Impact of surgical versus spontaneous fetal reduction on maternal and neonatal outcomes after assisted reproductive technology: a single-center cohort study of 1, 451 singleton live births

Objective To compare maternal and neonatal outcomes among pregnancies with surgical reduction, spontaneous reduction, and initial singleton pregnancies following assisted reproductive technology (ART), and to identify independent risk factors for adverse obstetric outcomes. Methods This retrospective cohort study included 1,451 singleton live births after ART at a single center from January 2018 to December 2023. Participants were divided into three groups: surgical reduction (n=128), spontaneous reduction (n=156), and initial singleton control group (n=1,167). Baseline characteristics, maternal complications, and neonatal outcomes were compared. Multivariate logistic regression was performed to identify independent risk factors. Results Univariate analysis revealed significant intergroup differences in the incidence of gestational diabetes mellitus (GDM) and preterm birth. The GDM rate was highest in the spontaneous reduction group (26.92%), followed by the surgical reduction group (19.53%) and singleton controls (15.94%, P = 0.003). Preterm birth also differed significantly across groups (19.23% vs 14.06% vs 11.83%, P = 0.024). No group differences were detected for hypertensive disorders of pregnancy, placental complications, or congenital birth defects. After adjusting for maternal age, pre-pregnancy BMI, embryo type, No. of embryos transferred and embryo stage, multivariate logistic regression showed that surgical reduction ( OR = 1.22, 95%CI 0.98-1.52, P = 0.069) and spontaneous reduction ( OR = 1.39, 95%CI 0.98-1.98, P = 0.067) were not independent risk factors for GDM. Advanced maternal age ( OR = 1.12, 95%CI 1.01-1.23, P = 0.028) and elevated pre-pregnancy BMI ( OR = 1.11, 95%CI 1.01-1.21, P = 0.030) were the only independent predictors of GDM. For preterm birth, both surgical reduction ( OR = 1.35, 95%CI 1.09-1.68, P = 0.007) and spontaneous reduction ( OR = 1.72, 95%CI 1.20-2.45, P = 0.003) were independently associated with higher odds of preterm birth. Although the adjusted OR was numerically higher for spontaneous reduction than for surgical reduction, a direct comparison between the two methods showed no statistically significant difference. Conclusion In ART singleton live births, a history of fetal reduction (surgical or spontaneous) was not independently associated with GDM, but both reduction modalities were independently associated with higher odds of preterm birth.