By Genevra Pittman
NEW YORK (Reuters Health) May 08 - Very premature babies have fewer breathing problems when they're born through vaginal delivery compared to cesarean section, a new study of more than 20,000 newborns suggests.
Regardless of why a C-section was performed, vaginal delivery tended to be safer, the researchers found.
"My suspicion is that the labor process, the contractions, that natural squeezing probably does something to clear out the lungs so that when babies are born they have a better breathing status," said Dr. Erika Werner, who led the new study at Johns Hopkins School of Medicine in Baltimore.
"If a vaginal delivery is safe, it's something that should be attempted," she said.
There are certain circumstances when a C-section is clearly required, Dr. Werner said. However, she added, there hasn't been much data on whether C-section or vaginal delivery is the generally safer method for premature babies when an emergency C-section isn't called for.
Her team's data come from birth certificates and hospital discharge records for 20,231 babies born in New York between 1995 and 2003. All were born between 24 and 34 weeks gestation.
Just over two-thirds of the babies were born vaginally.
After taking into account the mother's age, race and underlying medical conditions, Dr. Werner and her colleagues found that babies delivered via C-section were more likely to be born in respiratory distress than those delivered vaginally (39% vs 26%).
More infants born via C-section also scored poorly on Apgar tests, the researchers reported Wednesday in Obstetrics & Gynecology.
Between seven and eight preemie deliveries would have to be switched from C-sections to vaginal births to avoid one case of newborn respiratory distress, they calculated.
"In general, people have thought that vaginal delivery would be preferred if there was no other indication, but it's been a question that some people have felt is still open for research," Dr. Henry Lee, from Stanford University School of Medicine's Division of Neonatal & Developmental Medicine, told Reuters Health.
It's still unclear whether there are certain types of babies, or certain situations, in which C-sections might be helpful, added Dr. Lee, who wasn't involved in the new research.
Dr. Werner said that because the researchers looked back at old records, they were not able to control for all differences between women who had C-sections and vaginal deliveries - a "huge limitation" of the study.
"I was struck by the fact that there does seem to be an increased risk of some things with C-section," she told Reuters Health. However, "I don't know if you can make a definitive statement that it is higher risk to have a C-section based on this study."
But Dr. Lee agreed that the evidence points toward vaginal deliveries in many scenarios.
"When there is no clear maternal medical reason or indication for the baby's health (to do a C-section), then the vaginal route would be the preferred route of delivery," he said.
Obstet Gynecol 2013.
Reuters Health Information © 2013