and school-related problems through the first 5 years of life (developmental delay/disability between 0-3 years: RR, 1.4; 95% CI, 1.3–1.6; not ready to start school at 4 years: RR, 1.2; 95% CI, 1.0–1.3; exceptional student education at 5 years: RR, 1.1; 95% CI, 1.1–1.2; retention in kindergarten at 5 years: RR, 1.3; 95% CI, 1.2–1.4; suspension in kindergarten 5 years: RR, 1.5; 95% CI, 1.2–1.8).
      • Morse S.B.
      • Zheng H.
      • Tang Y.
      • Roth J.
      Early school-age outcomes of late preterm infants.
      Another study (970 late-preterm infants, 13,671 term infants) showed that infants born in the United States at 34-36 weeks' gestation without significant neonatal complications have greater rates of learning difficulties compared with full-term classmates. Late-preterm infants had lower reading scores than full-term infants in kindergarten to first grade. Teacher evaluations of math skills from kindergarten to first grade and reading skills from kindergarten to fifth grade were worse for late-preterm infants. Special education participation was higher for late-preterm infants at early grades.
      • Chyi L.J.
      • Lee H.C.
      • Hintz S.R.
      • Gould J.B.
      • Sutcliffe T.L.
      School outcomes of late preterm infants: special needs and challenges for infants born at 32 to 36 weeks gestation.
      Finally, late-preterm infants (n = 29,631) had a lower likelihood of finishing high school than term infants (n = 601,364) (RR, 0.96; 95% CI, 0.95–0.97; AR, 72% vs 75%).
      • Moster D.
      • Lie R.T.
      • Markestad T.
      Long-term medical and social consequences of preterm birth.
      • Swamy G.K.
      • Ostbye T.
      • Skjaerven R.
      Association of preterm birth with long-term survival, reproduction, and next-generation preterm birth.
      Late-preterm infants (n = 25,193) are also less likely to complete university than term infants (n = 675,340) (OR, 0.87; 95% CI, 0.84–0.89; AR, 32% vs 35%).
      • Moster D.
      • Lie R.T.
      • Markestad T.
      Long-term medical and social consequences of preterm birth.

      Growth

      One study (371 late-preterm infants, 2914 term infants) assessed the effect of late-preterm birth on growth outcomes when infants were 12 and 24 months. This study showed that late-preterm children grew faster than children born at term, but were at increased risk of underweight and stunting in the first 2 years of life. Failure to thrive in the first 2 years may put them at increased risk of future occurrences of serious morbidity in late childhood and of chronic disease development in adult life.
      • Tomashek K.M.
      • Shapiro-Mendoza C.K.
      • Davidoff M.J.
      • Petrini J.R.
      Differences in mortality between late-preterm and term singleton infants in the United States, 1995-2002.

      Young adult social security outcomes

      A Norwegian cohort study (29,711 late-preterm infants, 799,134 term infants) showed that late-preterm infants had a slightly higher risk to receive social security benefits (RR, 1.15; 95% CI, 1.12–1.17).
      • Moster D.
      • Lie R.T.
      • Markestad T.
      Long-term medical and social consequences of preterm birth.

      Comment

      Late-preterm infants are the fastest increasing and largest proportion of singleton preterm births.
      • Davidoff M.J.
      • Dias T.
      • Damus K.
      • et al.
      Changes in the gestational age distribution among US singleton births: impact on rates of late preterm birth, 1992 to 2002.
      • Hibbard J.U.
      • Wilkins I.
      • Sun L.
      • et al.
      Respiratory morbidity in late preterm births.
      Nevertheless, late-preterm infants were less frequently studied compared with extreme preterm infants until recent years. In this study we estimate the magnitude of medical and developmental morbidity due to late-preterm birth. We demonstrate that late-preterm infants have a higher chance for respiratory complications, infections, intraventricular hemorrhage, feeding problems, hypothermia, and hypoglycemia, and they have a higher risk of mortality in the first year of life. Furthermore, late-preterm infants are at increased risk for long-term morbidity such as cerebral palsy and mental retardation. They have also a higher risk for problems during their school career.
      A strength of this review is that both short- and long-term outcomes due to late-preterm birth were assessed and we have attempted to quantify those risks based on a large sample in multiple populations.
      The study also has several limitations. It has been suggested that most of the excess neonatal morbidity in the late-preterm period is related to pregnancy complications (which include preeclampsia, intrauterine growth restrictions, placental abruption) leading to premature delivery rather than to prematurity by itself.
      • Ma X.
      • Huang C.
      • Lou S.
      • et al.
      The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
      • Ananth C.V.
      • Gyamfi C.
      • Jain L.
      Characterizing risk profiles of infants who are delivered at late preterm gestations: does it matter?.
      • Shapiro-Mendoza C.K.
      • Tomashek K.M.
      • Kotelchuck M.
      • et al.
      Effect of late-preterm birth and maternal medical conditions on newborn morbidity risk.
      In this study, we included all infants born late preterm, both late-preterm infants born due to pregnancy complications and prematurity by itself. A subgroup analysis was not possible because of the limited number of eligible studies. Another limitation is that we have not made a selection in late-preterm infants based on, for instance, race, sex, maternal body mass index, mode of delivery, or administration of steroids. This might have resulted in high I2 for some outcomes. Thus, our results reflect the effect of all late-preterm births described in the consulted literature, whatever the cause of preterm birth and other patient or obstetric characteristics. Nevertheless, we think that the heterogeneity in risk profiles of adverse perinatal outcomes by gestational age at delivery provided strong impetus that future research should move away from associating the gestational at delivery, per se, to adverse outcomes, but should focus on the indication(s) for early delivery and the consequences of these indications on short- and long-term infant morbidity.
      • Ananth C.V.
      • Gyamfi C.
      • Jain L.
      Characterizing risk profiles of infants who are delivered at late preterm gestations: does it matter?.
      • Shapiro-Mendoza C.K.
      • Tomashek K.M.
      • Kotelchuck M.
      • et al.
      Effect of late-preterm birth and maternal medical conditions on newborn morbidity risk.
      Our results suggest several areas for future research. More research is needed about the long-term outcomes, such as developmental delay and problems, school performance, and social outcomes due to late-preterm birth. Besides, information is needed about the specific fetal and maternal factors associated with late-preterm birth. We expect that the findings of this study will contribute toward determining the optimal obstetrical management as obstetricians and other clinicians weigh the risks and benefits to mother and child.

      Conclusions

      Late-preterm infants are recognized as the fastest-increasing and largest proportion of singleton preterm births. Although the absolute incidence of neonatal mortality and morbidity on the short and long term is low in infants born late preterm, its incidence is significantly increased as compared to term delivery. This information should be taken into account in the management of women who are at risk for preterm delivery near term.

      References

        • Raju T.N.
        • Higgins R.D.
        • Stark A.R.
        • Leveno K.J.
        Optimizing care and outcome for late-preterm (near-term) infants: a summary of the workshop sponsored by the National Institute of Child Health and Human Development.
        Pediatrics. 2006; 118: 1207-1214
        • Santos I.S.
        • Matijasevich A.
        • Silveira M.F.
        • et al.
        Associated factors and consequences of late preterm births: results from the 2004 Pelotas birth cohort.
        Paediatr Perinat Epidemiol. 2008; 22: 350-359
        • Davidoff M.J.
        • Dias T.
        • Damus K.
        • et al.
        Changes in the gestational age distribution among US singleton births: impact on rates of late preterm birth, 1992 to 2002.
        Semin Perinatol. 2006; 30: 8-15
        • Mateus J.
        • Fox K.
        • Jain S.
        • Jain S.
        • Latta R.
        • Cohen J.
        Preterm premature rupture of membranes: clinical outcomes of late-preterm infants.
        Clin Pediatr (Phila). 2010; 49: 60-65
        • Morse S.B.
        • Zheng H.
        • Tang Y.
        • Roth J.
        Early school-age outcomes of late preterm infants.
        Pediatrics. 2009; 123: e622-e629
        • Kirkegaard I.
        • Obel C.
        • Hedegaard M.
        • Henriksen T.B.
        Gestational age and birth weight in relation to school performance of 10-year-old children: a follow-up study of children born after 32 completed weeks.
        Pediatrics. 2006; 118: 1600-1606
        • Moster D.
        • Lie R.T.
        • Markestad T.
        Long-term medical and social consequences of preterm birth.
        N Engl J Med. 2008; 359 (262–23)
        • Higgins J.P.
        • Thompson S.G.
        Quantifying heterogeneity in a meta-analysis.
        Stat Med. 2002; 21: 1539-1558
        • Burke C.
        • Morrison J.J.
        Perinatal factors and preterm delivery in an Irish obstetric population.
        J Perinat Med. 2000; 28: 49-53
        • Champion V.
        • Durrmeyer X.
        • Dassieu G.
        Short-term respiratory outcome of late preterm newborn in a center of level III [in French].
        Arch Pediatr. 2010; 17: 19-25
        • Cohen-Wolkowiez M.
        • Moran C.
        • Benjamin D.K.
        • et al.
        Early and late onset sepsis in late preterm infants.
        Pediatr Infect Dis J. 2009; 28: 1052-1056
        • Kalia J.L.
        • Visintainer P.
        • Brumberg H.L.
        • Pici M.
        • Kase J.
        Comparison of enrollment in interventional therapies between late-preterm and very preterm infants at 12 months' corrected age.
        Pediatrics. 2009; 123: 804-809
        • Kramer M.S.
        • Demissie K.
        • Yang H.
        • Platt R.W.
        • Sauve R.
        • Liston R.
        The contribution of mild and moderate preterm birth to infant mortality: Fetal and Infant Health Study Group of the Canadian Perinatal Surveillance System.
        JAMA. 2000; 284: 843-849
        • Malloy M.H.
        Impact of cesarean section on intermediate and late preterm births: United States, 2000-2003.
        Birth. 2009; 36: 26-33
        • Vachharajani A.J.
        • Dawson J.G.
        Short-term outcomes of late preterms: an institutional experience.
        Clin Pediatr (Phila). 2009; 48: 383-388
        • Khashu M.
        • Narayanan M.
        • Bhargava S.
        • Osiovich H.
        Perinatal outcomes associated with preterm birth at 33 to 36 weeks' gestation: a population-based cohort study.
        Pediatrics. 2009; 123: 109-113
        • Lindstrom K.
        • Winbladh B.
        • Haglund B.
        • Hjern A.
        Preterm infants as young adults: a Swedish national cohort study.
        Pediatrics. 2007; 120: 70-77
        • Romeo D.M.
        • Di S.A.
        • Conversano M.
        • et al.
        Neurodevelopmental outcome at 12 and 18 months in late preterm infants.
        Eur J Paediatr Neurol. 2010; 14: 503-507
        • Swamy G.K.
        • Ostbye T.
        • Skjaerven R.
        Association of preterm birth with long-term survival, reproduction, and next-generation preterm birth.
        JAMA. 2008; 299: 1429-1436
        • van Baar A.L.
        • Vermaas J.
        • Knots E.
        • de Kleine M.J.
        • Soons P.
        Functioning at school age of moderately preterm children born at 32 to 36 weeks' gestational age.
        Pediatrics. 2009; 124: 251-257
        • Baron I.S.
        • Erickson K.
        • Ahronovich M.D.
        • Coulehan K.
        • Baker R.
        • Litman F.R.
        Visuospatial and verbal fluency relative deficits in 'complicated' late-preterm preschool children.
        Early Hum Dev. 2009; 85: 751-754
        • Bastek J.A.
        • Sammel M.D.
        • Pare E.
        • Srinivas S.K.
        • Posencheg M.A.
        • Elovitz M.A.
        Adverse neonatal outcomes: examining the risks between preterm, late preterm, and term infants.
        Am J Obstet Gynecol. 2008; 199: 367-368
        • Chyi L.J.
        • Lee H.C.
        • Hintz S.R.
        • Gould J.B.
        • Sutcliffe T.L.
        School outcomes of late preterm infants: special needs and challenges for infants born at 32 to 36 weeks gestation.
        J Pediatr. 2008; 153: 25-31
        • Guasch X.D.
        • Torrent F.R.
        • Martinez-Nadal S.
        • Ceren C.V.
        • Saco M.J.
        • Castellvi P.S.
        Late preterm infants: a population at underestimated risk [in Spanish].
        An Pediatr (Barc). 2009; 71: 291-298
        • Gurka M.J.
        • LoCasale-Crouch J.
        • Blackman J.A.
        Long-term cognition, achievement, socioemotional, and behavioral development of healthy late-preterm infants.
        Arch Pediatr Adolesc Med. 2010; 164: 525-532
        • Hibbard J.U.
        • Wilkins I.
        • Sun L.
        • et al.
        Respiratory morbidity in late preterm births.
        JAMA. 2010; 304: 419-425
        • Kalyoncu O.
        • Aygun C.
        • Cetinoglu E.
        • Kucukoduk S.
        Neonatal morbidity and mortality of late-preterm babies.
        J Matern Fetal Neonatal Med. 2010; 23: 607-612
        • Kitsommart R.
        • Janes M.
        • Mahajan V.
        • et al.
        Outcomes of late-preterm infants: a retrospective, single-center, Canadian study.
        Clin Pediatr (Phila). 2009; 48: 844-850
        • Lubow J.M.
        • How H.Y.
        • Habli M.
        • Maxwell R.
        • Sibai B.M.
        Indications for delivery and short-term neonatal outcomes in late preterm as compared with term births.
        Am J Obstet Gynecol. 2009; 200: e30-e33
        • Ma X.
        • Huang C.
        • Lou S.
        • et al.
        The clinical outcomes of late preterm infants: a multi-center survey of Zhejiang, China.
        J Perinat Med. 2009; 37: 695-699
        • McIntire D.D.
        • Leveno K.J.
        Neonatal mortality and morbidity rates in late preterm births compared with births at term.
        Obstet Gynecol. 2008; 111: 35-41
        • Melamed N.
        • Klinger G.
        • Tenenbaum-Gavish K.
        • et al.
        Short-term neonatal outcome in low-risk, spontaneous, singleton, late preterm deliveries.
        Obstet Gynecol. 2009; 114: 253-260
        • Petrini J.R.
        • Dias T.
        • McCormick M.C.
        • Massolo M.L.
        • Green N.S.
        • Escobar G.J.
        Increased risk of adverse neurological development for late preterm infants.
        J Pediatr. 2009; 154: 169-176
        • Pulver L.S.
        • Guest-Warnick G.
        • Stoddard G.J.
        • Byington C.L.
        • Young P.C.
        Weight for gestational age affects the mortality of late preterm infants.
        Pediatrics. 2009; 123: e1072-e1077
        • Santos I.S.
        • Matijasevich A.
        • Domingues M.R.
        • Barros A.J.
        • Victora C.G.
        • Barros F.C.
        Late preterm birth is a risk factor for growth faltering in early childhood: a cohort study.
        BMC Pediatr. 2009; 9: 71
        • Tomashek K.M.
        • Shapiro-Mendoza C.K.
        • Davidoff M.J.
        • Petrini J.R.
        Differences in mortality between late-preterm and term singleton infants in the United States, 1995-2002.
        J Pediatr. 2007; 151: 450-456
        • Wang M.L.
        • Dorer D.J.
        • Fleming M.P.
        • Catlin E.A.
        Clinical outcomes of near-term infants.
        Pediatrics. 2004; 114: 372-376
        • Yoder B.A.
        • Gordon M.C.
        • Barth Jr, W.H.
        Late-preterm birth: does the changing obstetric paradigm alter the epidemiology of respiratory complications?.
        Obstet Gynecol. 2008; 111: 814-822
        • Young P.C.
        • Glasgow T.S.
        • Li X.
        • Guest-Warnick G.
        • Stoddard G.
        Mortality of late-preterm (near-term) newborns in Utah.
        Pediatrics. 2007; 119: e659-e665
        • Ananth C.V.
        • Gyamfi C.
        • Jain L.
        Characterizing risk profiles of infants who are delivered at late preterm gestations: does it matter?.
        Am J Obstet Gynecol. 2008; 199: 329-331
        • Shapiro-Mendoza C.K.
        • Tomashek K.M.
        • Kotelchuck M.
        • et al.
        Effect of late-preterm birth and maternal medical conditions on newborn morbidity risk.
        Pediatrics. 2008; 121: e223-e232