Erika Stevens

Short interpregnancy interval: risk of uterine rupture and complications of vaginal birth after cesarean delivery.

OBJECTIVE: To investigate whether short or long interpregnancy interval is associated with uterine rupture and other major maternal morbidities in women who attempt vaginal birth after cesarean delivery (VBAC). METHODS: We performed a secondary analysis of a U.S. multi-center, record-based, retrospective cohort study of 13,331 pregnant women, identified by a validated International Classification of Disease, 9th Revision, code search, with at least one prior cesarean delivery, who attempted VBAC between 1995 and 2000. We performed univariable and multivariable logistic regression analyses to evaluate the association between long or short interpregnancy interval and three maternal outcomes: 1) uterine rupture, 2) composite major morbidity (including rupture, bladder or bowel injury, and uterine artery laceration), and 3) blood transfusion. We evaluated short interpregnancy interval with cutoffs at less than 6, less than 12, and less than 18 months between prior delivery and conception and defined long interval as 60 months or more. RESULTS: A total of 128 cases (0.9%) of uterine rupture occurred, and 286 (2.2%), 1,109 (8.3%), 1,741 (13.1%), and 2,631 (19.7%) women had interpregnancy intervals of less than 6, 6–11, 12–17, and 60 months or more, respectively. An interval less than 6 months was associated with increased risk of uterine rupture (adjusted odds ratio [aOR] 2.66, 95% confidence interval [CI] 1.21–5.82), major morbidity (aOR 1.95, 95% CI 1.04–3.65), and blood transfusion (aOR 3.14, 95% CI 1.42–6.95). Long interpregnancy interval was not associated with an increase in major morbidity. CONCLUSION: Short interpregnancy interval increases risk for uterine rupture and other major morbidities twofold to threefold in VBAC candidates. LEVEL OF EVIDENCE: II

Predicting failure of a vaginal birth attempt after cesarean delivery.

OBJECTIVE: To identify a group of clinical factors that could be used to accurately predict failure in women attempting vaginal birth after cesarean (VBAC). METHODS: We conducted a planned secondary analysis of a retrospective cohort study of women who were offered VBAC from 1996 to 2000 in 17 community and university hospitals. We collected information about maternal history and outcomes of the index pregnancy. We used univariable and multivariable statistical methods to develop a multivariable prediction model for the outcome of VBAC failure. RESULTS: A total of 13,706 patients attempted VBAC, with a failure rate of 24.5%. Six variables were significantly associated with VBAC failure in our final logistic regression model: gestational age at delivery, maternal age, maternal race, labor type (spontaneous, augmented, or induced), history of vaginal delivery, and cephalopelvic disproportion or failed induction (combined variable) as prior cesarean indication. The area under the receiver operating characteristics curve is 0.717. To achieve a sensitivity of approximately 75%, a false-positive rate of approximately 40% would result. CONCLUSION: Our results indicate that significant clinical variables (prelabor and labor) cannot reliably predict VBAC failure. LEVEL OF EVIDENCE: II

Safety and Efficacy of Vaginal Birth After Cesarean Attempts at or Beyond 40 Weeks of Gestation

OBJECTIVE: To compare rates of vaginal birth after cesarean (VBAC) failure and major complications in women attempting VBAC before and after the estimated date of delivery (EDD) METHODS: This was a 5-year retrospective cohort study in 17 university and community hospitals of women with at least 1 prior cesarean delivery. Women who attempted VBAC before the EDD were compared with those at or beyond 40 weeks of gestation. Logistic regression analyses were performed to assess the relationship between delivery beyond the EDD and VBAC failure or complication rate. RESULTS: A total of 11,587 women in the cohort attempted VBAC. Women past 40 weeks of gestation were more likely to have a failed VBAC. After controlling for confounders, the increased risk of a failed VBAC beyond 40 weeks remained significant (31.3% compared with 22.2%, odds ratio 1.36, 95% confidence interval 1.24–1.50). The risk of uterine rupture (1.1% compared with 1.0%) or overall morbidity (2.7% compared with 2.1%) was not significantly increased in the women attempting VBAC beyond the EDD. When the cohort was defined as 41 weeks or more of gestation, the risk of a failed VBAC was again significantly increased (35.4% compared with 24.3%, odds ratio 1.35, 95% confidence interval 1.20–1.53), but the risk of uterine rupture or overall morbidity was not increased. CONCLUSION: Women beyond 40 weeks of gestation can safely attempt VBAC, although the risk of VBAC failure is increased. LEVEL OF EVIDENCE: II-2

Minor trauma in pregnancy : is the evaluation unwarranted?

OBJECTIVE The purpose of this study was to examine the rate of and risks for abruption and adverse pregnancy outcome after minor trauma in pregnancy. STUDY DESIGN This is a 3-year prospective cohort study of patients after noncatastrophic trauma. Data collected included maternal demographics and history, trauma mechanism, and pregnancy outcome. Examination, lab tests including Kleihauer-Betke (KB), and a minimum of 4 hours of fetal monitoring were performed. The primary outcomes were placental abruption and a composite pregnancy morbidity outcome. Univariate and bivariate analysis were performed. RESULTS Of the 317 patients evaluated for minor trauma, 9 had a positive KB test (2.8%). Delivery information was available on 256 (81%) patients, and there was 1 placental abruption. The 49 cases (19.4%) of composite outcome could not be predicted. CONCLUSION Perhaps it is time to reevaluate the extensive evaluations often done after minor trauma in pregnancy, particularly because none of the commonly used objective measures are predictive of adverse outcomes.

Racial disparity in the success and complications of vaginal birth after cesarean delivery

OBJECTIVE: To determine if race is associated with election to attempt vaginal birth after cesarean delivery (VBAC), VBAC success, and maternal morbidities associated with VBAC. METHODS: A retrospective, multi-center cohort study was conducted of women with a history of at least one prior cesarean delivery. Data were obtained on maternal demographics, medical history, antepartum and intrapartum course, delivery mode, and maternal outcomes. This analysis examines the association between race and the choice to have VBAC and compares the rates of VBAC success and maternal morbidity, including uterine rupture, and a composite morbidity outcome (uterine rupture, bladder and bowel injury, and artery laceration) across race groups. Race was determined by patient self-report. Univariable and multivariable analyses were performed to assess the independent association of race and clinical outcomes. RESULTS: The cohort included 25,005 patients with at least one prior cesarean delivery. In unadjusted and multivariable analysis, black patients were more likely to undertake a trial of labor than patients of other races, and slightly more likely to experience a failure of VBAC attempt. However, black women who attempt VBAC are 40% less likely to sustain a uterine rupture (0.6% compared with 1.1%) than other racial groups, even after adjusting for relevant potentially confounding variables. CONCLUSION: Despite increased rates of VBAC attempt and VBAC failure among black women as compared with other racial groups, black women are significantly less likely to experience a uterine rupture. It is unclear whether this discrepancy in magnitudes of risks and benefits across race associated with VBAC trials is attributable to selection bias or inherent racial differences. LEVEL OF EVIDENCE: II

The effect of prematurity on vaginal birth after cesarean delivery: success and maternal morbidity.

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). CONCLUSION: 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. LEVEL OF EVIDENCE: II-2