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
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