摘要：Objec.ive: To evaluate the assoc.ation between maternal body mass index and obstetric.l outc.me in patients with a prior c.sarean undergoing a trial of labor versus elec.ive repeat c.sarean. Study design: A perinatal database between 1991 and 1997 was used to identify sec.ndipara at term after a previous c.sarean sec.ion. In different groups ac.ording to maternal body mass index, the rates of suc.essful vaginal birth after c.esarean, uterine sc.r separation, and other obstetric.l outc.mes were evaluated. Results: Of 8580 patients with a prior c.sarean, 1862 (21.7%) underwent an elec.ive repeat c.sarean and 6718 (78.3%) underwent a trial of labor. Maternal body mass index c.rrelated inversely with the rate of suc.essful vaginal birth after c.esarean but not with the rate of uterine sc.r separation. After adjustment for c.nfounding fac.ors inc.uding maternal age, birth weight, induc.ion of labor, and preec.ampsia, maternal body mass index remained assoc.ated with a lower rate of suc.essful vaginal birth after c.sarean. c.nc.usion: Maternal body mass index is an independent fac.or assoc.ated with a lower rate of suc.essful vaginal birth after c.sarean.