title: Normal first stage of preterm labor.
abstract: OBJECTIVE
  To compare first-stage labor patterns in women in preterm labor to those in labor at term.
  
  
  METHODS
  We performed a retrospective cohort study of consecutive women admitted from 2004 to 2008 with viable (≥ 24 weeks) vertex singleton gestations who reached the second stage of labor. Labor curves for preterm and term labor were created using a repeated-measures analysis with polynomial modeling. Interval-censored regression was used to estimate and compare median time of progression of labor. Multivariable analyses were performed to adjust for smoking, obesity (body mass index ≥ 30), induction, and nulliparity. The adjusted model was stratified by parity and induction of labor.
  
  
  RESULTS
  Of 5,612 consecutive births, 224 were preterm (<37 weeks) and 5,388 were term (≥ 37 weeks). Preterm first-stage labor progressed significantly faster than term labor (median time 4 to 10 cm: 3.3 hours versus 4.5 hours, p < 0.01). When stratified by parity, preterm labor progressed significantly more rapidly than term labor in both nulliparous and multiparous women (median time 4 to 10 cm: 3.7 hours versus 4.9 hours [p = 0.04] in nulliparous women and 2.5 hours versus 4.3 hours [p = 0.01] in multiparous women).
  
  
  CONCLUSIONS
  Women in preterm labor progress more rapidly through the first stage of labor than women at term.
authors.affiliation: Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Janine E
authors.initials: JE
authors.lastname: Spain
authors.affiliation: Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Methodius
authors.initials: M
authors.lastname: Tuuli
authors.affiliation: Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, Oregon.
authors.forename: Aaron B
authors.initials: AB
authors.lastname: Caughey
authors.affiliation: Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Roehl
authors.affiliation: Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Qiuhong
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Alison G
authors.initials: AG
authors.lastname: Cahill
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D015331:Cohort Studies; D004420:Dystocia / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007747:Labor Stage, First / Q000502:physiology*; D007751:Labor, Induced; D015233:Models, Statistical; D015999:Multivariate Analysis; D009765:Obesity; D007752:Obstetric Labor, Premature / Q000503:physiopathology*; D010298:Parity; D011247:Pregnancy; D012044:Regression Analysis; D012189:Retrospective Studies; D012907:Smoking; D013997:Time Factors; D055815:Young Adult