Uterine rupture is an uncommon, but serious, obstetrical condition that may result in hysterectomy, urologic injury or a need for blood transfusion for the mother, and neurologic impairment in the infant.
The study was done by Dr. Mona Lydon-Rochelle, senior research fellow in the Department of Family and Child Nursing in the School of Nursing and her colleagues 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.
Researchers used data from the delivery records of 20,095 mothers who delivered a single live infant in Washington state from 1987 through 1996 and also delivered a second single infant during the same time period. They found that a total of 91 women had a uterine rupture during the second birth. Women with a spontaneous onset of labor were 3.3 times more likely to have a uterine rupture than women who had a repeat Caesarean delivery without labor.
Women with non-prostaglandin induction of labor were nearly five times more likely to have a uterine rupture and women with prostaglandin induction were 15 times more likely to have a uterine rupture than women who had repeat Caesarean deliveries without labor.
"These associations are most likely real, given the magnitude of reported risk," said Lydon-Rochelle, the study's lead author. "Although prior studies are not in complete agreement, it seems clear that whatever increased risk might be present in women whose labor is induced is considerably greater than what is present in women with repeat Caesarean delivery."
Lydon-Rochelle said that since about 60 per cent of women with a prior Caesarean delivery who become pregnant again attempt a trial of labor, concern persists that a trial of labor increases the risk of uterine rupture.
"It is important for women who have had a Caesarean in the past to know that attempting a vaginal delivery increases the chances of uterine rupture," said Holt, the study's co-principal investigator. "The decision to make such an attempt should be made with the knowledge of the increased chance of other problems that may occur in a repeat Caesarean delivery."
"Our work does not suggest that the practice of vaginal birth after Caesarean delivery should be abandoned," Easterling said. "However, these births should be performed in a medical environment where complications can be managed rapidly and effectively. Given the potential risk to the mother and baby, the decision to attempt a vaginal birth after a Caesarean birth should be made between the pregnant woman and her health practitioner."
The study data was derived by assessing birth certificate and hospital discharge data in the Washington State Birth Events Database. In prior studies, information about trials of labor was based on physician survey or hospital discharge data alone. The UW study's approach increased the accuracy and completeness of the data on obstetrical diagnosis and procedures.
The research was funded in part by grants from the Agency for Healthcare Research and Quality and the National Institute of Nursing Research in the National Institutes of Health.