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.
Based on those cases, researchers found that regardless of
why a C-section was performed - whether because of pregnancy-related
complications or the mother's medical problems, for example - vaginal delivery
tended to be safer.
"My suspicion is that the labour 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.
C-section procedures on the rise
The rate of C-sections in the United States has been rising
for all pregnancies, leading some to worry about possible complications for
mothers and babies. According to the US Centers for Disease Control and
Prevention, C-sections accounted for almost one in three births in 2010 - up from one
in five in 1996.There are certain circumstances - such as when a woman is bleeding
or a baby has a drop in heart rate - when a C-section is required, Werner said.
However, she said,
there hasn't been much data on whether C-section or vaginal delivery is the
generally safer method for other premature babies, who are more fragile than
full-term babies to begin with. Her team's data come from birth certificates
and hospital discharge records for 20 231 babies born in New York between 1995
Babies were born too
All were born very early, between 24 and 34 weeks. Normal
gestation is considered 37 to 42 weeks. Just over two-thirds of the babies were
born vaginally. After taking into account a mother's age, race and underlying
medical conditions, Werner and her colleagues found that babies delivered via
C-section were more likely to be born in respiratory distress.
Just over 39% of them had breathing problems, compared to 26%
of infants delivered vaginally. More infants born via C-section also scored
poorly on a test that measures overall health - including heart rate, reflexes
and skin coloring - five minutes after birth, 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.
women who had C-sections
It's still unclear whether there are certain types of
babies, or certain situations, in which C-sections might be helpful, added Lee,
who wasn't involved in the new research. 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 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.