Fetal reduction of triplet pregnancies to twins vs singletons: a meta-analysis of survival and pregnancy outcome

Published:March 26, 2022DOI:


      This systematic review and meta-analysis aimed to compare the fetal survival rate and perinatal outcomes of triplet pregnancies after selective reduction to twin pregnancies vs singleton pregnancies.

      Data Sources

      PubMed, Web of Science, Scopus, and Embase were systematically searched from the inception of the databases to January 16, 2022.

      Study Eligibility Criteria

      Studies comparing the survival and perinatal outcomes between reduction to twin pregnancies and reduction to singleton pregnancies were included. The primary outcomes were fetal survival, defined as a live birth at >24 weeks of gestation. The secondary outcomes were gestational age at birth, preterm birth at <32 and <34 weeks of gestation, early pregnancy loss (<24 weeks of gestation), low birthweight, and rate of neonatal demise (up to 28 days after birth).


      The random-effect model was used to pool the mean differences or odds ratios and the corresponding 95% confidence intervals. To provide a range of expected effects if a new study was conducted, 95% prediction intervals were calculated for outcomes presented in >3 studies.


      Of note, 10 studies with 2543 triplet pregnancies undergoing fetal reduction, of which 2035 reduced to twin pregnancies and 508 reduced to singleton pregnancies, met the inclusion criteria. Reduction to twin pregnancies had a lower rate of fetal survival (odds ratio, 0.61; 95% confidence interval, 0.40–0.92; P=.02; 95% prediction interval, 0.36–1.03) and comparable rates of early pregnancy loss (odds ratio, 0.89; 95% confidence interval, 0.58–1.38; P=.61; 95% prediction interval, 0.54–1.48) and neonatal demise (odds ratio, 0.57; 95% confidence interval, 0.09–3.50; P=.55) than reduction to singleton pregnancies. Reduction to twin pregnancies had a significantly lower gestation age at birth (weeks) (mean difference, −2.20; 95% confidence interval, −2.80 to −1.61; P<.001; 95% prediction interval, −4.27 to −0.14) than reduction to singleton pregnancies. Furthermore, reduction to twin pregnancies was associated with lower birthweight and greater risk of preterm birth at <32 and <34 weeks of gestation.


      Triplet pregnancies reduced to twin pregnancies had a lower fetal survival rate of all remaining fetuses, lower gestational age at birth, higher risk of preterm birth, and lower birthweight than triplet pregnancies reduced to singleton pregnancies; reduction to twin pregnancies vs reduction to singleton pregnancies showed no substantial difference for the rates of early pregnancy loss and neonatal death.

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        • Berkowitz R.L.
        • Lynch L.
        • Chitkara U.
        • Wilkins I.A.
        • Mehalek K.E.
        • Alvarez E.
        Selective reduction of multifetal pregnancies in the first trimester.
        N Engl J Med. 1988; 318: 1043-1047
        • Evans M.I.
        • Fletcher J.C.
        • Zador I.E.
        • Newton B.W.
        • Quigg M.H.
        • Struyk C.D.
        Selective first-trimester termination in octuplet and quadruplet pregnancies: clinical and ethical issues.
        Obstet Gynecol. 1988; 71: 289-296
        • Evans M.I.
        • Hanft R.S.
        The introduction of new technologies.
        ACOG Clin Rev. 1997; 2: 1-14
        • Hamilton B.E.
        • Martin J.A.
        • Osterman M.J.
        Births: preliminary data for 2015.
        Natl Vital Stat Rep. 2016; 65: 1-15
        • MacKay A.P.
        • Berg C.J.
        • King J.C.
        • Duran C.
        • Chang J.
        Pregnancy-related mortality among women with multifetal pregnancies.
        Obstet Gynecol. 2006; 107: 563-568
        • Tarter J.G.
        • Khoury A.
        • Barton J.R.
        • Jacques D.L.
        • Sibai B.M.
        Demographic and obstetric factors influencing pregnancy outcome in twin gestations.
        Am J Obstet Gynecol. 2002; 186: 910-912
        • Lemos E.V.
        • Zhang D.
        • Van Voorhis B.J.
        • Hu X.H.
        Healthcare expenses associated with multiple vs singleton pregnancies in the United States.
        Am J Obstet Gynecol. 2013; 209: 586.e1-586.e11
        • Evans M.I.
        • Curtis J.
        • Evans S.M.
        • Britt D.W.
        Fetal reduction and twins.
        Am J Obstet Gynecol MFM. 2022; 4: 100521
        • Pasquini L.
        • Pontello V.
        • Kumar S.
        Intracardiac injection of potassium chloride as method for feticide: experience from a single UK tertiary centre.
        BJOG. 2008; 115: 528-531
        • Coffler M.S.
        • Kol S.
        • Drugan A.
        • Itskovitz-Eldor J.
        Early transvaginal embryo aspiration: a safer method for selective reduction in high order multiple gestations.
        Hum Reprod. 1999; 14: 1875-1878
        • Zipori Y.
        • Haas J.
        • Berger H.
        • Barzilay E.
        Multifetal pregnancy reduction of triplets to twins compared with non-reduced triplets: a meta-analysis.
        Reprod Biomed Online. 2017; 35: 296-304
        • Cai P.
        • Ouyang Y.
        • Gong F.
        • Li X.
        Pregnancy outcomes of dichorionic triamniotic triplet pregnancies after in vitro fertilization-embryo transfer: multifoetal pregnancy reduction versus expectant management.
        BMC Pregnancy Childbirth. 2020; 20: 165
        • Moher D.
        • Shamseer L.
        • Clarke M.
        • et al.
        Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement.
        Syst Rev. 2015; 4: 1
        • Stang A.
        Critical evaluation of the Newcastle-Ottawa scale for the assessment of the quality of nonrandomized studies in meta-analyses.
        Eur J Epidemiol. 2010; 25: 603-605
        • Kuhn-Beck F.
        • Moutel G.
        • Weingertner A.S.
        • et al.
        Fetal reduction of triplet pregnancy: one or two?.
        Prenat Diagn. 2012; 32: 122-126
        • Chaveeva P.
        • Kosinski P.
        • Puglia D.
        • Poon L.C.
        • Nicolaides K.H.
        Trichorionic and dichorionic triplet pregnancies at 10-14 weeks: outcome after embryo reduction compared to expectant management.
        Fetal Diagn Ther. 2013; 34: 199-205
        • Li R.
        • Chen X.
        • Yang S.
        • et al.
        Retain singleton or twins? Multifetal pregnancy reduction strategies in triplet pregnancies with monochorionic twins.
        Eur J Obstet Gynecol Reprod Biol. 2013; 167: 146-148
        • Lin H.
        • Wen Y.
        • Li Y.
        • Chen X.
        • Yang D.
        • Zhang Q.
        Early fetal reduction of dichorionic triplets to dichorionic twin or singleton pregnancies: a retrospective study.
        Reprod Biomed Online. 2016; 32: 490-495
        • Morlando M.
        • Ferrara L.
        • D’Antonio F.
        • et al.
        Dichorionic triplet pregnancies: risk of miscarriage and severe preterm delivery with fetal reduction versus expectant management. Outcomes of a cohort study and systematic review.
        BJOG. 2015; 122: 1053-1060
        • Drugan A.
        • Weissman A.
        Multi-fetal pregnancy reduction (MFPR) to twins or singleton - medical justification and ethical slippery slope.
        J Perinat Med. 2017; 45: 181-184
        • Liu Y.
        • Shen Y.
        • Zhang H.
        • et al.
        Clinical outcomes of multifetal pregnancy reduction in trichorionic and dichorionic triplet pregnancies: a retrospective observational study.
        Taiwan J Obstet Gynecol. 2019; 58: 133-138
        • Zemet R.
        • Haas J.
        • Bart Y.
        • et al.
        Pregnancy outcome after multifetal pregnancy reduction of triplets to twins versus reduction to singletons.
        Reprod Biomed Online. 2020; 40: 445-452
        • Yan L.
        • Wang X.
        • Li H.
        • Hou H.
        • Wang H.
        • Wang Y.
        Effects of the timing of selective reduction and finishing number of fetuses on the perinatal outcome in triplets: a single-center retrospective study.
        J Matern Fetal Neonatal Med. 2020; ([Epub ahead of print])
        • Papageorghiou A.T.
        • Liao A.W.
        • Skentou C.
        • Sebire N.J.
        • Nicolaides K.H.
        Trichorionic triplet pregnancies at 10-14 weeks: outcome after embryo reduction compared to expectant management.
        J Matern Fetal Neonatal Med. 2002; 11: 307-312
        • Antsaklis A.
        • Souka A.P.
        • Daskalakis G.
        • et al.
        Embryo reduction versus expectant management in triplet pregnancies.
        J Matern Fetal Neonatal Med. 2004; 16: 219-222
        • Ata B.
        • Rasillo L.J.
        • Sukhdeo S.
        • Son W.Y.
        • Tan S.L.
        • Dahan M.H.
        Obstetric outcomes of IVF trichorionic triamniotic triplets which are spontaneously or electively reduced to twins.
        J Assist Reprod Genet. 2011; 28: 1217-1222
        • Drugan A.
        • Ulanovsky I.
        • Burke Y.
        • Blazer S.
        • Weissman A.
        Fetal reduction in triplet gestations: twins still fare better.
        Isr Med Assoc J. 2013; 15: 745-747
        • Shiva M.
        • Mohammadi Yeganeh L.
        • Mirzaagha E.
        • Chehrazi M.
        • Bagheri Lankarani N.
        Comparison of the outcomes between reduced and nonreduced triplet pregnancies achieved by assisted reproductive technology.
        Aust N Z J Obstet Gynaecol. 2014; 54: 424-427
        • Haas J.
        • Hourvitz A.
        • Dor J.
        • et al.
        Pregnancy outcome of early multifetal pregnancy reduction: triplets to twins versus triplets to singletons.
        Reprod Biomed Online. 2014; 29: 717-721
        • Okyay E.
        • Altunyurt S.
        • Soysal D.
        • et al.
        A comparative study of obstetric outcomes in electively or spontaneously reduced triplet pregnancies.
        Arch Gynecol Obstet. 2014; 290: 177-184
        • Van De Mheen L.
        • Everwijn S.M.
        • Knapen M.F.
        • et al.
        The effectiveness of multifetal pregnancy reduction in trichorionic triplet gestation.
        Am J Obstet Gynecol. 2014; 211: 536.e1-536.e6
        • Sun L.
        • Zou G.
        • Zhou F.
        • Yang Y.
        • Oepkes D.
        • Duan T.
        Outcome of dichorionic triamniotic triplet: the experience from an emerging fetal therapy center.
        J Matern Fetal Neonatal Med. 2018; 31: 3075-3079
        • Herlihy N.
        • Naqvi M.
        • Romero J.
        • et al.
        Multifetal pregnancy reduction of trichorionic triplet gestations: what is the benefit?.
        Am J Perinatol. 2017; 34: 1417-1423
        • Shaw C.J.
        • Paramasivam G.
        • Vacca C.
        • Lees C.C.
        Expectant management versus multifetal pregnancy reduction in dichorionic triamniotic (DCTA) triplets: single centre experience.
        Eur J Obstet Gynecol Reprod Biol. 2021; 264: 200-205
        • Karamustafaoglu Balci B.
        • Yayla M.
        • Bulut N.
        • Goynumer G.
        Expectant management of triplets or multifetal reduction to twins; comparison of preterm delivery and live birth rates.
        Eur J Obstet Gynecol Reprod Biol. 2022; 268: 18-21
        • Lee J.Y.
        • Lee S.M.
        • Jeong M.
        • et al.
        Short-term and long-term outcomes of trichorionic triplet pregnancies with expectant management.
        Acta Obstet Gynecol Scand. 2022; 101: 111-118
        • Evans M.I.
        • Kaufman M.I.
        • Urban A.J.
        • Britt D.W.
        • Fletcher J.C.
        Fetal reduction from twins to a singleton: a reasonable consideration?.
        Obstet Gynecol. 2004; 104: 102-109
        • Stone J.
        • Ferrara L.
        • Kamrath J.
        • et al.
        Contemporary outcomes with the latest 1000 cases of multifetal pregnancy reduction (MPR).
        Am J Obstet Gynecol. 2008; 199: 406.e1-406.e4
        • Evans M.I.
        • Andriole S.
        • Britt D.W.
        Fetal reduction: 25 years’ experience.
        Fetal Diagn Ther. 2014; 35: 69-82
        • Rosner M.
        • Pergament E.
        • Andriole S.
        • Gebb J.
        • Dar P.
        • Evans M.I.
        Detection of genetic abnormalities by using CVS and FISH prior to fetal reduction in sonographically normal appearing fetuses.
        Prenat Diagn. 2013; 33: 940-944