Clinical outcomes of vanishing twin syndrome and selective fetal reduction after double embryos transferred in IVF pregnancy: A propensity score matching study

Abstract

ObjectiveThe purpose of this study was to analyze the influence of early vanishing twin syndrome (VTS) and selective fetal reduction (SEFR) on surviving singleton births in in-vitro fertilization (IVF) pregnancy. MethodsWe collected patients who conceived through IVF and delivered singletons over the past six years. The VT group (n = 194) and SEFR group (n = 144) had underwent double embryos transferred (DET) and only one fetus was born, due to the subsequent one birth reduction. The SET group had one embryo transferred (SET) and gave birth to singleton. Using the propensity score matching (PSM) method to reduce confounding, the VT group and SEFR group were matched and compared with 570 and 576 singleton controls, respectively (SET-I/II group). Obstetric complications and neonatal outcomes were compared. In addition, quantity and quality of transferred embryos of VT (n = 194) and singleton groups (born with singleton after DET and matched with VT group by PSM, n = 554) were compared. ResultsCompared with the SET-I group, VT group had increased incidence of severe obstetric complications, including severe preeclampsia (p = 0.031), oligohydramnios (p = 0.038) and polyhydramnios (p = 0.015). VT group was more likely to show more frequent small for gestational age (SGA) (p = 0.046) and very small for gestational age (VSGA) (p = 0.031). Newborns in the SEFR group had a significantly lower birth weight (p = 0.005) and were more likely to manifest as low birthweight (LBW) (p = 0.009) and very low birthweight (VLBW, birth weight < 1500 g) (p = 0.012), and the incidence of very large for gestational age (VLGA) was lower (p = 0.030), compared with the control group. There were more developmental abnormalities in newborns of VTS, for decreased incidence of SGA (OR 0.156, 95% CI 0.036–0.669), VSGA (OR 0.057, 95% CI 0.006–0.553) and VLGA (OR 0.415, 95% CI 0.212–0.815) in SEFR group. The good quality embryo rate was higher in VT group (72.7% vs. 63.3%, p = 0.001) compared with the singleton group. ConclusionsDET with subsequent VTS/SEFR carried a higher rate of adverse clinical outcomes, and the VTS group had worse perinatal outcome compared with SEFR. Therefore, we recommend SET in ART.