The effect of gestational age on trial of labor after Cesarean section

Abstract

Objectives: To evaluate the effect of gestational age on the rate of successful vaginal delivery and the rate of uterine rupture in patients undergoing a trial of labor (TOL) after a prior Cesarean delivery.Study design: This was a cohort study including patients with a live singleton fetus undergoing a TOL after a previous low transverse Cesarean delivery between 1988 and 2002. Patients were divided into three groups according to gestational age: 24–36 weeks 6 days, 37–40 weeks 6 days and ≥41 weeks. Obstetric outcomes, including the rates of successful vaginal delivery and symptomatic uterine rupture, were compared between the groups. Multivariate logistic regression analysis was performed to adjust for potential confounding factors.Results: There were 253, 1911 and 329 patients in each group, respectively. In patients with advanced gestational age (≥41 weeks) the rate of uterine rupture was significantly higher (0% vs. 1.0% vs. 2.7%, p=0.006) and the rate of successful vaginal deliveries was significantly lower (83% vs. 76.9% vs. 62.6%, p<0.001). After adjusting for confounding variables, advanced gestational age was associated with a lower rate of successful vaginal delivery (odds ratio 0.68, 95% CI 0.51–0.89), and a higher rate of uterine rupture (odds ratio 2.85, 95% CI 1.27–6.42) when compared to 37–40 weeks 6 days.Conclusion: Advanced gestational age is associated with higher rates of failed TOL and uterine rupture.

• Vaginal birth after cesarean
• Uterine rupture
• Cesarean section
• Gestational age