Current studies suggest that opinion leaders and national guidelines have the most significant effects on rates of vaginal birth after C-section, or VBAC. But studies are inconclusive about whether legal factors, doctor and physician characteristics and insurance type affect VBAC rates, say Dale Kraemer, Ph.D., and colleagues at Oregon Health and Science University.
"Of the aspects of the health care system considered in this report, the best evidence for impacting rates of VBAC is associated with guidelines," Kraemer says.
After a significant increase in Caesarean rates in the United States between 1970 and 1980, participants at a national conference in 1981 recommended letting women with prior Caesareans try labor and vaginal delivery.
Rate of VBAC increased steadily from 1989 to 1996, but have decreased every year after that.
Kraemer and colleagues systematically reviewed studies relating various factors to VBAC rates from 1980 to 2002. They found no good evidence that litigation or legislative mandates influenced VBAC rates, but acknowledge that few studies of legal influences exist.
"No study addressed the impact of litigation or malpractice insurance rates on obstetric providers' decisions on mode of delivery in women with previous Caesarean," Kraemer says.
The researchers did not uncover any good evidence showing that individual physician delivery preference or a patient's insurance type affect VBAC rates.
Kraemer and colleagues did find some studies suggesting that the type of hospital could influence VBAC rates. However, the studies varied in their definition of hospital types, making it difficult to determine their exact influence.
They conclude that more research is necessary to know how outside factors are affecting VBAC and repeat Caesarean rates.
"Given the quality of current evidence in the literature, policy recommendations are not feasible at this time," Kraemer says.
The study was supported by the Agency for Healthcare Research and Quality.
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BY BECKY HAM, SCIENCE WRITER
HEALTH BEHAVIOR NEWS SERVICE