Neonatal outcomes of singleton live births with vanishing twin syndrome following transfer of double embryos in assisted reproductive technology: a retrospective cohort study

Abstract

To compare neonatal outcomes in singleton live births between groups with and without VTs following transfer of double embryos. Retrospective cohort study. Anonymised data on all cycles performed in the China were obtained from the Reproductive medicine department of the Third Affiliated Hospital of Zhengzhou University, involving 6220 singleton live births (2772 fresh embryos transfer (ET) cycles and 3448 frozen embryos transfer (FET) cycles). We analyzed the obstetric outcomes of gestation age, PTB, SGA (small for gestation age), birthweight, LBW, congenital malformation, pediatric admission and NICU admission in cycles of fresh ET and FET. Logistic regression analysis was performed adjusting for confounders, including age of women, BMI, value of AMH, infertile years, current cycle, antral follicles, cause of infertility, number of oocytes retrieved, endometrial thickness at the day of transplantation, number of high-quality embryos, embryo stage. In the fresh ET cycles, the birthweight and gestational age in the study group were lower than in the control group, (2962.4±563.1vs. 3104.9±498.5, p=0.000) and (262.8±8.4vs. 268.9±13.9, p=0.000), respectively. There was a significantly higher risk of PTB (adjusted odds ratio(aOR) 2.45,95%CI:1.98-3.03)) and LBW (aOR 2.11, 95%CI :1.67-2.65) in the study group than in the control group. And there was a higher risk of pediatric admission (aOR 2.55,95%CI2.07-3.13) and NICU admission (aOR 1.98,95%CI1.32-2.96) in the study group than in the control group, and In the FET cycles, the gestational age and birthweight in the study group were lower than in the control group, (263.0±15.7vs. 273.0±10.5, p=0.000) and (3099±662.1vs. 3352±671.5), respectively. There is a significantly higher risk of PTB (aOR2.45,95%CI: 2.23-3.43) and LBW (aOR 2.67, 95%CI :2.13-3.34) in the study group than in the control group. And there was a higher risk of pediatric admission (aOR2.62,95%CI2.14-3.21) and NICU admission (aOR 2.22,95%CI1.43,3.46) in the study group than in the control group. There was a higher risk of LBW, PTB, pediatric admission and NICU admission between the study groups and control groups in fresh ET and FET cycles. However, no increased risk of SGA and congenital malformation was observed in singleton live births in both fresh and frozen ART cycles following transferring double embryos.