Does a larger estimated fetus compared with prior birthweight increase the risk of cesarean delivery after a prior vaginal birth?
摘要
To evaluate whether an increase in estimated fetal weight (EFW) relative to the birthweight of a prior vaginal delivery is associated with intrapartum cesarean delivery (CD) or other adverse obstetric outcomes.
MethodsThis retrospective cohort study included patients with two consecutive term singleton deliveries (2014–2025). All had a vaginal first delivery and underwent a trial of labor in the second pregnancy. Patients were categorized by the difference between EFW and prior birthweight: higher (> 15%) and similar (-15% to 15%). The primary outcome was intrapartum CD. Multivariable logistic regression adjusted for clinically relevant confounders. Subgroup analysis stratified by EFW (< 3500 vs. ≥ 3500 g) evaluated the effect of absolute fetal size.
ResultsThe primary analysis included 2849 patients: 2265 in the similar-weight group and 584 in the higher-weight group. The crude intrapartum CD rate was higher in the higher-weight group (5.3% vs 3.0%, p = 0.006). After adjustment, weight difference was not independently associated with CD (adjusted odds ratio [aOR] 1.43; 95% CI 0.91–2.27; p = 0.12). In subgroup analysis, among patients with EFW ≥ 3500 g, a trend toward increased CD risk was observed in the higher-weight group (aOR 1.68, 95% CI 0.94–2.99, p = 0.08).
ConclusionAn increase in EFW relative to prior birthweight was not independently associated with intrapartum CD among patients with a prior vaginal delivery. Among patients with larger absolute EFW, a non-significant trend toward increased intrapartum CD risk was observed, a finding that warrants future investigation. These findings suggest that interpregnancy weight differences alone should not guide delivery planning in otherwise uncomplicated pregnancies.