Contemporary labor patterns: the impact of maternal body mass index

Objective We sought to compare labor patterns by body mass index (BMI). Study Design A total of 118,978 gravidas with a singleton term cephalic gestation were studied. Repeated-measures analysis constructed mean labor curves by parity and BMI categories for those who reached 10 cm. Interval-censored regression analysis determined median traverse times, adjusting for covariates in vaginal deliveries and intrapartum cesareans. Results In the labor curves, the time difference to reach 10 cm was 1.2 hours from the lowest to highest BMI category for nulliparas. Multiparas entered active phase by 6 cm, but reaching this point took longer for BMI ≥40.0 (3.4 hours) compared to BMI .05) but decreased as BMI increased for multiparas ( P < .001). Conclusion Labor proceeds more slowly as BMI increases, suggesting that labor management be altered to allow longer time for these differences.