Given that some hospitals outright refuse to allow women to attempt a VBAC, and the American College of Obstetricians and Gynecologists actually felt it was necessary to dissuade its member OB/GYNs in a policy statement from seeking court orders to force c-section when women refuse, you might assume that the risk of uterine rupture or other complications is extremely high following a previous cesarean. However, new evidence suggests that the actual risk may be lower than is commonly believed.
The October issue of the journal “Obstetrics & Gynecology” includes findings from a large study that followed 39,117 women at multiple medical centers who had a singleton pregnancy and a prior cesarean section. The details of the women’s term vaginal births and c-sections were recorded, along with information on any adverse events. The study was observational, meaning that the researchers didn’t randomize women to one type of birth or another, but simply recorded what happened.
Researchers separated these women into five groups to assess the outcomes, consisting of those undergoing: 1) a trial of labor (with no plans for c-section); 2) elective repeat c-section with no labor; 3) elective repeat c-section after the onset of labor; 4) non-elective (medically indicated) repeat c-section with no labor; 5) non-elective c-section after onset of labor.
A few of the findings:
-Of the trials of labor, 73.3 percent were successful (11,226 successful vaginal births after cesarean of the 15,323 attempted).
-Six maternal deaths occurred, but none were associated with uterine rupture. Five of these occurred in the elective repeat cesarean group, and one was after trial of labor (resulting from hemorrhage).
-While uterine rupture was more common in those with trial of labor (0.74 percent) than in those with elective c-section (0-0.15 percent), rates of overall complications were similar between the groups (5.3 percent for the trial of labor group, compared with 3.4-6.4 percent in the elective c-section groups).
-The rate of uterine rupture was highest in those undergoing a trial of labor, but was <1 percent.
-Among women having repeat cesareans, rates of uterine rupture were highest in those with a medical indication for repeat cesarean and some labor (0.28 percent), and next-highest in those with elective c-section and some labor (0.15 percent).
-The overall risk of serious adverse perinatal outcome was 0.27 percent. The trial of labor group had the highest rate of antepartum stillbirth (0.22 percent) and hypoxic ischemic encephalopathy (0.08 percent) of the five groups, but had lower or similar rates of intrapartum stillbirth and neonatal death compared with some of the other groups.
This study has certain limitations, such as the focus on short-term outcomes - the authors are not able to comment on less immediate postpartum outcomes such as infection, pain, or hospital readmission, or on long-term reproductive health. Previous research suggests that women who have cesarean births are more likely than woman who have vaginal births to experience these less immediate problems. However, it may be a good starting point for talking realistically about the likelihood of complications when women attempt a vaginal birth after cesarean, rather than continuing to rely solely on the "conventional wisdom."
For additional information on cesarean section, see this summary from our Health Resource Center.