NEW YORK - The proportion of twins who are delivered by cesarean section in the US has shot up "dramatically" since the mid-1990s, according to a new study.
While sometimes the babies' position or other delivery complications make a C-section necessary, California researchers reported that the largest relative increase in the practice was seen in healthy moms and babies who were well positioned to be delivered vaginally.
"There seems to be a very liberal approach to cesarean section with twins that has evolved over the last decade," said Dr. Mark Landon, the head of obstetrics and gynecology at Ohio State University in Columbus.
"The numbers are pretty dramatic in terms of the fact that three-quarters of twins undergo cesarean section now," Landon, who wasn't involved in the new study, told Reuters Health.
The 75 per cent C-section rate in 2008, the most recent year covered in the study, is up from just over 53 per cent in 1995.
That adds up to a five per cent increase each year in the proportion of twins born via C-section nationwide.
And the trend couldn't be explained by an increase in complications, sicker moms or more "breech" babies positioned to be born feet-first.
Even in healthy women with the lowest risk of a delivery complication, and babies that were aligned head-first, the C-section rate increased from one-third of births at the beginning of the study period to more than half at the end.
In those cases, "there is really no evidence that cesarean delivery confers a benefit to either the mother or the infant, Landon said.
The findings, published in Obstetrics & Gynecology, are in line with other recent research suggesting that the C-section rate for all babies -- not just twins -- has been climbing. (See Reuters Health story of December 23, 2010).
Now, C-section deliveries account for about one-third of all births in the US
Researchers have been unsure why that's the case. Some have suggested that obstetricians might be giving up on vaginal deliveries and switching to C-sections earlier in labor than they used to, or that more women are requesting C-sections so they can have greater control over when their babies are born.
But having a C-section raises a mother's risk of bleeding and infection, as well as bowel and bladder injuries. The procedures also mean longer hospital stays and higher price tags.
"We know that sometimes they're appropriate and going to be beneficial... but in some instances there's no clear reason for them and it can potentially cause problems for the mother or baby," said Dr. Henry Lee from the University of California, San Francisco, who worked on the study.
And the increase in C-sections for twins, he told Reuters Health, "is not really explained by any kind of medical reason."
Lee said there needs to be more research on when C-sections are beneficial in dealing with twins, but his study suggests they're being done too frequently.
"It's a priority in our country now to decrease the cesarean rate overall," he concluded.