Fetal growth in PCOS pregnancies: dynamic evidence of restriction and the modifying role of ART

Background Polycystic ovary syndrome (PCOS), the most prevalent endocrine disorder among women of reproductive age, is associated with adverse pregnancy outcomes. However, the dynamic trajectory of fetal growth in PCOS pregnancies remains inadequately characterized. Objective This study aimed to longitudinally assess fetal growth in PCOS pregnancies and evaluate whether assisted reproductive technology (ART) modifies associated fetal growth restriction. Methods In this prospective multicenter cohort study (UNIHOPE; NCT03220750), 12,189 advanced maternal age pregnancies (364 with Rotterdam-diagnosed PCOS) underwent longitudinal fetal biometry in the second and third trimesters following ISUOG guidelines. Z-scores were derived using the study’s advanced-age reference, adjusting for gestational age and sex. Generalized linear models were adjusted for maternal demographics, lifestyle factors, and gestational diabetes mellitus, with subgroup analyses stratified by ART conception. Results Among 12,189 advanced maternal age pregnancies (364 PCOS), PCOS fetuses showed reduced second-trimester Z-scores for femur length (MD: −0.13; 95% CI, −0.25 to −0.02) and head circumference (MD: −0.14; 95% CI, −0.23 to −0.04), with third-trimester deficits extending to biparietal diameter (MD: −0.18) and abdominal circumference (MD: −0.16). Birth length (MD: −0.16) and weight (MD: −0.13) Z-scores were lower in PCOS neonates. Growth restriction was evident only in spontaneous conceptions, with no significant differences in ART-conceived pregnancies. Findings were robust to GDM adjustment. Discussion Fetal growth restriction in PCOS pregnancies is detectable from the second trimester and persists to delivery. ART conception appears to mitigate this restriction, yielding fetal growth parameters comparable to the reference population. These findings underscore the necessity of dynamic ultrasound surveillance in PCOS pregnancies and highlight a potential protective role of ART in perinatal outcomes. Clinical trial registration https://clinicaltrials.gov , identifier NCT03220750.