Perinatal Outcome After Fetal Reduction From Twin to Singleton: To Reduce or Not to Reduce?

ABSTRACTTwin pregnancies have higher rates of preterm delivery and neonatal mortality than singleton pregnancies. Elective single embryo transfer (SET) has proved an effective approach to minimize the risk of multiple pregnancies in couples undergoing assisted reproductive technologies, but the risk of multiple pregnancies still remains. While studies show that multifetal pregnancy reduction (MFPR) of triplets and quadruplets to twins results in favorable perinatal outcomes, MFPR of twin pregnancies to singletons has not been widely accepted, and data regarding those outcomes are limited. This study aims to determine perinatal outcomes of MFPR from twin gestation to singleton pregnancy.The retrospective cohort study included a study group of 63 patients who underwent MFPR from dichorionic diamniotic twins to singletons at 11 to 14 weeks’ gestation and a control group of 62 age-matched patients pregnant with dichorionic diamniotic twins who did not undergo MFPR. Both groups received prenatal care at a single tertiary care medical center between January 2005 and December 2012. Patients who underwent MFPR elected to do so because of personal or social reasons or out of concern of prematurity of twin gestations.The study group had a significantly higher gestational age at delivery than did the control group (39 vs 37 weeks, P < 0.01), and birth weight was also higher in the study group (3,076 g vs 2,564 g; P < 0.01). Rates of preterm delivery were significantly lower among patients who underwent MFPR at both less than 34 weeks (1.6% vs 11.7%, P = 0.02) and less than 37 weeks of gestation (9.5% vs 56%; P < 0.001). At less than 32 weeks of gestation, there was a decreased rate of preterm delivery in the group reduced to singletons (1.6% vs 8.3%; P = 0.1), but this was not significant. Rates were comparable among both groups for gestational diabetes (11.1% vs 10%), intrauterine growth restriction (0% vs 3.3%), and hypertensive diseases of pregnancy (6.3% vs 15%), as well as cesarean deliveries (44.4% vs 56.7%). None of the reduced pregnancies experienced pregnancy loss after the MFPR procedure. The 2 groups had similar rates of miscarriage (0% in the reduced group vs 4.8% in the nonreduced group; P = 0.12) and early pregnancy loss before 24 weeks of gestation (0% vs 3.2%; P = 0.24).The findings and comparison with other data showed lower loss rates and more favorable perinatal outcomes for twins reduced to singletons than nonreduced twin pregnancies. While electi