Influence of uterine fibroid size on perinatal and neonatal outcomes: a single-centre cohort of 651 pregnancies.

Abstract

Objective: 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.

Methods: 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.

Results: 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.

Conclusion: 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.