Factors Predicting Successful Vaginal Delivery After Cesarean in Low-Risk Women Identified in UB Study

BUFFALO, N.Y. -- Physicians dispensed with the "Once a cesarean, always a cesarean" approach to childbirth in low-risk women more than 20 years ago, in an effort to curb the rising cesarean rate. However, rates of vaginal birth after cesarean (VBAC) began to decline in the mid 1990s.

To shed light on this development, epidemiologists at the University at Buffalo assessed specific characteristics that were associated with both attempt and success of VBAC in women who were low-risk candidates for this type of delivery in Central New York.

The results were presented today (June 15) at the Society for Pediatric and Perinatal Epidemiological Research annual meeting in Salt Lake City.

Their findings showed that, compared to mothers who chose a repeat cesarean, women who attempted a vaginal delivery were more likely to be younger and have more education. They had delivered more children, tended to be slimmer before their pregnancy, lived in or near a city, and had larger babies and longer pregnancies.

In addition, researchers found that minority women were more likely than Caucasian women to attempt vaginal delivery after a previous cesarean section, but were less successful in their attempts.

Mothers who were successful delivering their babies vaginally had much in common with those who were willing to try, results showed: they were likely to be more educated, multiparous and have a lower body mass index before pregnancy.

Other factors associated with success were: delivery in a hospital with a neonatal intensive care unit, lower-birth-weight baby, use of an epidural anesthetic during labor and spontaneous versus induced labor, results showed.

"Our data will help physicians identify mothers who are more likely to attempt labor and have a successful vaginal birth," said Jennifer Reschke, lead author on the study from the Department of Social

and Preventive Medicine, UB School of Public Health and Health Professions.

"We hope this information will help to explain some of the factors associated with the decline in VBAC rates in the past few years," she said.

Cesarean sections remain the most frequently performed major surgery in the United States. Previous research has shown that cesarean sections may be more likely to result in complications, such as longer hospital stays and higher average blood loss during labor, and involve a longer recovery period at home than a vaginal birth.

The peak year in the U.S. for successful vaginal births after cesarean section was 1996, when it reached 28.3 percent of women with a previous cesarean. The rates have declined since then, said Reschke, primarily due to fewer women electing to attempt labor.

The current study was based on a review of 6,277 electronic birth certificates from the Finger Lakes Regional Perinatal Data System, which collects data from 17 hospitals in nine New York counties. The study population was restricted to women who did not have multiple births, gave birth in a hospital, were at least 37 weeks pregnant, had a previous cesarean section and had no medical conditions that would rule out a labor attempt.

Additional researchers on the study were Jean Wactawski-Wende, Ph.D., and Jacek Dmochowski, Ph.D., from the UB Department of Social and Preventive Medicine, UB School of Public Health and Health Professions; John Yeh, M.D., and James A. Shelton, from the UB Department of Gynecology and Obstetrics, and Ann Dozier, Ph.D., and Joseph Duckett from the University of Rochester.

The New York State Perinatal Data System is funded by a grant from the New York State Department of Health.

The University at Buffalo is a premier research-intensive public university, the largest and most comprehensive campus in the State University of New York. UB's more than 27,000 students pursue their academic interests through more than 300 undergraduate, graduate and professional degree programs.