By Kathleen Doheny
FRIDAY, Aug. 7 (HealthDay News) -- Babies poised to enter the world feet first can pose serious complications for themselves and their moms.
Among single-baby pregnancies, just 3 percent to 5 percent are known as "breech presentations," with the baby's bottom, rather than head, positioned closest to the birth canal.
But though the numbers are small, experts say the risks can be big. Because of this, knowing about a breech presentation ahead of time can help the parents-to-be and their doctor decide what to do -- whether to try to rotate the baby in the womb or prepare for a Cesarean delivery.
"The trend is not to deliver breech vaginally," said Dr. Joshua Copel, a professor of obstetrics, gynecology and reproductive sciences at the Yale University School of Medicine. "Most breech [babies] get delivered by C-section."
With breech presentation, vaginal birth can be far more difficult. According to the American College of Obstetricians and Gynecologists, it can be difficult to guide the baby's head out of the mother's body last because the baby's body might not have stretched the cervix sufficiently. And a prolapsed cord -- when the umbilical cord slips into the birth canal before the baby, stopping the flow of blood to the baby -- is another increased risk in vaginal deliveries of breech babies.
The standard way to detect breech -- by feeling a woman's abdomen -- isn't foolproof. A BMJ study, in fact, reported that 30 percent of breech presentations were missed when this method was used. In some cases, that has prompted the addition of an ultrasound examination if a breech presentation is suspected.
"If I am uncertain about a baby's position by 33 or 34 weeks, I recommend an ultrasound," said Susan Moray, a certified professional midwife in Portland, Ore., and a spokeswoman for the Midwives Alliance of North America. "I think it's used more than in the past."
In fact, it can be overused, Moray said, citing a woman she knew who had 11 ultrasounds during her pregnancy.
But Copel and Moray agreed that ultrasound can be valuable in detecting breech babies.
Once the ultrasound confirms a breech presentation, they explained, a technique called external cephalic version can be done. This involves external manipulation to turn the baby in the womb to a head-first position.
It's typically done at week 35 or 36. (A full-term pregnancy is about 40 weeks.) "Seventy percent of the time, it works," Copel said.
The procedure typically is not done earlier, even if a baby's breech presentation has been confirmed. "I don't worry about breech presentation until the woman is getting close to 34 weeks," Moray said. "Babies often flip around," and the problem could correct itself, she explained.
Some evidence exists that breech presentations run in families or have a genetic link, according to another BMJ study, published last year. If one or both parents were born breech, it found, their children were twice as likely to be born that way, too.
And Moray said that she might pick up that information in her standard questioning of medical history. But Copel doesn't believe that such information is of much practical use.
Even with a woman who had no family history of breech presentations, he said, he still has to keep in mind the possibility that the baby could be feet-down in the womb.
If a baby is still feet-first near the due date, a C-section will probably be recommended, Copel said. But some women may be committed to a vaginal birth and ask if that's possible.
It could be, according to the American College of Obstetricians and Gynecologists, which issued a committee opinion on breech babies about three years ago. But the opinion stresses that great caution must be exercised if a breech baby is to be delivered vaginally and advises doctors to warn prospective parents of potential risks and have them sign a consent form saying that they're aware of the risks.
In a breech baby, according to the American Academy of Family Physicians, the infant's hip socket and thighbone are more likely to become separated during a vaginal delivery, and compression of the umbilical cord is also more likely, which can lead to brain damage from a lack of oxygen.
But Cesarean delivery is not risk-free either. Greater chances for bleeding and infection as well as longer hospital stays have been found for women who deliver by C-section.