title: Contemporary patterns of spontaneous labor with normal neonatal outcomes.
abstract: OBJECTIVE
  To use contemporary labor data to examine the labor patterns in a large, modern obstetric population in the United States.
  
  
  METHODS
  Data were from the Consortium on Safe Labor, a multicenter retrospective study that abstracted detailed labor and delivery information from electronic medical records in 19 hospitals across the United States. A total of 62,415 parturients were selected who had a singleton term gestation, spontaneous onset of labor, vertex presentation, vaginal delivery, and a normal perinatal outcome. A repeated-measures analysis was used to construct average labor curves by parity. An interval-censored regression was used to estimate duration of labor, stratified by cervical dilation at admission and centimeter by centimeter.
  
  
  RESULTS
  Labor may take more than 6 hours to progress from 4 to 5 cm and more than 3 hours to progress from 5 to 6 cm of dilation. Nulliparous and multiparous women appeared to progress at a similar pace before 6 cm. However, after 6 cm, labor accelerated much faster in multiparous than in nulliparous women. The 95 percentiles of the second stage of labor in nulliparous women with and without epidural analgesia were 3.6 and 2.8 hours, respectively. A partogram for nulliparous women is proposed.
  
  
  CONCLUSIONS
  In a large, contemporary population, the rate of cervical dilation accelerated after 6 cm, and progress from 4 cm to 6 cm was far slower than previously described. Allowing labor to continue for a longer period before 6 cm of cervical dilation may reduce the rate of intrapartum and subsequent repeat cesarean deliveries in the United States.
authors.affiliation: From the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Georgetown University Hospital, MedStar Health, Washington, DC; Intermountain HealthCare and University of Utah, Salt Lake City, Utah; Baystate Medical Center, Springfield, Massachusetts; Maimonides Medical Center, Brooklyn, New York; Cedars-Sinai Medical Center, Los Angeles, California; Summa Health System, Akron City Hospital, Akron, Ohio; University of Texas Health Science Center at Houston, Houston, Texas; MetroHealth Medical Center, Cleveland, Ohio; University of Miami, Miami, Florida; University of Illinois at Chicago, Chicago, Illinois; Christiana Care Health System, Wilmington, Delaware; Indiana University-Clarian Health, Indianapolis, Indiana; and The EMMES Corporation, Rockville, Maryland.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Helain J
authors.initials: HJ
authors.lastname: Landy
authors.forename: D
authors.initials: D
authors.lastname: Ware Branch
authors.forename: Ronald
authors.initials: R
authors.lastname: Burkman
authors.forename: Shoshana
authors.initials: S
authors.lastname: Haberman
authors.forename: Kimberly D
authors.initials: KD
authors.lastname: Gregory
authors.forename: Christos G
authors.initials: CG
authors.lastname: Hatjis
authors.forename: Mildred M
authors.initials: MM
authors.lastname: Ramirez
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Bailit
authors.forename: Victor H
authors.initials: VH
authors.lastname: Gonzalez-Quintero
authors.forename: Judith U
authors.initials: JU
authors.lastname: Hibbard
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Hoffman
authors.forename: Michelle
authors.initials: M
authors.lastname: Kominiarek
authors.forename: Lee A
authors.initials: LA
authors.lastname: Learman
authors.forename: Paul
authors.initials: P
authors.lastname: Van Veldhuisen
authors.forename: James
authors.initials: J
authors.lastname: Troendle
authors.forename: Uma M
authors.initials: UM
authors.lastname: Reddy
mesh_terms: D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007747:Labor Stage, First; D007748:Labor Stage, Second; D007743:Labor, Obstetric; D010298:Parity; D011247:Pregnancy; D011256:Pregnancy Outcome; D012016:Reference Values