Risks of Miscarriage or Preterm Delivery in Dichorionic Triamniotic Triplets with Multifetal Embryo Reduction to Singleton Pregnancy Versus Expectant Management: A Systematic Review

Background/Objectives: Dichorionic triamniotic (DCTA) triplet pregnancies are associated with increased rates of placenta-specific complications primarily attributed to vascular anastomoses in the monochorionic (MC) pair. Selective fetal reduction to twins (of one of the MC pair) is a complex and not a widely available procedure. Multifetal reduction (MFR) to singleton pregnancy can reduce adverse pregnancy outcomes but is controversial due to medico-legal and socio-ethical issues. The aim of this study is to identify the rate of miscarriage < 24 weeks or preterm birth < 34 weeks following MFR to singleton pregnancy in DCTA triplets and compare the results with expectant management. Methods: This systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and registered in the Prospective Register of Systematic Reviews System (ID: CRD42023422585). Results: Overall, from 21 citations of relevance, 6 studies with a total of 548 DCTA triplet pregnancies fulfilled the inclusion/exclusion criteria. In comparison with expectant management (n = 336), meta-analysis demonstrated that MFR to singleton pregnancy (n = 212) was associated with a lower rate (9.4% vs. 48.5%) of preterm birth (RR = 0.19, 95%CI 0.07–0.51), whereas the rate of miscarriage (14.6% vs. 9.2%) did not significantly increase (RR = 1.53, 95%CI 0.91–2.55). Conclusions: In DCTA triplet pregnancies, MFR to singleton pregnancy was associated with a reduced preterm birth rate and not associated with an increased miscarriage rate. Given the fact that the MC pair is reduced only to lower the rate of preterm birth, appropriate counselling and justification are important. In the absence of randomized controlled trials, data from systematic reviews are the best available evidence for counseling on the different management options.