TUESDAY, Dec. 14, 2004 (HealthDayNews) -- Women who attempt to deliver their babies vaginally after a Caesarean section face some health threats to themselves and their babies, although those risks are small.
A new study has confirmed that the rate of a uterine rupture, one of the most serious consequences of a C-section, is between 0.5 and 1 percent.
"With probably the best available data to date on this subject from the United States, it appears that the absolute risks associated with undergoing a trial of labor after a previous Caesarean section are fairly small," said Dr. Mark B. Landon, lead author of the study, which appears in the Dec. 16 issue of the New England Journal of Medicine.
"Trial of labor" simply means that a woman who has had a previous C-section is now attempting to deliver vaginally, regardless of whether she succeeds.
The findings, the authors state, should be used to counsel women who are about to have babies. "It's very much a personal decision, but the important fact is that women be informed of the levels of risk involved and not receive a biased approach to counseling, or one in which that there is superficial information provided," said Landon, who is vice chairman of the department of obstetrics and gynecology at Ohio State University College of Medicine and Public Health.
At the same time, risks associated with C-section, which were generally not addressed in this study, also need to be taken into account. "There are other maternal risks to C-section beyond discomfort issues," pointed out Dr. Andrei Rebarber, an associate professor of obstetrics and gynecology and maternal-fetal medicine at New York University School of Medicine. These include blood clotting, chronic pelvic pain, and even infertility.
The issue of C-sections and of repeat C-sections has been a controversial one.
In 1970, C-sections represented 5 percent of all deliveries but, by 2002, had surged to 26 percent of all deliveries.
Vaginal deliveries after C-section went from 3 percent of all deliveries in 1981 to 31 percent in 1998, then dropped back down to 12.7 percent in 2002, partly because of concerns about uterine rupture and other health risks, according to the authors.
U.S. health agencies have been trying to reduce the rate of surgical deliveries, both overall and after a previous C-section.
To clarify the risks involved in the procedure, Landon and his colleagues conducted a four-year prospective study of more than 33,000 women at 19 academic medical centers. During the time period (1999 to 2002), vaginal delivery was attempted by 17,898 women, while 15,801 underwent an elective repeated C-section. Roughly 73 percent of those attempting trial by labor were successful, while 27 percent failed the trial and required a repeat C-section.
Of the women who underwent trial of labor, 124 (0.7 percent) had uterine rupture, while 12 infants had brain damage from lack of oxygen, seven of them following uterine rupture; two babies died. This translates into an absolute risk of 0.46 per 1,000 women. This type of data had been missing from previous studies, Landon said.
No infants experienced this complication in the C-section group.
The rate of endometritis, an inflammation of the lining of the uterus, was higher in the trial of labor group (2.9 percent vs. 1.8 percent) as was the rate of blood transfusion (1.7 vs. 1 percent).
The frequency of hysterectomy and maternal death was small, and similar in both groups.
Overall, concluded the authors, there would need to be 588 elective repeated C-section deliveries to prevent one poor outcome.
Women undertaking trial of labor need to consider several factors, including the risk of a serious event for her or her newborn. Although most uterine ruptures can be repaired, some require a hysterectomy. More importantly, however, uterine rupture can cause death or brain damage in the fetus.
"For women undergoing trial of labor, the overall risk of one of these serious adverse outcomes at term is one in 2,000 trials of labor," Landon said. "For many women, that level of risk is clearly acceptable, with the benefit being a potential vaginal birth with shorter recovery, less hospitalization, and the satisfaction that goes with vaginal delivery itself. For other women, any level of potentially preventable fetal risk is unacceptable."
More information
Go to Childbirth.org to learn about C-sections.
