Prospective study of the effect of maternal body mass index on labor progress in nulliparous women in Egypt

Objective: To evaluate the impact of maternal body mass index (BMI, calculated asweight in kilograms divided by the square of height in meters) on labor progress in nulliparous women. Methods: The present prospective cohort study enrolled primigravidae admitted to Kasr Al Ainy hospital, Cairo University, Egypt, during active labor between February 1, 2016, and February 28, 2017. Patients were classified into three equal groups using their BMI at admission: underweight (<18.5), normal weight (18.5-29.9), and obese (30). The primary outcome was the rate of cervical dilatation; secondary outcomes included the duration of the second stage of labor, neonatal delivery weight, and the mode of delivery. Results: Among the 600 primigravidae enrolled (200 in each group), significant differences were recorded in the rates of cervical dilatation (P<0.001), and the duration of the active labor phase (P<0.001) and the whole of labor (P<0.001); in the obese group, the cervical dilatation rate was lowest and the durations of the active phase of labor and the whole of labor were longer. The incidence of intrapartum cesarean delivery (P<0.001) and neonatal delivery weight (P<0.001) also differed between the groups; both were highest in the obese group. Conclusions: Patterns in labor progress, including cervical dilatation rate and labor duration, differed among patients with different BMI.