It has long been recognized that many countries have high C-section rates. In the U.S., C-sections now account for one-third of all deliveries -- an all-time high.
The reasons are various. The rising rate of multiple births has played a role, since twins or "higher-order" multiples often need to be delivered by C-section.
But experts generally agree that rates in the U.S. and many other countries are too high, since it's unlikely that the rapid increase since the 1990s is due exclusively to medical need.
There is no agreement on what the "correct" C-section rate is. But the World Health Organization has suggested that rates above 15 percent are probably too high.
In the new study, researchers found that 69 countries worldwide top that 15 percent rate. On the other end of the spectrum, 54 countries had C-section rates lower than 10 percent -- which may be below what is medically needed.
Then the researchers calculated the costs. In countries with high C-section rates, they estimate, getting the figure down to 15 percent would save $2.3 billion globally each year. In countries with low rates, the cost of bringing them up to 10 percent would be $432 million, the researchers report in the American Journal of Obstetrics and Gynecology.
There are other reasons to limit C-sections to only those cases where it's the best course for the mother's or baby's health. Although the procedure is generally safe, it is still major abdominal surgery with inherent risks, like infection or too much blood loss.
C-sections also boost the odds of certain problems with later pregnancies, including abnormalities in the placenta that can lead to severe bleeding during labor.