(1129) Evaluating the Duration of Labor in Patients Undergoing TOLAC

To examine labor differences in patients that had an uncomplicated vaginal birth after cesarean (VBAC) and patients that had a complicated VBAC or failed trial of labor after cesarean (TOLAC).

Study Design:

This was a secondary analysis of patients at > 37 weeks’ gestation with a history of one prior cesarean section, no prior vaginal births that underwent a TOLAC (N=5274) from the Consortium of Safe Labor (2002-2008). Length of labor was compared between patients that had an uncomplicated VBAC and patients that had a complicated VBAC or failed TOLAC. A complicated VBAC was defined as patients that had an estimated blood loss (EBL) of greater than 1000 mL, neonatal intensive care unit (NICU) admission, 5-minute APGAR score < 7, or 3^rd or 4^th degree laceration. A failed TOLAC was defined as a patient that had an intrapartum repeat cesarean section. Weibull-based accelerated failure time regression model was used to examine the interval censored time of cervical dilation from 1 cm to the next by calculating median (5^th- 95^th percentile) transverse times (hour). A Cox regression model was used to evaluate the length of the second stage.

Results: Of the 5274 patients that underwent a TOLAC, an uncomplicated VBAC occurred in 1400 (26.5%), a complicated VBAC occurred in 194 (3.7%) of patients and a failed TOLAC occurred in 3680 (72.2%) patients. Patients that had uncomplicated VBAC had a tendency for shorter laboring time with progression from 1-6 cm taking 8 hours (IQR 2.4-15.9) compared to 13.7 hours (IQR 4.1-27.1) in patients that had a complicated VBAC or failed TOLAC (p=.10). Compared to patients that had an uncomplicated VBAC, patients that had a complicated VBAC or failed TOLAC (HR 0.67, 0.95% CI 0.57-0.79), older patients (HR 0.97; 0.95% CI 0.96-0.98), and patients that used an epidural (HR 0.71; 0.95% CI 0.62-0.81) were more likely experience a longer second stage.

Conclusion:

Although not statistically significant, a longer duration in the first and second stage of labor may increase the risk of having a complicated VBAC or failed TOLAC.