Women with a prior cesarean section, who undergo labor for their second child, are at increased risk of a rupture of the uterus, compared with women who elect another cesarean section birth. This finding by a University of Washington team of researchers appears in the July 5 issue of The New England Journal of Medicine.
The study involved analyzing the records of 20,095 women who had their first child delivered by cesarean section and who delivered a second child either by cesarean or following labor. These records were from 1987 through 1996 and came from civilian hospitals in Washington State. The research was funded by the National Institute of Nursing Research, National Institutes of Health, and by the Agency for Healthcare Research and Quality.
The rate of uterine rupture for repeat cesarean deliveries without labor for women having a previous C-section was 1.6 per 1,000 women. Uterine rupture was highest where prostaglandin, a naturally-occurring substance in the body administered to induce labor, was used for the second birth -- 24.5 per 1,000 women. For women whose labor was induced without prostaglandin, the rate was 7.7 per 1,000 women. And for those with spontaneous onset of labor, the rate was 5.2 per 1,000 women. As these data indicate, uterine rupture is not that common, but it may have serious consequences that include hysterectomy, urologic injury, or need for a blood transfusion for the mother, and neurologic impairment in the infant.
"Undergoing cesarean delivery comes with its own risks," said Dr. Mona Lydon-Rochelle, principal investigator of the study. "Now we have indications that second births following labor by women with an earlier C-section also include higher risks of uterine rupture. What this research shows is that having that first C-section adds to the complexity of assessing the risk/benefit ratio of procedures to use for the births to follow. Another factor brought to light by the study," she added, "is the use of prostaglandins to induce labor, which produces the greatest risk of uterine rupture when there have been prior C-sections."
Dr. Patricia A. Grady, Director of the NINR, added that "further research is needed to increase knowledge about how to reduce the risk of various birth procedures. Since many women with prior C-sections have been electing to try labor for their second pregnancy, it is important that before this decision is reached, they assess the relative risks and discuss them with their healthcare providers."
"These data also raise the question of the risk of induction of labor for women with a prior C-section," stated Dr. Nancy Woods, Dean of the University of Washington's School of Nursing and former head of their Center for Women's Health Research, where the study originated.
The research team included Dr. Mona Lydon-Rochelle, principal investigator and senior research fellow in the Department of Family and Child Nursing in the School of Nursing, Dr. Victoria L. Holt, associate professor in the Department of Epidemiology in the School of Public health and Community Medicine; Dr. Thomas R. Easterling, assistant professor of obstetrics and gynecology of the School of Medicine; and Dr. Diane P. Martin, Professor in the Department of Health Services in the School of Public Health and Community Medicine, all at the University of Washington.