Influence of uterine fibroid size on perinatal and neonatal outcomes: a single-centre cohort of 651 pregnancies
To evaluate the impact of fibroid size on maternal and neonatal outcomes, determine whether a dose-response pattern exists across size categories (< 5 cm, 5-10 cm, > 10 cm), and identify a threshold at which pregnancy risk increases significantly. This retrospective cohort study included 651 pregnant women with sonographically confirmed uterine fibroids. Participants were stratified into three groups based on the maximum diameter of the largest fibroid: <5 cm, 5-10 cm, and > 10 cm. Outcomes assessed included preterm birth, PPROM, malpresentation, caesarean delivery, postpartum haemorrhage (PPH), fetal growth restriction (FGR), NICU admission, miscarriage, surgical outcomes such as operative time and blood loss, and a composite adverse perinatal outcome (CAPO). Logistic regression analysis was performed to identify variables independently associated with CAPO. Adverse events rose stepwise with fibroid size. Preterm birth occurred in 12.3%, 24.1% and 36.1% of the size groups (p < 0.001); PPROM in 2.5%, 10.6% and 13.9% (p < 0.001); malpresentation in 13.3%, 28.6% and 47.2% (p < 0.001). Caesarean deliveries were 56.6%, 67.3% and 92.1%, while PPH rose from 1.3 to 30.6% (both p < 0.001). Operative blood loss and time likewise increased with diameter. Neonatally, mean birthweight declined (3150 g, 2995 g, 2870 g; p = 0.003); NICU admission rose from 13.5 to 34.1% (p < 0.001), and CAPO from 14.8 to 35.1% (p < 0.001). Multivariate analysis showed that fibroids > 5 cm independently predicted CAPO (aOR: 1.84 for 5-10 cm; 3.78 for > 10 cm), while maternal age, parity, IVF were not significant. Descriptive subgroup analysis revealed longer operative times and greater blood loss in women with multiple, cervical, or combined-type fibroids. Fibroid diameter emerged as a key determinant of obstetric and neonatal risk. Lesions > 5 cm, particularly > 10 cm, were associated with markedly increased rates of maternal haemorrhage, preterm birth, and neonatal morbidity. Such pregnancies should be managed as high-risk, with enhanced antenatal surveillance and individualized delivery planning.