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When to stop pushing: effects of duration of second-stage expulsion efforts on maternal and neonatal outcomes in nulliparous women with epidural analgesia

  • Camille Le Ray
    Correspondence
    Reprints: Camille Le Ray, MD, MSc, INSERM Unit 953, Epidemiological Research Unit on Perinatal Health and Women's Health, 82 Avenue Denfert-Rochereau, 75014 Paris, France
    Affiliations
    Department of Obstetrics and Gynecology, Sainte Justine Hospital, University of Montréal, Montreal, QC, Canada

    Epidemiological Research Unit on Perinatal Health and Women's Health, INSERM UMR S953, and Maternité Port Royal, Hôpital Cochin Saint-Vincent-de-Paul, Assistance Publique Hôpitaux de Paris, Université Paris-Descartes, Paris, France
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  • François Audibert
    Affiliations
    Department of Obstetrics and Gynecology, Sainte Justine Hospital, University of Montréal, Montreal, QC, Canada
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  • François Goffinet
    Affiliations
    Epidemiological Research Unit on Perinatal Health and Women's Health, INSERM UMR S953, and Maternité Port Royal, Hôpital Cochin Saint-Vincent-de-Paul, Assistance Publique Hôpitaux de Paris, Université Paris-Descartes, Paris, France
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  • William Fraser
    Affiliations
    Department of Obstetrics and Gynecology, Sainte Justine Hospital, University of Montréal, Montreal, QC, Canada
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      Objective

      The purpose of this study was to assess the influence of the duration of active second-stage labor on maternal and neonatal outcomes.

      Study Design

      Secondary analysis of the Pushing Early Or Pushing Late with Epidural trial that included 1862 nulliparous women with epidural analgesia who were in the second stage of labor. According to duration of active second-stage labor, we estimated the proportion of spontaneous vaginal deliveries (SVD) with a newborn infant without signs of asphyxia (5-minute Apgar score ≥7 and arterial pH >7.10). We also analyzed maternal and neonatal outcomes according to the duration of expulsive efforts.

      Results

      Relative to the first hour of expulsive efforts, the chances of a SVD of a newborn infant without signs of asphyxia decreased significantly every hour (1- to 2-hour adjusted odds ratio, 0.4; 95% confidence interval [CI], 0.3–0.6; 2- to 3-hour adjusted odds ratio, 0.1; 95% CI, 0.09–0.2; >3-hour adjusted odds ratio, 0.03; 95% CI, 0.02–0.05). The risk of postpartum hemorrhage and intrapartum fever increased significantly after 2 hours of pushing.

      Conclusion

      Faced with a decreasing probability of SVD and increased maternal risk of morbidity after 2 hours, we raise the question as to whether expulsive efforts should be continued after this time.

      Key words

      The second stage of labor commences at full dilation and is divided into 2 phases: the passive second stage when the fetal head progresses passively in the maternal pelvis and the active second stage that corresponds to the phase of active expulsive efforts. Prolonged second stage of labor (>2 or 3 hours, according to the articles) is associated with an increased risk of maternal complications, operative vaginal delivery, perineal trauma, chorioamnionitis, and postpartum hemorrhage (PPH), but not with an increased risk of adverse neonatal outcomes.
      • Myles T.D.
      • Santolaya J.
      Maternal and neonatal outcomes in patients with a prolonged second stage of labor.
      • Menticoglou S.M.
      • Manning F.
      • Harman C.
      • Morrison I.
      Perinatal outcome in relation to second-stage duration.
      • Cheng Y.W.
      • Hopkins L.M.
      • Caughey A.B.
      How long is too long: does a prolonged second stage of labor in nulliparous women affect maternal and neonatal outcomes?.
      • Janni W.
      • Schiessl B.
      • Peschers U.
      • et al.
      The prognostic impact of a prolonged second stage of labor on maternal and fetal outcome.
      • Moon J.M.
      • Smith C.V.
      • Rayburn W.F.
      Perinatal outcome after a prolonged second stage of labor.
      • Saunders N.S.
      • Paterson C.M.
      • Wadsworth J.
      Neonatal and maternal morbidity in relation to the length of the second stage of labour.
      • Kuo Y.C.
      • Chen C.P.
      • Wang K.G.
      Factors influencing the prolonged second stage and the effects on perinatal and maternal outcomes.
      However, in most studies that are related to a prolonged second stage of labor, passive and active second stages were not differentiated. Because the point of onset of the second stage is difficult to determine, especially when the vaginal examinations during labor are less frequent, a measurement bias in these studies cannot be excluded.
      • Altman M.R.
      • Lydon-Rochelle M.T.
      Prolonged second stage of labor and risk of adverse maternal and perinatal outcomes: a systematic review.
      Conversely, the time of commencing expulsive efforts usually is documented accurately. As regards the management of the second stage of labor, no previous cohort study has analyzed maternal and neonatal outcome indicators specifically as a function of the duration of the active phase of the second stage of labor.
      For Editors' Commentary, see Table of Contents
      See related editorial, page 337
      Several trials have been published about the management of the second stage of labor as regards a policy of immediate or delayed pushing, with controversial results. The Pushing Early Or Pushing Late with Epidural (PEOPLE) trial is 1 such trial.
      • Fraser W.D.
      • Marcoux S.
      • Krauss I.
      • Douglas J.
      • Goulet C.
      • Boulvain M.
      Multicenter, randomized, controlled trial of delayed pushing for nulliparous women in the second stage of labor with continuous epidural analgesia: the PEOPLE (Pushing Early or Pushing Late with Epidural) study group.
      A metaanalysis of these trials found a decreased risk of rotational or mid-pelvic instrumental deliveries in the delayed pushing group but found nonsignificant reductions of instrumental deliveries, cesarean section deliveries, and adverse neonatal outcomes.
      • Roberts C.L.
      • Torvaldsen S.
      • Cameron C.A.
      • Olive E.
      Delayed versus early pushing in women with epidural analgesia: a systematic review and meta-analysis.
      The authors of that metaanalysis concluded that there is a benefit of delayed pushing in hospitals with high rates of rotational or mid-pelvic procedures but that there is no advantage in hospitals with low rates of these procedures. Thus today, there are still considerable variations in the management of the second stage of labor, according to hospital protocols, obstetricians' habits, and experience.
      With respect to the duration of the active phase of the second stage of labor, we hypothesized that, after a certain duration of pushing, maternal and neonatal risks may outweigh the benefits of continued pushing.
      The purpose of our study was to evaluate the rate of spontaneous vaginal delivery with a newborn infant with no signs of asphyxia according to the duration of the active second stage. We also assessed the influence of the duration of active second stage of labor on maternal and neonatal outcomes to try to determine a “maximal” duration of pushing efforts, adjusting for the second-stage management and delayed or immediate pushing.

      Materials and Methods

      We conducted a secondary analysis of all patients (n = 1862) who were included in the PEOPLE trial, which was a multicenter randomized controlled trial that compared early and delayed pushing with epidural analgesia between October 1994 and September 1996 in 12 academic centers (10 in Canada, 1 in the United States, and 1 in Switzerland). Nulliparous women at term (≥37 weeks of gestation) with a singleton vertex fetus were eligible and were assigned randomly at the beginning of the second stage. Exclusion criteria were abnormal fetal heart rate monitoring during the first stage of labor, maternal fever during the first stage of labor, adverse events during the pregnancy (hypertension, hemorrhage, fetal malformation, intrauterine growth retardation), and any condition that necessitated shortening of the second stage of labor.
      • Fraser W.D.
      • Marcoux S.
      • Krauss I.
      • Douglas J.
      • Goulet C.
      • Boulvain M.
      Multicenter, randomized, controlled trial of delayed pushing for nulliparous women in the second stage of labor with continuous epidural analgesia: the PEOPLE (Pushing Early or Pushing Late with Epidural) study group.
      The clinical trial was approved by the Ethics Committee of Laval University.
      The management of the passive phase of the second stage of labor was standardized. In the early pushing group, women were encouraged to commence pushing immediately on random assignment. In the late pushing group, women were advised to avoid voluntary expulsive efforts for 2 hours unless they felt an irresistible urge to push, the fetal head was visualized at the inspection of the perineum, or a medical indication to shorten the second stage of labor developed. However, there was no standardized management with respect to pushing technique. For women without oxytocin during the first stage, if labor had not progressed within 1 hour after random assignment, oxytocin could be commenced. For women with oxytocin during the first stage, it was continued during the second stage of labor, unless there was an indication to stop the infusion. Fetal status was assessed by continuous electronic heart rate monitoring. Continuous-infusion epidural analgesia followed a standardized protocol.
      Data on the duration of the expulsive efforts was collected prospectively and available for all, with the exception of 4 patients. We categorized the duration of the active phase of the second stage of labor into 4 classes: <1 hour, 1-2 hours, 2-3 hours, and >3 hours.
      The primary outcome was defined as a spontaneous vaginal delivery of an infant with no signs of asphyxia (ie, Apgar score at 5 minutes ≥7 and neonatal arterial pH >7.10, when available). Thus, indications of operative deliveries were taken into account. Indeed, with adequate fetal intrapartum surveillance, women with abnormal fetal heart rate monitoring had earlier operative delivery that allowed the birth of an infant with no signs of asphyxia, in comparison with women with a normal fetal heart rate.
      The secondary maternal outcomes were intrapartum fever, third- and fourth- degree perineal tears, and PPH, which was defined as blood losses of >500 mL with vaginal delivery and >1000 mL with cesarean section delivery. The secondary neonatal outcomes were a 5-minute Apgar score of <7, neonatal arterial pH <7.10, any neonatal trauma (cephalhematoma, other hematoma, fracture, and facial or brachial palsy), and admission to neonatal intensive care unit.
      First, we described the maternal and neonatal baseline characteristics and obstetrics practices in our population. Second, according to the duration of the active phase of the second stage of labor, we determined the rate of spontaneous vaginal delivery with a newborn infant with no sign of asphyxia in each randomized group (immediate or delayed pushing groups). Finally, we conducted univariable and multivariable analyses to assess the association between the duration of expulsive efforts and adverse maternal or neonatal outcomes.
      Statistical analysis was performed with Stata software (version 10.0; Stata Corp, College Station, TX). We used the χ2 test to compare proportions and the Fisher exact test when the population size was small (n < 5). To compare continuous variables, we used analysis of variance, and the variances were assessed by the Bartlett's test.
      For multivariable analysis, we used unconditional logistic regression models to adjust for confounding. Adjusted analysis controlled for maternal age (continuous), gestational age (continuous), ethnic origin (categoric), body mass index at admission (continuous), birthweight (continuous), position of the fetal head at full dilation (categoric), group of randomization (binary: early or late pushing group), and mode of delivery (categoric). For analysis of third- and fourth-degree tear, we also adjusted because of episiotomy and its technique (categoric: none, median, or mediolateral episiotomy). Goodness-of-fit was examined with the Hosmer-Lemeshow test.

      Results

      Maternal and neonatal characteristics are summarized in Table 1. Median duration of pushing efforts was 68 minutes (10th percentile, 17 minutes; 90th percentile, 175 minutes) in the delayed pushing group and 110 minutes (10th percentile, 37 minutes; 90th percentile, 228 minutes) in the immediate pushing group. Six hundred thirty-five women (34.2%) pushed <1 hour; 605 women (32.6%) pushed between 1 and 2 hours; 374 women (20.1%) pushed between 2 and 3 hours, and 244 women (13.1%) had an active second stage of labor for >3 hours.
      TABLE 1Description of the population of nulliparous women (n = 1862)
      CharacteristicMeasure
      Group of randomization, n (%)
       Late pushing936 (50.3)
       Early pushing926 (49.7)
      Maternal age, y
      Data are given as mean ± SD;
      28.1 ± 4.9
      Ethnic origin, n (%)
       White1616 (86.9)
       Asian133 (7.1)
       Other110 (5.9)
      Body mass index at admission, kg/m2,
      Data are given as mean ± SD;
      28.6 ± 4.2
      Gestational age, wk
      Data are given as mean ± SD;
      39.8 ± 1.2
      Onset of labor, n (%)
       Spontaneous1288 (69.2)
       Induction574 (30.8)
        Oxytocin292
        Rupture of membranes156
        Prostaglandins275
      Duration of pushing efforts, min
      Data are given as mean ± SD;
      99.8 ± 68.6
       Late pushing group81.8 ± 61.2
       Early pushing group117.9 ± 70.9
      Duration of pushing efforts, n (%)
       <1 h635 (34.2)
       1-2 h605 (32.6)
       2-3 h374 (20.1)
       >3 h244 (13.1)
      Position of the fetal head at full dilation, n (%)
       Anterior1198 (64.3)
       Transverse200 (10.7)
       Posterior210 (11.3)
       Missing254 (13.6)
      Mode of delivery, n (%)
       Spontaneous vaginal delivery1026 (55.1)
       Assisted vaginal delivery
      forceps, vacuum, manual, or instrumental rotation.
      736 (39.5)
       Cesarean100 (5.4)
      Episiotomy in cases of vaginal delivery, n (%)
      n = 1762;
       None1095 (58.8%)
       Median459 (27.7%)
       Mediolateral308 (16.5%)
      Birthweight, g3469 ± 421
      Le Ray. Expulsion efforts in nulliparous women with epidural analgesia. Am J Obstet Gynecol 2009.
      a Data are given as mean ± SD;
      b n = 1762;
      c forceps, vacuum, manual, or instrumental rotation.
      The 5-minute Apgar score was available in 1857 cases (99.7%), but neonatal arterial pH was missing in 376 observations (20.2%). As shown on the Figure, after the first hour of expulsive efforts, the probability of spontaneous delivery of a baby who has no indicators of asphyxia decreased with time of pushing. Among women who were undelivered after 2 hours of active pushing, the chances of a spontaneous vaginal delivery of an infant with no signs of asphyxia were 22.7% and 19.6% in the immediate and delayed pushing groups, respectively. After 3 hours, the chances decreased to 10.7% and 8.9%. Using multivariable analysis, we found a significantly decreased chance for each subsequent hour to have a spontaneous vaginal delivery with an infant with no signs of asphyxia (interval 1-2 hours: adjusted odds ratio [OR], 0.4; 95% confidence interval [CI], 0.3–0.6; interval 2-3 hours: adjusted OR, 0.1; 95% CI, 0.09–0.2; pushing >3 hours: adjusted OR, 0.03; 95% CI, 0.02–0.1; reference: pushing <1 hour; Table 2).
      Figure thumbnail gr1
      FIGUREProbability of spontaneous vaginal delivery and birth of an infant without sign of asphyxia (pH >7.10 and 5-minute Apgar score ≥7)
      Probability statistics were compiled according to pushing duration and the randomization group among women who were undelivered at the beginning of the period. The closed bars represent delayed pushing; the open bars represent immediate pushing.
      Le Ray. Expulsion efforts in nulliparous women with epidural analgesia. Am J Obstet Gynecol 2009.
      TABLE 2Maternal and neonatal outcomes according to pushing duration: univariable and multivariable analysis, with the use of logistic regression models
      Outcome1–2 h2–3 h>3 h
      Crude odds ratio (95% CI)Adjusted odds ratio (95% CI)
      Adjustment: maternal age, gestational age, ethnic origin, body mass index at the admission, birthweight, position of the fetal head at full dilation, group of randomization (early or late pushing), mode of delivery (except for the primary outcome and operative delivery);
      Crude odds ratio (95% CI)Adjusted odds ratio (95% CI)
      Adjustment: maternal age, gestational age, ethnic origin, body mass index at the admission, birthweight, position of the fetal head at full dilation, group of randomization (early or late pushing), mode of delivery (except for the primary outcome and operative delivery);
      Crude odds ratio (95% CI)Adjusted odds ratio (95% CI)
      Adjustment: maternal age, gestational age, ethnic origin, body mass index at the admission, birthweight, position of the fetal head at full dilation, group of randomization (early or late pushing), mode of delivery (except for the primary outcome and operative delivery);
      Primary outcome: spontaneous vaginal delivery of an infant without a sign of asphyxia0.4 (0.3–0.6)0.4 (0.3–0.6)0.1 (0.09–0.2)0.1 (0.09–0.2)0.03 (0.02–0.05)0.03 (0.02–0.05)
      Operative delivery2.3 (1.8–3.0)2.3 (1.7–3.0)9.3 (6.9–12.5)9.0 (6.5–12.3)32.9 (21.0–51.6)31.0 (19.3–50.0)
      Postpartum hemorrhage1.6 (1.1–2.3)1.2 (0.8–1.8)2.6 (1.8–3.9)1.6 (1.0–2.5)4.9 (3.3–7.4)2.5 (1.5–4.1)
      Third- and 4th-degree perineal tear
      adjustment also on episiotomy and its technique (median or mediolateral).
      1.3 (0.8–2.1)1.0 (0.6–1.6)2.5 (1.6–3.9)1.2 (0.7–2.0)2.9 (1.8–4.7)1.7 (0.9–3.0)
      Intrapartum fever2.0 (1.1–3.4)1.8 (1.0–3.2)2.8 (1.6–5.0)2.1 (1.1–4.0)4.1 (2.3–7.3)2.7 (1.3–5.5)
      5-minute Apgar score <71.7 (0.5–5.2)1.1 (0.3–3.6)1.0 (0.2–4.3)0.4 (0.1–2.1)2.1 (0.6–7.9)0.7 (0.1–3.5)
      Arterial pH ≤7.101.5 (0.8–2.7)1.6 (0.8–3.0)0.5 (0.2–1.2)0.4 (0.1–1.3)0.4 (0.1–1.3)0.2 (0.1–1.1)
      Neonatal trauma1.3 (0.8–2.1)1.2 (0.7–2.0)2.2 (1.4–3.6)1.5 (0.8–2.6)2.5 (1.5–4.1)1.7 (0.9–3.3)
      Admission in neonatal intensive care unit1.2 (0.7–2.2)1.1 (0.6–2.0)2.1 (1.2–3.7)1.5 (0.8–3.0)2.6 (1.5–4.9)1.5 (0.7–3.3)
      Reference: pushing duration <1 hour.
      CI, confidence interval.
      Le Ray. Expulsion efforts in nulliparous women with epidural analgesia. Am J Obstet Gynecol 2009.
      a Adjustment: maternal age, gestational age, ethnic origin, body mass index at the admission, birthweight, position of the fetal head at full dilation, group of randomization (early or late pushing), mode of delivery (except for the primary outcome and operative delivery);
      b adjustment also on episiotomy and its technique (median or mediolateral).
      Univariable analysis indicated that the proportion of maternal morbidity indicators increased significantly with the duration of the active second stage of labor (Table 3). Among women who were undelivered after 2 hours of active pushing, the rate of PPH was 23.6%, which increased to 30.5% after 3 hours of pushing. The risk of operative delivery (instrumental extraction or cesarean section) was increased 2-fold for the 1- to 2-hour interval in comparison with the duration of pushing for <1 hour, 9-fold increased for the 2- to 3-hour interval, and 30-fold increased for pushing >3 hours. After adjustment, the risk of PPH increased after 2 hours of pushing (interval 2-3 hours: adjusted OR, 1.6; 95% CI, 1.0–2.5; pushing >3 hours: adjusted OR, 2.5; 95% CI, 1.5–4.1; reference: pushing <1 hour). The risk of intrapartum fever was also associated significantly with the duration of the active second stage of labor. In the multivariable analysis, the risks of third- and fourth-degree tears were comparable for all classes of the duration of the active second stage (Table 2).
      TABLE 3Maternal and neonatal morbidity indicators according to each pushing duration category
      Indicator<1 h (n = 635)1–2 h (n = 605)2–3 h (n = 374)>3 h (n = 244)P value
      χ2 test with 3 degrees of freedom.
      Postpartum hemorrhage, n (%)53 (8.4)75 (12.7)70 (19.5)64 (31.1)< .001
      Third- to 4th-degree perineal tear, n (%)98 (6.0)47 (7.8)52 (13.9)38 (15.7)< .001
      Intrapartum fever, n (%)21 (3.3)38 (6.3)33 (8.8)30 (12.3)< .001
      Arterial pH (mean ± SD)7.25 ± 0.077.24 ± 0.0877.25 ± 0.077.26 ± 0.07.009
      Arterial pH ≤7.10, n (%)18 (3.6)25 (5.2)5 (1.7)3 (1.4).020
      5 min Apgar score <7, n (n%)5 (0.8)8 (1.3)3 (0.8)4 (1.6).566
      Neonatal trauma, n (%)34 (5.4)41 (6.8)42 (11.2)30 (12.3)< .001
      Admission in neonatal intensive care unit, n (%)22 (3.5)25 (4.1)26 (7.0)21 (8.6).004
      Le Ray. Expulsion efforts in nulliparous women with epidural analgesia. Am J Obstet Gynecol 2009.
      a χ2 test with 3 degrees of freedom.
      In this context of continuous intrapartum surveillance, neonatal arterial pH and 5-minute Apgar score were not influenced by pushing duration (Table 3). Neonatal trauma and admission in the neonatal intensive care unit increased with the duration of the active second stage of labor in univariable analysis. After adjustment for confounding variables, none of the adverse neonatal outcomes that were studied were associated significantly with pushing duration (Table 2).

      Comment

      During the active phase of the second stage of labor, the probability of spontaneous vaginal delivery of an infant with a 5-minute Apgar score ≥7 and pH at birth >7.10, decreases every hour. After 2 hours of pushing, the risk of intrapartum fever and PPH increases significantly. However, our results suggest that, in the context of continuous fetal surveillance in the second stage of labor, a prolonged duration of the active second stage does not increase the risk of adverse neonatal outcome.
      There are few previous publications that specifically have addressed the impact of the duration of expulsive efforts on the fetal and neonatal well-being.
      • Wood C.
      • Ng K.H.
      • Hounslow D.
      • Benning H.
      Time: an important variable in normal delivery.
      • Katz M.
      • Lunenfeld E.
      • Meizner I.
      • Bashan N.
      • Gross J.
      The effect of the duration of the second stage of labour on the acid-base state of the fetus.
      • Nordstrom L.
      • Achanna S.
      • Naka K.
      • Arulkumaran S.
      Fetal and maternal lactate increase during active second stage of labour.
      • Aldrich C.J.
      • D'Antona D.
      • Spencer J.A.
      • et al.
      The effect of maternal pushing on fetal cerebral oxygenation and blood volume during the second stage of labour.
      These studies had a small sample size and were focused on biologic outcomes (pH and lactates). In our study, the population is large and homogenous (nulliparous women with uncomplicated pregnancies at term with epidural analgesia) and is derived from a multicenter trial cohort. The collection of data was prospective and rigorous, especially with respect to the hours of pushing, with missing data for only 4 subjects. We classified pushing duration into 4 classes and demonstrated an increased risk for intrapartum fever and PPH. In previous studies on this topic, some authors have oversimplified categorization of the second stage (<2 and >2 hours), which limits interpretation of their results.
      • Myles T.D.
      • Santolaya J.
      Maternal and neonatal outcomes in patients with a prolonged second stage of labor.
      • Janni W.
      • Schiessl B.
      • Peschers U.
      • et al.
      The prognostic impact of a prolonged second stage of labor on maternal and fetal outcome.
      • Moon J.M.
      • Smith C.V.
      • Rayburn W.F.
      Perinatal outcome after a prolonged second stage of labor.
      • Kuo Y.C.
      • Chen C.P.
      • Wang K.G.
      Factors influencing the prolonged second stage and the effects on perinatal and maternal outcomes.
      Neonatal outcomes were also collected prospectively to analyze accurately the neonatal health status. This reinforces the validity of our results.
      Previous studies concerning prolonged second stage of labor did not differentiate passive and active phases; thus, we cannot compare our results to those from other studies.
      • Myles T.D.
      • Santolaya J.
      Maternal and neonatal outcomes in patients with a prolonged second stage of labor.
      • Menticoglou S.M.
      • Manning F.
      • Harman C.
      • Morrison I.
      Perinatal outcome in relation to second-stage duration.
      • Cheng Y.W.
      • Hopkins L.M.
      • Caughey A.B.
      How long is too long: does a prolonged second stage of labor in nulliparous women affect maternal and neonatal outcomes?.
      • Janni W.
      • Schiessl B.
      • Peschers U.
      • et al.
      The prognostic impact of a prolonged second stage of labor on maternal and fetal outcome.
      • Moon J.M.
      • Smith C.V.
      • Rayburn W.F.
      Perinatal outcome after a prolonged second stage of labor.
      • Saunders N.S.
      • Paterson C.M.
      • Wadsworth J.
      Neonatal and maternal morbidity in relation to the length of the second stage of labour.
      • Kuo Y.C.
      • Chen C.P.
      • Wang K.G.
      Factors influencing the prolonged second stage and the effects on perinatal and maternal outcomes.
      However, in accordance with these studies, after adjustment of data, we did not find an association between duration of pushing and adverse neonatal outcomes.
      In 1973, Wood et al
      • Wood C.
      • Ng K.H.
      • Hounslow D.
      • Benning H.
      Time: an important variable in normal delivery.
      showed, among 29 patients, that neonatal arterial pH decreased to 0.003 units for every minute of pushing. Other authors found similar results in small biologic studies.
      • Katz M.
      • Lunenfeld E.
      • Meizner I.
      • Bashan N.
      • Gross J.
      The effect of the duration of the second stage of labour on the acid-base state of the fetus.
      • Aldrich C.J.
      • D'Antona D.
      • Spencer J.A.
      • et al.
      The effect of maternal pushing on fetal cerebral oxygenation and blood volume during the second stage of labour.
      In our study with a large sample size, in which there was routine fetal intrapartum surveillance with fetal heart monitoring, we found no correlation between neonatal arterial pH values and the duration of expulsive efforts. Moreover, we found a surprising, but not significant, decrease in the rate of arterial pH <7.10 after 2 hours of pushing. This result may reflect a “healthy worker” effect (ie, that the most fragile infants were probably born during the first 2 hours of pushing, if needed, by instrumental vaginal delivery or by cesarean delivery). But this result may also reflect a context of careful obstetric management and an adequate fetal surveillance during the active second stage of labor, by the performance of an operative delivery when severe fetal heart rate abnormalities occurred. Only women with normal fetal heart monitoring were allowed to continue pushing after 2 hours.
      Because this was a secondary analysis of a randomized trial that was not designed specifically to answer the study question, our study had several limitations. We had only short-term data concerning maternal morbidity indicators. The effect of prolonged expulsive efforts on pelvic floor and continence was not assessed. Moreover, data were collected from 1994-1996. Probably, obstetric practices have changed since this period; there might be fewer midpelvic extractions, fewer rotational procedures, and more caesarean deliveries during the second stage. The operative vaginal delivery rate was high in this trial, like in other trials that compared delayed and immediate pushing.
      • Roberts C.L.
      • Torvaldsen S.
      • Cameron C.A.
      • Olive E.
      Delayed versus early pushing in women with epidural analgesia: a systematic review and meta-analysis.
      Thus, a selection bias cannot be excluded. In our population, most women were white or Asian. In light of the different prevalence of pelvic configurations in different ethnic groups, our results might not be generalized to ethnic groups that were under represented in our study. Moreover, our results cannot be generalized to multiparous and nulliparous women who did not have epidural analgesia. Finally, because the exact duration of the first stage of labor is difficult to estimate accurately, we did not adjust for it. First-stage duration might have an influence on maternal and neonatal outcomes.
      Sung et al
      • Sung J.F.
      • Daniels K.I.
      • Brodzinsky L.
      • El-Sayed Y.Y.
      • Caughey A.B.
      • Lyell D.J.
      Cesarean delivery outcomes after a prolonged second stage of labor.
      found that a second stage of labor of >4 hours was associated with an increase in unintentional hysterotomy extensions at cesarean delivery and prolonged operative time. In the PEOPLE trial, there were no data about adverse events that occurred during cesarean delivery (such as hysterotomy extension or bladder injury). These complications may be more frequent in the case of cesarean delivery after 2 or 3 hours of pushing efforts, compared with cesarean deliveries performed during the first 2 hours of active second stage of labor.
      In 1989, Fusi et al
      • Fusi L.
      • Steer P.J.
      • Maresh M.J.
      • Beard R.W.
      Maternal pyrexia associated with the use of epidural analgesia in labour.
      were the first to describe an association between maternal pyrexia and the use of epidural analgesia in labor. Other authors found similar results.
      • Yancey M.K.
      • Zhang J.
      • Schwarz J.
      • Dietrich C.S.3rd
      • Klebanoff M.
      Labor epidural analgesia and intrapartum maternal hyperthermia.
      However, the exact influence of epidural analgesia on thermoregulation is still controversial.
      • Goetzl L.
      • Rivers J.
      • Zighelboim I.
      • Wali A.
      • Badell M.
      • Suresh M.S.
      Intrapartum epidural analgesia and maternal temperature regulation.
      In our population of nulliparous women with epidural analgesia, there was a significantly increased risk of maternal intrapartum fever that was associated with pushing duration. We cannot determine whether this result is due to patent infection or unbalanced thermoregulation.
      Analysis of risk factors that were associated with a prolonged active second stage of labor could lead to the identification of measures to decrease the duration of expulsive efforts and the associated maternal morbidity. In particular, fetal malposition at full dilation results in a higher risk of prolonged second-stage labor.
      • Senecal J.
      • Xiong X.
      • Fraser W.D.
      Effect of fetal position on second-stage duration and labor outcome.
      In contrast to other risk factors such as fetal weight, fetal malposition can be modified with simple obstetric maneuvers. The routine assessment of fetal head position at full dilation before pushing is initiated, and the use of manual rotation might reduce the duration of pushing and the rate of cesarean deliveries.
      • Shaffer B.L.
      • Cheng Y.W.
      • Vargas J.E.
      • Laros Jr, R.K.
      • Caughey A.B.
      Manual rotation of the fetal occiput: predictors of success and delivery.
      • Le Ray C.
      • Serres P.
      • Schmitz T.
      • Cabrol D.
      • Goffinet F.
      Manual rotation in occiput posterior or transverse positions: risk factors and consequences on the cesarean delivery rate.
      • Reichman O.
      • Gdansky E.
      • Latinsky B.
      • Labi S.
      • Samueloff A.
      Digital rotation from occipito-posterior to occipito-anterior decreases the need for cesarean section.
      In our logistic regression analysis, we assessed whether the association between the risk of PPH and the duration of pushing was mediated potentially by the mode of delivery. Cesarean delivery is associated with both duration of pushing and risk of PPH. The adjusted OR for PPH was significantly less than the crude OR, and the confidence interval for the effect excluded the null effect only when the duration of pushing was >3 hours. It remains possible that prolonged pushing is associated with technically difficult cesarean deliveries, in which the risk of hysterotomy extension is increased. Thus, cesarean delivery would be on the chain of causality between pushing duration and PPH.
      PPH is well known to be a common cause of maternal death and morbidity. Considering that the risk of PPH increases significantly after 2 hours of expulsive efforts and the chance to have a spontaneous vaginal delivery of an infant with mo signs of asphyxia is 20% after this time, in our study, it is justified to ask the question as to whether operative delivery (instrumental delivery or cesarean delivery) should be considered after 2 hours of pushing. However, our study did not allow us to assess whether maternal morbidity would have been reduced if an operative delivery had been performed systematically after 2 hours of pushing. A policy of assisted delivery or cesarean delivery after 2 hours of pushing could decrease the risk of PPH that is associated with uterine atony and difficult cesarean deliveries. However, such a policy could also increase the risk of PPH because of an increased rate of cesarean and instrumental delivery. Our study does not provide a definitive answer to that question, but it does provide additional information to assist a physician in a patient's counseling in such situations. Our study revives the age- old debate as to the appropriate criteria for defining an “adequate” or, for that matter, a “failed” trial of labor, which is the ultimate diagnostic conundrum in obstetrics. This unresolved challenge applies both to the first and the second stage of labor. Only a well-designed randomized controlled trial that would compare neonatal and maternal outcomes between (1), a policy of limiting pushing to 2 hours and (2), a policy of no fixed limit on the duration of the active second stage will answer the question of when to stop pushing.

      Acknowledgment

      Participants in the Pushing Early Or Pushing Late with Epidural study group: steering committee: William D. Fraser, MD, Sylvie Marcoux, MD, PhD, Isabelle Krauss, MD, MSc, Joanne Douglas, MD, and Céline Goulet RN, PhD; center investigators and research assistants: J. Chabot, MD, J. Flamand, RN, L. Laperrière, BN, CHUQ–Pavillon St François d'Assise, Quebec, Quebec, Canada; P. Fish, MD, and G. Hamel, RN, Hôpital de Chicoutimi, Chicoutimi, Quebec, Canada; R. Sabbah, MD, and L. Vincelli, RN, Hôpital Sacré-Coeur de Montréal, Montreal, Quebec, Canada; G. Tawagi, MD, O. Rosag, MD, and J. Belcher, RN, Ottawa Civic Hospital, Ottawa, Ontario, Canada; F. Galerneau, MD, M. Klein, MD, J. Swenerton, MD, B. Weibe, RN, and E. Nickel, RN, BC Women's Hospital, Vancouver, British Columbia, Canada; K. Milne, MD, J. Fuller, MD, and L. Watson, RN, St Joseph's Hospital, London, Ontario, Canada; O. Irion, MD, K. Rifat, MD, and V. Mentha (midwife), Hôpitaux Universitaires de Genève, Geneva, Switzerland; S. Bottoms, MD (deceased), and B. Steffy, RN, Hutzel Hospital, Detroit, Michigan; M. Helewa, MD, S. Lucy, MD, and S. Erickson, RN, St Boniface Hospital, Winnipeg, Manitoba, Canada; N. Okun, MD, A. Guest, MD, A. Stuart, MD, and D. Schimeck, RN, University of Alberta Hospital, Edmonton, Alberta, Canada; M. Sermer, MD, and M. Bailey, RN, Toronto General Hospital, Toronto, Ontario, Canada; D. Blouin, MD, Y. Claprood, and D. Beaulieu, RN, Center Hospitalier Universitaire de l'Estrie, Sherbrooke, Quebec, Canada; data management committee: Michel Boulvain, MD, PhD, Sylvie Bérubé, PhD, and Isabelle Faron; safety and efficacy monitoring committee: François Meyer, MD, PhD, Aida Bairam, MD, PhD, and Jean-Marie Moutquin, MD.

      References

        • Myles T.D.
        • Santolaya J.
        Maternal and neonatal outcomes in patients with a prolonged second stage of labor.
        Obstet Gynecol. 2003; 102: 52-58
        • Menticoglou S.M.
        • Manning F.
        • Harman C.
        • Morrison I.
        Perinatal outcome in relation to second-stage duration.
        Am J Obstet Gynecol. 1995; 173: 906-912
        • Cheng Y.W.
        • Hopkins L.M.
        • Caughey A.B.
        How long is too long: does a prolonged second stage of labor in nulliparous women affect maternal and neonatal outcomes?.
        Am J Obstet Gynecol. 2004; 191: 933-938
        • Janni W.
        • Schiessl B.
        • Peschers U.
        • et al.
        The prognostic impact of a prolonged second stage of labor on maternal and fetal outcome.
        Acta Obstet Gynecol Scand. 2002; 81: 214-221
        • Moon J.M.
        • Smith C.V.
        • Rayburn W.F.
        Perinatal outcome after a prolonged second stage of labor.
        J Reprod Med. 1990; 35: 229-231
        • Saunders N.S.
        • Paterson C.M.
        • Wadsworth J.
        Neonatal and maternal morbidity in relation to the length of the second stage of labour.
        BJOG. 1992; 99: 381-385
        • Kuo Y.C.
        • Chen C.P.
        • Wang K.G.
        Factors influencing the prolonged second stage and the effects on perinatal and maternal outcomes.
        J Obstet Gynaecol Res. 1996; 22: 253-257
        • Altman M.R.
        • Lydon-Rochelle M.T.
        Prolonged second stage of labor and risk of adverse maternal and perinatal outcomes: a systematic review.
        Birth. 2006; 33: 315-322
        • Fraser W.D.
        • Marcoux S.
        • Krauss I.
        • Douglas J.
        • Goulet C.
        • Boulvain M.
        Multicenter, randomized, controlled trial of delayed pushing for nulliparous women in the second stage of labor with continuous epidural analgesia: the PEOPLE (Pushing Early or Pushing Late with Epidural) study group.
        Am J Obstet Gynecol. 2000; 182: 1165-1172
        • Roberts C.L.
        • Torvaldsen S.
        • Cameron C.A.
        • Olive E.
        Delayed versus early pushing in women with epidural analgesia: a systematic review and meta-analysis.
        BJOG. 2004; 111: 1333-1340
        • Wood C.
        • Ng K.H.
        • Hounslow D.
        • Benning H.
        Time: an important variable in normal delivery.
        J Obstet Gynaecol Br Commonw. 1973; 80: 295-300
        • Katz M.
        • Lunenfeld E.
        • Meizner I.
        • Bashan N.
        • Gross J.
        The effect of the duration of the second stage of labour on the acid-base state of the fetus.
        BJOG. 1987; 94: 425-430
        • Nordstrom L.
        • Achanna S.
        • Naka K.
        • Arulkumaran S.
        Fetal and maternal lactate increase during active second stage of labour.
        BJOG. 2001; 108: 263-268
        • Aldrich C.J.
        • D'Antona D.
        • Spencer J.A.
        • et al.
        The effect of maternal pushing on fetal cerebral oxygenation and blood volume during the second stage of labour.
        BJOG. 1995; 102: 448-453
        • Sung J.F.
        • Daniels K.I.
        • Brodzinsky L.
        • El-Sayed Y.Y.
        • Caughey A.B.
        • Lyell D.J.
        Cesarean delivery outcomes after a prolonged second stage of labor.
        Am J Obstet Gynecol. 2007; 197: 306.e1-306.e5
        • Fusi L.
        • Steer P.J.
        • Maresh M.J.
        • Beard R.W.
        Maternal pyrexia associated with the use of epidural analgesia in labour.
        Lancet. 1989; 1: 1250-1252
        • Yancey M.K.
        • Zhang J.
        • Schwarz J.
        • Dietrich C.S.3rd
        • Klebanoff M.
        Labor epidural analgesia and intrapartum maternal hyperthermia.
        Obstet Gynecol. 2001; 98: 763-770
        • Goetzl L.
        • Rivers J.
        • Zighelboim I.
        • Wali A.
        • Badell M.
        • Suresh M.S.
        Intrapartum epidural analgesia and maternal temperature regulation.
        Obstet Gynecol. 2007; 109: 687-690
        • Senecal J.
        • Xiong X.
        • Fraser W.D.
        Effect of fetal position on second-stage duration and labor outcome.
        Obstet Gynecol. 2005; 105: 763-772
        • Shaffer B.L.
        • Cheng Y.W.
        • Vargas J.E.
        • Laros Jr, R.K.
        • Caughey A.B.
        Manual rotation of the fetal occiput: predictors of success and delivery.
        Am J Obstet Gynecol. 2006; 194: e7-e9
        • Le Ray C.
        • Serres P.
        • Schmitz T.
        • Cabrol D.
        • Goffinet F.
        Manual rotation in occiput posterior or transverse positions: risk factors and consequences on the cesarean delivery rate.
        Obstet Gynecol. 2007; 110: 873-879
        • Reichman O.
        • Gdansky E.
        • Latinsky B.
        • Labi S.
        • Samueloff A.
        Digital rotation from occipito-posterior to occipito-anterior decreases the need for cesarean section.
        Eur J Obstet Gynecol Reprod Biol. 2008; 136: 25-28

      Linked Article

      • Is there an upper time limit for the management of the second stage of labor?
        American Journal of Obstetrics & GynecologyVol. 201Issue 4
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          The epidemiology of the length of labor was notoriously reported by Emmanuel Friedman1,2 in several landmark articles >50 years ago. These studies changed modern obstetrics; most specifically, they led to specific normative guidelines on the length of the first and second stages of labor. These normative guidelines generally have become prescriptive and have led to operative deliveries if the length of labor crosses some specific time threshold. However, more recently, a variety of authors have challenged this paradigm for both the first and second stages of labor.
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