Women who attempt vaginal childbirth after having several babies by cesarean section may not have a greater risk of complications than women who’ve had only one prior C-section, a new study suggests.

At one time, doctors believed that once a woman had a C-section, she would have to have one for all subsequent pregnancies - mainly out of concern that the scar on the uterus could rupture during vaginal childbirth.

That thinking has changed, and vaginal delivery is now considered a safe option for many women who have had a past C-section. Because C-sections also carry risks and downsides - such as blood loss or infection from the procedure, and a longer hospital stay and recovery time - many women may prefer a try at labor.

Still, the American College of Obstetrics and Gynecology (ACOG) does not currently recommend vaginal delivery for women who have had three or more C-sections, as their risk of uterine rupture has generally been thought to be higher.

In the new study, however, researchers found that women with at least three prior C-sections showed no increased risk of uterine rupture during vaginal delivery.

In fact, none of the 89 women who opted to try vaginal childbirth had the complication, according to findings published in the British obstetrics journal BJOG.

Based on past research, the expected rate of uterine rupture among women with one prior C-section would be less than 1 percent; a large 2004 study of U.S. women, for example, found a rate of 0.7 percent.

These latest findings suggest it would be “reasonable to reconsider” the current ACOG recommendations for women with three or more prior C-sections, according to lead researcher Dr. Alison G. Cahill of Washington University School of Medicine in St. Louis.

In an interview, she noted that next month, the National Institutes of Health is holding a consensus conference on the overall issue of vaginal birth after cesarean. According to the NIH, the conference will look at the scientific evidence on a number of questions - including the short- and long-term risks and benefits of vaginal delivery versus repeat C-section; an independent panel will then develop a consensus statement on those issues.

For now, Cahill said, it is important for women with a history of three or more C-sections to be aware of the current ACOG recommendation. But, she added, they can also talk with their doctors about the possibility of vaginal birth as an option, as “recommendations can change as new science emerges.”

For their study, Cahill and her colleagues reviewed the records of 25,000 women at 17 U.S. hospitals who gave birth after having at least one prior C-section. The group included 860 women with at least three prior C-sections, 89 of whom attempted a vaginal delivery; the remaining 771 elected to have a repeat C-section.

There were no cases of uterine rupture in either group, the researchers found.

The 89 women who chose to try labor also had no instances of bladder or bowel injury, or lacerations of the uterine artery - the other main complications the researchers assessed. That compared with just over 2 percent of the women who had a repeat C-section - though that difference, the researchers say, is not significant in statistical terms.

When it came to successful delivery - meaning the doctor did not have to switch to a C-section during labor - the chances were similar regardless of the number of prior C-sections.

Just over 13,600 women with one or two prior C-sections elected to try vaginal delivery, with a success rate of about 75 percent. That rate was 80 percent among women with a history of three or more C-sections.

Last Updated: 2010-02-18 13:00:21 -0400 (Reuters Health)

Cahill pointed out that all of the women in the study had had C-sections done with what is called a low transverse incision - a horizontal cut across the lowest part of the uterus. These types of incisions have a lower risk of rupture compared with the “classical” high vertical incision, an up-and-down incision made higher on the uterus.

Another factor to consider in the decision to try vaginal delivery after cesarean, according to Cahill, is whether a woman has ever had a previous vaginal birth. Previous vaginal deliveries increase the chances of success with a post-cesarean attempt at vaginal birth.

SOURCE: BJOG, online February 3, 2010.