Boldly into the breech controversy.

Addressing a long-simmering controversy, a large new study has shown that in pregnancies where the baby has positioned itself to emerge feet or buttocks first, the delivery safest for mother and child is a planned cesarean section, or C-section, rather than a vaginal birth.

In 3 to 4 percent of all pregnancies, the babies end up in the so-called breech position. Some physicians have favored vaginal delivery for such babies because, like any major surgery, C-sections may lead to blood loss, infection, and other complications in the mother. Other doctors have preferred C-sections because infants in the breech position tend to get stuck in the birth canal. Such infants may have trouble getting oxygen and may be scraped or injured during delivery. Often, the doctor must call for an emergency C-section in the midst of the birth.

At 121 centers in 26 countries, researchers followed 2,083 women carrying infants in the breech position. Each woman was randomly assigned to give birth either vaginally or via C-section. They were then observed for 6 weeks after delivery.

More than 90 percent of the women assigned to have a C-section delivered their babies that way. About 57 percent of those assigned to give birth vaginally did so; the rest had emergency cesareans.

The type of delivery didn't influence the incidence of maternal death or serious illness. However, 5 percent of the breech-position infants born vaginally died during or soon after birth, compared with just 1.6 percent of babies born via a C-section, Mary E. Hannah of the University of Toronto reports in the Oct. 21 LANCET. This difference convinced her to end the study early.

"The risk of a baby dying with planned vaginal birth was much higher than we had anticipated," she says.

The trial "was designed to reduce the uncertainty, and it certainly did," Judith Lumley of La Trobe University in Melbourne, Australia, said in an editorial accompanying the report. "The next step is rapid dissemination of the current findings to pregnant women, their families, and all clinicians involved in maternity care."