Poster session II Diabetes, labor, medical-surgical-disease, obstetric quality & safety, prematurity, ultrasound-imaging: Abstracts 237 – 386| Volume 206, ISSUE 1, SUPPLEMENT , S149-S150, January 01, 2012

314: Obese women have longer duration of the first stage of labor


      While many studies have identified maternal obesity as a risk factor for cesarean delivery, the effect of obesity on the progress of labor is less clear. We aimed to estimate the effects of obesity on the duration and progression of the first stage of labor.

      Study Design

      We performed a retrospective cohort study of labor progression among 5204 consecutive parturients with singleton term pregnancies (≥ 37 weeks) and vertex presentation who completed the first stage of labor. Two comparison groups were defined by body mass index (BMI) 4000g, and prior cesarean.


      The labor curves indicate longer duration and slower progression of the first stage of labor among women with BMI>30, both overall and when stratified by parity (Figure). Multivariable interval-censored regression analysis confirmed significantly longer duration (4 to 10cm: 4.6 versus 4.0 hours, p<0.001) and slower progression of cervical dilation from 4 to 6cm (2.4 versus 1.9 hours, p<0.001, with a range of 0.5-10.7 hours) among women with BMI ≥30 after adjusting for confounders (Table).
      Tabled 1
      Table thumbnail grt37


      The overall duration is longer and progression of the early part of the first stage of labor is slower in obese women. This suggests that obesity should be considered in defining norms for management of labor particularly in the early part of the first stage.