No one knows exactly how many C-sections are purely elective. It's an intense controversy: Some estimates suggest there could be tens of thousands annually, and critics say many of those women were pressured into surgery or didn't know the risks.
Amid the uncertainty, the National Institutes of Health opened a three-day meeting Monday to determine just how much is known about the risks and benefits of a preplanned Caesarean - and how to ensure that mothers-to-be get all the facts.
''We all have noticed that women are asking for Caesareans more often. I don't think they always have the best information in making that decision,'' said Cathy Spong, pregnancy chief at NIH's National Institute of Child Health and Human Development.
A Caesarean can be life- or health-saving for many mothers and babies. Fetal distress, twins or more, or diseases that make labor risky for the mother are important reasons to have one.
At the same time, it is major abdominal surgery that poses some rare but serious, and occasionally life-threatening, side effects, such as hemorrhage, infection and blood clots. In addition, a prior C-section increases the risk of complications in future pregnancies, such as stillbirth or problems with the placenta, Spong says.
So what's the lure if it's not medically necessary?
Convenience plays a role for busy women. Maybe mothers need to schedule delivery so relatives can visit to take care of older children, or they live far from a hospital and worry about arriving in time. Or they fear something will go wrong and they'll wind up with an emergency Caesarean, considered far riskier than a planned one, especially if performed by a tired physician.
In 2004, the latest data available, 29.1 percent of the nation's 4 million births were by Caesarean. That's the highest rate ever recorded, a 40 percent rise since 1996.