title: Evaluation of the labor curve in nulliparous Japanese women.
abstract: OBJECTIVE
  We sought to compare Japanese nulliparous labor progression with Friedman's classic 1955 curve and Zhang's 2002 curve.
  
  
  METHODS
  We developed a labor curve using retrospective record reviews of 2369 Japanese nulliparas, at term, spontaneous labor onset and singleton vertex deliveries of normal birth weight infants.
  
  
  RESULTS
  The new Japanese Suzuki-Horiuchi labor curve with slower cervical dilation in the active phase was like Zhang's and differed from Friedman's curve. Labor length was approximately 5 hours occurring between 4-10 cm compared with Friedman's 2.5 hours and Zhang's 5.5 hours. Even at 10-cm dilation, labor lasted >2 hours at the 95th percentile of time interval.
  
  
  CONCLUSIONS
  Similar to Zhang's curve, the Suzuki-Horiuchi curve was smooth and more gradually sloped than Friedman's curve. Appraise "arrested or protracted labor" with these slower labor curves in mind using Friedman's curve cautiously.
authors.affiliation: Department of Nursing, Kyorin University Hospital, Tokyo, Japan.
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Suzuki
authors.forename: Shigeko
authors.initials: S
authors.lastname: Horiuchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohtsu
mesh_terms: D000293:Adolescent; D000328:Adult; D004363:Drug Utilization; D005113:Extraction, Obstetrical / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007564:Japan; D007743:Labor, Obstetric; D008423:Maternal Age; D010120:Oxytocics / Q000627:therapeutic use; D010121:Oxytocin / Q000627:therapeutic use; D010298:Parity; D011247:Pregnancy; D012189:Retrospective Studies; D013997:Time Factors; D055815:Young Adult
chemical_list: D010120:Oxytocics; D010121:Oxytocin