title: The effect of prematurity on vaginal birth after cesarean delivery: success and maternal morbidity.
abstract: OBJECTIVE
  We sought to compare vaginal birth after cesarean (VBAC) success and uterine rupture rates between preterm and term gestations in women with a history of one prior cesarean delivery. Our hypothesis was that preterm women undergoing VBAC were more likely to be successful and have a lower rate of complications than term women undergoing VBAC.
  
  
  METHODS
  We reviewed medical records of women with a history of a cesarean delivery who either attempted a VBAC or underwent a repeat cesarean delivery from 1995 through 2000 in 17 community and university hospitals. We collected information on demographics, medical and obstetric history, complications, and outcome of the index pregnancy. The primary analysis was limited to women with singleton gestations and one prior cesarean delivery. Statistical analysis consisted of bivariate and multivariable techniques.
  
  
  RESULTS
  Among the 20,156 patients with one prior cesarean delivery, 12,463 (61%) attempted a VBAC. Mean gestational ages for the term and preterm women were 39.2 weeks and 33.9 weeks of gestation, respectively. The VBAC success rates for the term and preterm groups were 74% and 82%, respectively (P < .001). Multivariable analysis showed that the VBAC success was higher (adjusted odds ratio 1.54, 95% confidence interval 1.27-1.86) in preterm gestations. A decreased risk of rupture among preterm gestations was suggested in these results (adjusted odds ratio 0.28, 95% confidence interval 0.07-1.17; P = .08).
  
  
  CONCLUSIONS
  Preterm patients undergoing a VBAC have higher success rates when compared with term patients undergoing a VBAC. Preterm patients undergoing VBAC may have lower uterine rupture rates.
authors.affiliation: Division of Maternal Fetal Medicine, Department of Obstetrics & Gynecology, University of Pennsylvania Health System, Philadelphia, Pennsylvania 19104, USA. jquinones@mail.obgyn.upenn.edu
authors.forename: Joanne N
authors.initials: JN
authors.lastname: Quiñones
authors.forename: David M
authors.initials: DM
authors.lastname: Stamilio
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Paré
authors.forename: Jeffrey F
authors.initials: JF
authors.lastname: Peipert
authors.forename: Erika
authors.initials: E
authors.lastname: Stevens
authors.forename: George A
authors.initials: GA
authors.lastname: Macones
mesh_terms: D017604:Cesarean Section, Repeat / Q000009:adverse effects; D005260:Female; D005865:Gestational Age; D006801:Humans; D007752:Obstetric Labor, Premature; D011247:Pregnancy; D011248:Pregnancy Complications; D012307:Risk Factors; D014597:Uterine Rupture / Q000209:etiology; D016064:Vaginal Birth after Cesarean / Q000009:adverse effects