Perinatal outcome and timing of selective fetal reduction in dichorionic diamniotic twin pregnancies: a single-center retrospective study

Abstract

ObjectiveThe study aimed to evaluate the pregnancy outcomes of dichorionic diamniotic twin pregnancies that were reduced to singletons at different gestational ages.Study designThis was a retrospective cohort study of twin pregnancies that underwent fetal reduction to singletons in a single tertiary referral center between 2011 and 2020. A total of 433 cases were included. The cohort was divided into five groups according to gestational age at surgery: Group A: <16 weeks (125 cases); Group B: 16–19+6 weeks (80 cases); Group C: 20–23+6 weeks (74 cases); Group D: 24–26+6 weeks (48 cases); and Group E: ≥27 weeks (106 cases). Outcome data were obtained by reviewing the electronic medical records or interviews.ResultsSelective reduction was technically successful. The clinical characteristics of the population were not different. The overall live birth rate and the survival rate were 96.5 and 95.4%, respectively. Although the rate of spontaneous miscarriage was comparable, gestational age at delivery significantly differed among groups (p < 0.001). Additionally, there was a trend that gestational age at delivery decreased with the increasing gestational age at surgery in Groups A, B, C, and D, whereas gestational age at delivery in Group E was later than that in Group D. In Groups A, B, C, and D, the rates of preterm birth at <32 weeks and <34 weeks increased with the increasing gestational age at surgery, while the rates in Group E were significantly lower than that in Group D. Regression analysis showed that timing of reduction may be an independent factor after adjusting for maternal age, parity, pre-pregnancy BMI, ART, and cervical length.ConclusionSelective reduction performed by experienced hands for a dizygotic abnormal twin is safe and effective. Gestational age at surgery (<26+6 weeks) was inversely correlated with gestational age at delivery and positively with the rate of preterm birth. Reduction after 27 weeks, where legal, can be performed with a good outcome for the retained fetus.