Interdelivery interval and uterine rupture.

OBJECTIVE

The purpose of this study was to measure the impact of the interdelivery interval on uterine rupture during subsequent delivery.

STUDY DESIGN

An observational cohort study was performed to assess the rate of uterine rupture in women with a previous low transverse cesarean delivery and no previous vaginal delivery who undergo a trial of labor from 1988 to 2000 in a tertiary care center. The rate of uterine rupture was measured for each of the following interdelivery intervals: <or=12 months of gestation, 13 to 24 months of gestation, 25 to 36 months of gestation, and >36 months of gestation. Multivariate logistic regression analysis was used to adjust for selected confounding variables.

RESULTS

Of the 1527 women who met the study criteria, the rate of uterine rupture was 4.8% for patients with an interdelivery interval of <or=12 months of gestation, 2.7 % for patients with an interval between 13 and 24 months of gestation, 0.9% for patients with an interval between 25 and 36 months of gestation, and 0.9% for patients with an interval of >36 months of gestation (P =.04). After adjustment for the confounding variables, the odds ratio for uterine rupture in women with an interdelivery interval of <or=24 months of gestation was 2.65 (95% CI, 1.08-6.46) and 4.33 (95% CI, 1.70-10.98) in women with a single-layer closure of the previous uterine incision. The combination of an interdelivery interval of <or=24 months of gestation and a single-layer closure of the previous uterine incision were associated with a rate of uterine rupture of 5.6%.

CONCLUSION

An interdelivery interval of <or=24 months of gestation was associated with a 2- to 3-fold increase in the risk of uterine rupture compared with an interval of >24 months of gestation.