Effect of previous vaginal delivery on the risk of uterine rupture during a subsequent trial of labor.
OBJECTIVE
We examined the effect of prior vaginal delivery on the risk of uterine rupture in pregnant women undergoing a trial of labor after prior cesarean delivery.


METHODS
The medical records of all pregnant women with a history of cesarean delivery who attempted a trial of labor during a 12-year period at a single center were reviewed. For the current analysis, the study population was limited to term pregnancies. The effect of previous vaginal delivery on the risk of uterine rupture during a subsequent trial of labor was evaluated. Separate analyses were performed for women with a single previous cesarean delivery and for those with >1 prior cesarean delivery. For each of these subgroups, the rate of uterine rupture among women who had > or =1 prior vaginal delivery was compared with the rate among women with no prior vaginal delivery. Logistic regression analysis was used to examine the associations with control for confounding factors.


RESULTS
Of 3783 women with 1 prior scar, 1021 (27.0%) also had > or =1 prior vaginal delivery. During a subsequent trial of labor, the rate of uterine rupture was 1.1% among pregnant women without prior vaginal delivery and 0.2% among pregnant women with prior vaginal delivery (P =.01). Logistic regression analysis controlling for duration of labor, induction, birth weight, maternal age, year of birth, epidural analgesia, and oxytocin augmentation indicated that, among women with a single scar, those with a prior vaginal delivery had a risk of uterine rupture that was one fifth that of women without a previous vaginal delivery (odds ratio, 0.2; 95% confidence interval, 0.04-0.8). In the group of 143 pregnant women with >1 previous cesarean delivery, women with a prior vaginal delivery had a somewhat lower risk of uterine rupture (3.9% vs 2.5%; adjusted odds ratio, 0.6; 95% confidence interval, 0.01-6.7). This difference was not statistically significant.


CONCLUSIONS
Among women with 1 prior cesarean delivery undergoing a subsequent trial of labor, those with a prior vaginal delivery were at substantially lower risk of uterine rupture than women without a previous vaginal delivery.
Zelop
C M
CM
Department of Obstetrics and Gynecology, Lenox Hill Hospital, New York, NY 10021-1988, USA.
Shipp
T D
TD
Repke
J T
JT
Cohen
A
A
Lieberman
E
E
D005260:Female; D006801:Humans; D011247:Pregnancy; D012307:Risk Factors; D014219:Trial of Labor; D014597:Uterine Rupture / Q000209:etiology*; D016064:Vaginal Birth after Cesarean / Q000009:adverse effects*