Vaginal Births After C-Sections Decline

But mortality rates for mothers, babies didn't drop, study finds

TUESDAY, May 30, 2006 (HealthDay News) -- The number of women who gave birth vaginally after a Caesarean delivery has dropped in recent years, but without the expected reduction in infant and maternal death rates, a new study has found.

Women who deliver vaginally after having a previous C-section face small but real health risks, such as uterine rupture. So, as the number of vaginal births after Caesarean sections (VBACS) declined, it would have seemed that infant and maternal death rates would have fallen, too, said study leader Dr. John Zweifler, chief of the University of California, San Francisco-Fresno Family and Community Medicine Department.

Zweifler and his colleagues examined birth data in California from 1996 through 2002, before and after a 1999 guideline to reduce vaginal births after Caesarean sections was adopted. The guideline, issued by the American College of Obstetricians and Gynecologists, requires a physician to be immediately available in the hospital to perform emergency care for a woman attempting vaginal birth after a prior Caesarean section, in case of complications such as uterine rupture. Because that's not always possible, especially for smaller hospitals, the VBAC rate was expected to decline.

The researchers found 386,232 California women who had given birth by C-section. About 75,000 attempted a subsequent vaginal delivery, while the other 311,000 had a repeat C-section. Of those who attempted a vaginal birth after a C-section, more than 61,000 were successful.

The study authors found that attempted vaginal births after a C-section dropped from 24 percent before the guidelines to 13.5 percent after the guidelines. Women who gave birth to low birth weight babies -- less than 1,500 grams, or 3.3 pounds -- had higher newborn death rates with VBAC than a C-section, Zweifler said. But women giving birth to infants of normal weight -- at or above 3.3 pounds -- had similar newborn and mother mortality rates, regardless of whether it was vaginal birth after a C-section or a repeat C-section, the researchers found.

For instance, for newborns weighing 5.5 pounds to less than 8.8 pounds, "there were 0.3 deaths per 10,000 live births before the guidelines [with attempted VBAC], Zweifler said. "After the guidelines, there were 0.4" per 10,000 live births.

For women undergoing repeat C-sections for children of normal weight, there were 0.4 deaths per 10,000 live births before the guidelines, and 0.3 deaths afterward, the researchers reported.

Similarly, maternal death rates per 100,000 live births for attempted VBAC deliveries were pretty much the same for both periods -- two for the years 1996 to 1999, and 8.5 from 2000 to 2002. For repeat C-sections, the maternal death rates per 100,000 births were 8.7 from 1996 to 1999, and 11.9 from 2000 to 2002.

The study findings appear in the May-June issue of the Annals of Family Medicine.

The 1999 guidelines were issued due to safety concerns and medical and legal considerations, the researchers said.

In the United States, babies born by C-section increased from 4.5 percent in 1965 to 26.1 percent in 2002, with nearly 40 percent of the births repeat C-sections. Vaginal births after a C-section increased from 1 percent in 1974 to 27.4 percent in 1997, then back down to 12 percent in 2002, the researchers said.

In an accompanying essay, Dr. Lawrence Leeman, a physician who specializes in family medicine, obstetrics and gynecology at the University of New Mexico, said preserving a woman's childbirth options means preserving her right to a vaginal birth after a Caesarean section, as well as a C-section.

Dr. Richard Frieder, an obstetrician-gynecologist at Santa Monica-UCLA Medical Center and a clinical instructor of obstetrics and gynecology at the David Geffen School of Medicine at the University of California, Los Angeles, said the new study has a major flaw. "It doesn't address maternal or fetal complications," he said. "The study took birth certificates, and all they did was add up numbers of who lived and who died in terms of infant mortality and maternal mortality."

"The main complication of VBACs is not death but morbidity, such as blood transfusions, hysterectomy, infection, heart attack, stroke, kidney failure, the baby having low Apgar scores or brain hemorrhage," Frieder said. "All they are talking about is how many people lived or died. But they didn't measure complications. If they had looked at complication rates, there would have been a huge difference favoring C-section."

Complications weren't considered, Zweifler said, because the only information the researchers had access to was birth certificate data, which don't list complications.

More information

To learn more about C-sections and vaginal births after a C-section, visit the

SOURCES: Richard Frieder, M.D., obstetrician-gynecologist, Santa Monica-UCLA Medical Center, Santa Monica, Calif., and clinical instructor, obstetrics and gynecology, David Geffen School of Medicine, University of California, Los Angeles; John Zweifler, M.D., M.P.H., chief, University of California, San Francisco-Fresno Family and Community Medicine Department, and medical consultant, State of California Office of the Patient Advocate, Sacramento; Lawrence M. Leeman, M.D., M.P.H., researcher, department of Family and Community Medicine, University of New Mexico, Albuquerque; May-June 2006 Annals of Family Medicine
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