Women who have delivered a baby by Caesarean section face a small risk of complications that could endanger the baby if they attempt a vaginal delivery the next time, a large new study has found.
The findings, the most definitive data so far on the safety of trying to deliver vaginally after a Caesarean, immediately rekindled debate on the controversial issue.
Proponents of attempting a vaginal delivery said the findings should give doctors and women confidence that the risk is relatively low and that most women and their babies will not experience major problems. But other experts said the findings underscore the dangers of attempting vaginal birth after a Caesarean and provide new evidence that women should not be encouraged to do so.
Experts on both sides, however, said the findings provide necessary information for women to make an informed decision on whether they are willing to accept the risk.
"Some people will look at the risk and say, 'That's a really low number. I'm willing to accept the risk.' Others will say, 'There's no way,' " said Michael F. Greene, director of maternal-fetal medicine at Massachusetts General Hospital in Boston, who wrote an editorial accompanying the study in this week's issue of the New England Journal of Medicine. "That's the value of this kind of study. Risk is in the eye of the beholder."
A Caesarean section is a surgical procedure that is performed to deliver a baby, usually when the mother or child is experiencing a complication that puts one or both of them at risk. For years, some doctors and advocates of vaginal birth have encouraged women who had one Caesarean to try to avoid the cost, added recovery time and possible surgical complications by attempting to deliver their next child vaginally.
But the rate at which women had been attempting a vaginal birth after Caesarean, known as VBAC, began falling in the late 1990s following reports of life-threatening complications, most notably ruptures of the uterus. In recent years, many smaller hospitals nationwide have stopped performing the procedure because of the costs of malpractice insurance and having the necessary doctors available in case of an emergency. That has caused frustration among some women who wanted to attempt a vaginal delivery but were unable to find a doctor or hospital willing to offer that option.
The new study was organized and funded by the National Institute of Child Health and Human Development to provide better data on the risks associated with VBAC. Researchers compared 17,898 women who attempted a vaginal birth and 15,801 who had another Caesarean at 19 academic medical centers nationwide.
Of the women who tried to deliver vaginally, 124 -- less than 1 percent -- experienced a ruptured uterus, and seven babies suffered brain damage from a lack of oxygen because of labor complications, including two who died. Women who attempted a vaginal birth were also more likely to develop an infection of the uterine lining. No serious problems occurred among women who had repeat Caesareans.
Overall, among the women who attempted a vaginal birth, the risk of brain injury or death for the baby from a uterine rupture was about 1 in 2,000 deliveries, the researchers reported.
Mark B. Landon, a professor and vice chairman in the department of obstetrics and gynecology at Ohio State University who led the study, said the findings show that VBAC generally can be safe.
"At this level of risk, I think clearly many women will still opt for attempting a vaginal birth after a Caesarean," he said. "I think many women have been dissuaded from VBAC because of inadequate counseling concerning the magnitude of the risk. Hopefully this will help women make a more informed decision."
Bruce L. Flamm, a professor of obstetrics and gynecology at the University of California at Irvine, agreed.
"The bottom line is that this study shows that VBAC is safe in an appropriate setting," he said. "My feeling is that it should be a patient's choice."
But other experts said the findings probably would contribute to continuing the trend of more women opting for repeat Caesareans.
"I think it will keep going in the direction it is," said W. Benson Harer Jr., medical director of the Riverside County Regional Medical Center in Moreno Valley, Calif., and a past president of the American College of Obstetricians and Gynecologists. "The risk they found in this study is probably as good as you could hope."
