Maternal obesity and contraction strength in the first stage of labor.

OBJECTIVE: The purpose of this study was to determine whether maternal obesity is associated with cesarean delivery and decreased contraction strength in the first stage of labor. STUDY DESIGN: We studied a retrospective cohort of women who delivered within a single healthcare system from 2007-2009; we included 5410 women with an intrauterine pressure catheter during the last 2 hours of the first stage of labor and who either had a vaginal delivery or cesarean delivery for dystocia. Logistic regression was used to determine how body mass index was associated with cesarean delivery or mean Montevideo units of ≥200. RESULTS: Although obese women were at significantly greater odds of cesarean delivery than normal-weight women (odds ratio, 2.4; 95% confidence interval, 1.9-3.1), they were equally able to achieve Montevideo units of ≥200. Among women with a vaginal delivery, obese women had a longer first stage of labor compared with normal-weight women (597 vs 566 min; P = .003). CONCLUSION: Obese women have longer labors but are equally able to achieve adequate Montevideo units as normal-weight women.