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Study cites birth risks

Vaginal delivery after C-section may be harmful

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More than a decade after doctors declared it safe for women to give birth vaginally after having had a Caesarean section, a new study has found that vaginal delivery is riskier to both mother and child than a second surgical delivery, especially if hormones are used to induce labor.

The study, published Thursday in The New England Journal of Medicine, found that women undergoing vaginal birth after Caesarean, or VBAC, were three times as likely as those who deliver surgically a second time to suffer a ruptured uterus, an extremely uncommon but dangerous complication that can kill the mother, her baby or both.

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"We used to believe that vaginal birth after Caesarean was pretty much risk-free," said one of the study's authors, Dr. Thomas Easterling, an associate professor of obstetrics and gynecology at the University of Washington in Seattle. "Now we know that it's not. There are risks. They are small but can be catastrophic."

Women should carefully discuss those risks with their health-care providers, Easterling and other experts said.

Uterine rupture occurred in just 91 of more than 20,000 women whose birth records were examined for the study. But beyond the increased risk of such rupture in VBAC women as a whole, the researchers found the rate to be 15 times as high among women given prostaglandins, hormones that help ready the cervix for labor, as among those who had second Caesarean sections.

Among women whose labor was induced with other hormones, the rate was five times that of the second-Caesarean women.

The researchers said the study strongly suggested that obstetricians should avoid the use of drugs to induce labor in women who have had previous Caesareans, a precaution some obstetricians say they have already adopted.

"Let her go into spontaneous labor," said one of those obstetricians, Dr. Roger K. Freeman, who practices in Long Beach, Calif., and who headed a panel that studied Caesarean section for the American College of Obstetricians and Gynecologists. "Don't induce her. And if you are in a situation where you would consider induction, just do a repeat C-section."

Freeman said the study offered "good data" to support changes he and other doctors had already made in their practices.

For decades, the medical mantra about childbirth was "once a Caesarean, always a Caesarean." The prevailing thinking was that scar tissue from the surgical incision rendered the uterine wall too weak to withstand the strain of powerful contractions during labor. Should the uterus rupture, the mother may bleed uncontrollably and the baby may lose oxygen; to save both, an emergency Caesarean section is necessary within 15 to 20 minutes, experts say.

In the mid-1980s, however, VBAC (pronounced VEE-back) came into vogue, for several reasons. By that time, doctors had abandoned the practice of making vertical incisions in the uterus in favor of low transverse cuts (many women call them bikini scars), which were believed to heal better. Subsequent studies found that the risk of uterine rupture with vaginal birth after Caesarean was small, about 0.5 percent.

At the same time, there was growing concern that too many women in the United States were undergoing Caesareans unnecessarily, exposing them to risk of surgical complications. And some health insurers, concerned about rising costs, began insisting that women with previous Caesareans try natural childbirth.

"Over time, perceptions changed," said Dr. Michael F. Greene, an obstetrician at Massachusetts General Hospital, where he is director of maternal-fetal medicine. "The catastrophes are few and far enough between that if you don't look too hard, you might not notice them."

Greene, an associate editor of The New England Journal of Medicine, said the Washington study brought those catastrophes into sharp relief and was the first to compare the risks of vaginal birth with those of a second surgical delivery "in a statistically significant, scientifically valid way."

The study, Greene noted, found that the incidence of infant death was 10 times as high among the women who suffered uterine rupture as among those who did not. The study did not prove a cause-and-effect relationship between the ruptures and those deaths, but in a strongly worded editorial accompanying the study, Greene wrote that in light of the findings, if a patient who has had a Caesarean asks him what is safest for her next baby, "my unequivocal answer is elective repeated Caesarean section."

Already, medical practice is beginning to shift in that direction, partly because smaller, less rigorous studies have hinted at findings similar to those at Washington. According to the National Center for Health Statistics, the rate of vaginal births after a previous Caesarean section, which increased by 50 percent from 1989 to 1996, has now dropped: in 1999, 23.4 percent of women who previously delivered surgically gave birth vaginally, down from 26.3 percent three years earlier.

At the same time, the center says, the rate of Caesarean delivery in the United States has steadily increased since 1996, when 20.7 percent of American children were delivered by Caesarean section; by 1999, the most recent year for which figures are available, the figure was 22 percent.