title: Contemporary labor patterns: the impact of maternal body mass index.
abstract: OBJECTIVE
  We sought to compare labor patterns by body mass index (BMI).
  
  
  METHODS
  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 <25.0 (2.4 hours). Progression by centimeter (P < .001 for nulliparas) and from 4-10 cm (P < .001 for nulliparas and multiparas) increased as BMI increased. Second stage length, with and without an epidural, was similar among BMI categories for nulliparas (P > .05) but decreased as BMI increased for multiparas (P < .001).
  
  
  CONCLUSIONS
  Labor proceeds more slowly as BMI increases, suggesting that labor management be altered to allow longer time for these differences.
authors.affiliation: Department of Obstetrics and Gynecology, University of Illinois at Chicago, Chicago, IL, USA. Mkomin1@uic.edu
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Kominiarek
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Paul
authors.initials: P
authors.lastname: Vanveldhuisen
authors.forename: James
authors.initials: J
authors.lastname: Troendle
authors.forename: Julie
authors.initials: J
authors.lastname: Beaver
authors.forename: Judith U
authors.initials: JU
authors.lastname: Hibbard
mesh_terms: D000328:Adult; D001823:Body Composition; D015992:Body Mass Index; D036861:Delivery, Obstetric; D005260:Female; D006801:Humans; D007743:Labor, Obstetric / Q000502:physiology*; D010298:Parity / Q000502:physiology; D036801:Parturition / Q000502:physiology*; D011247:Pregnancy; D014481:United States