title: Risk of uterine rupture associated with an interdelivery interval between 18 and 24 months.
abstract: OBJECTIVE
  To estimate the association between interdelivery interval and uterine rupture in women with a previous cesarean delivery.
  
  
  METHODS
  Secondary analysis was performed in a retrospective cohort study of women who underwent a trial of labor after undergoing a previous cesarean delivery. Only singleton pregnancies with a trial of labor at term were included. Women with two or more previous cesarean deliveries or with a vaginal delivery between the cesarean delivery and the trial of labor were excluded. The rates of uterine rupture were compared among women with interdelivery intervals 24 months or longer (controls), 18-24 months, and fewer than 18 months. The chi2 test and multivariable logistic regression analysis were conducted. A P value of less than .05 was considered significant.
  
  
  RESULTS
  A total of 1,768 women were included: 1,323 (74.8%) were 24 months or longer, 257 (14.5%) were 18-23 months, and 188 (10.6%) were fewer than 18 months. The rates of uterine rupture were 1.3%, 1.9%, and 4.8%, respectively (P=.003). After adjustment for confounding factors, an interdelivery interval shorter than 18 months was associated with a significant increase of uterine rupture (odds ratio [OR], 3.0; 95% confidence interval [CI], 1.3-7.2), whereas an interdelivery interval between 18 to 24 months was not (OR, 1.1; 95% CI, 0.4-3.2).
  
  
  CONCLUSIONS
  An interdelivery interval shorter than 18 months, but not between 18 and 24 months, should be considered as a risk factor for uterine rupture.
authors.affiliation: From the Department of Obstetrics and Gynaecology, Faculty of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Québec, Canada; and Department of Obstetrics and Gynaecology, Faculty of Medicine, Hôpital Sainte-Justine, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Bujold
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Gauthier
mesh_terms: D000328:Adult; D001721:Birth Intervals; D005260:Female; D006801:Humans; D016015:Logistic Models; D011247:Pregnancy; D012307:Risk Factors; D014219:Trial of Labor; D014597:Uterine Rupture / Q000453:epidemiology*; D016064:Vaginal Birth after Cesarean / Q000706:statistics & numerical data*
references.citation: Bujold E, Gauthier RJ. Neonatal morbidity associated with uterine rupture: what are the risk factors? Am J Obstet Gynecol 2002;186:311–4.
references.citation: Guise JM, McDonagh MS, Osterweil P, Nygren P, Chan BK, Helfand M. Systematic review of the incidence and consequences of uterine rupture in women with previous caesarean section. BMJ 2004;329:19–25.
references.citation: Esposito MA, Menihan CA, Malee MP. Association of interpregnancy interval with uterine scar failure in labor: a case-control study. Am J Obstet Gynecol 2000;183:1180–3.
references.citation: Shipp TD, Zelop CM, Repke JT, Cohen A, Lieberman E. Interdelivery interval and risk of symptomatic uterine rupture. Obstet Gynecol 2001;97:175–7.
references.citation: Bujold E, Mehta SH, Bujold C, Gauthier RJ. Interdelivery interval and uterine rupture. Am J Obstet Gynecol 2002;187:1199–202.
references.citation: Stamilio DM, DeFranco E, Pare E, Odibo AO, Peipert JF, Allsworth JE, et al. Short interpregnancy interval: risk of uterine rupture and complications of vaginal birth after cesarean delivery. Obstet Gynecol 2007;110:1075–82.
references.citation: Vaginal birth after previous cesarean. ACOG Practice Bulletin No. 54. American College of Obstetricians and Gynecologists. Obstet Gynecol 2004;104:203–12.
references.citation: Guidelines for vaginal birth after previous caesarean birth. SOGC Clinical Practice Guidelines No. 155. Society of Obstetricians and Gynaecologists of Canada. Int J Gynaecol Obstet 2005;89:319–31.
references.citation: Bujold E, Bujold C, Hamilton EF, Harel F, Gauthier RJ. The impact of a single-layer or double-layer closure on uterine rupture. Am J Obstet Gynecol 2002;186:1326–30.
references.citation: Bujold E, Blackwell SC, Gauthier RJ. Cervical ripening with transcervical foley catheter and the risk of uterine rupture. Obstet Gynecol 2004;103:18–23.
references.citation: Hendler I, Bujold E. Effect of prior vaginal delivery or prior vaginal birth after cesarean delivery on obstetric outcomes in women undergoing trial of labor. Obstet Gynecol 2004;104:273–7.
references.citation: Bujold E, Blackwell SC, Hendler I, Berman S, Sorokin Y, Gauthier RJ. Modified Bishop's score and induction of labor in patients with a previous cesarean delivery. Am J Obstet Gynecol 2004;191:1644–8.
references.citation: Jastrow N, Roberge S, Gauthier R, Laroche L, Duperron L, Brassard N, et al. Effect of birth weight on adverse obstetric outcomes in vaginal birth after cesarean delivery. Obstet Gynecol 2010;115:338–43.
references.citation: Huang WH, Nakashima DK, Rumney PJ, Keegan KA Jr, Chan K. Interdelivery interval and the success of vaginal birth after cesarean delivery. Obstet Gynecol 2002;99:41–4.
references.citation: Ridgeway JJ, Weyrich DL, Benedetti TJ. Fetal heart rate changes associated with uterine rupture. Obstet Gynecol 2004;103:506–12.
references.citation: Grobman WA, Lai Y, Landon MB, Spong CY, Leveno KJ, Rouse DJ, et al. Prediction of uterine rupture associated with attempted vaginal birth after cesarean delivery. Am J Obstet Gynecol 2008;199:30.e1–5.
references.citation: Bujold E, Jastrow N, Simoneau J, Brunet S, Gauthier RJ. Prediction of complete uterine rupture by sonographic evaluation of the lower uterine segment. Am J Obstet Gynecol 2009;201:320.e1–6.