Elective C-Section: 38th Week Too Soon
C-Section Before 39th Week Ups Baby Breathing Problems
WebMD News Archive
Dec. 11, 2007 -- Babies born by elective C-section before the 39th week of
pregnancy have a three- to
fourfold higher risk of breathing trouble than babies whose mothers have
a normal vaginal delivery.
Elective C-section babies also have a fivefold higher risk of needing
mechanical breathing assistance for serious respiratory trouble, find Anne
Kirkeby Hansen, MD, and colleagues at Denmark's Aarhus University Hospital.
"Mothers who choose elective cesarean section should be aware that the
risk of respiratory problems is four times raised at 37 weeks' gestation vs.
full-term, intended vaginal delivery," Kirkeby Hansen tells WebMD. "The
rate of respiratory problems is 10% for elective C-section at 37 weeks, but it
is 2.8% for intended vaginal deliveries. That is why we say you should never do
elective cesarean section at 37 weeks."
Kirkeby Hansen and colleagues gathered data on the 34,458 babies born in
Aarhus, Denmark, from 1998 through 2006. Nearly 2,700 of these infants were
delivered via elective C-section -- that is, the mother or her obstetrician
opted for C-section without having a medical need to so.
The researchers compared these infants to infants from women who tried to
have a vaginal delivery, including women who ended up having a C-section.
After adjusting for factors that might affect the infant's breathing,
Kirkeby Hansen and colleagues found that children delivered by elective
C-section at 37 weeks' gestation had a 3.7-fold higher risk -- and at 38 weeks,
a 3.0-fold higher risk -- of
transitory tachypnea of the newborn (a condition sometimes called wet lung),
respiratory distress syndrome, or persistent pulmonary hypertension (dangerously high blood pressure in the
All of these conditions mean that a baby is placed in an incubator in the
neonatal intensive care unit for two days or so, Kirkeby Hansen says.
Most children fully recover from these breathing problems, notes Emory
University pediatrician Lucky Jain, MD. But the long-terms effects aren't
"Sometimes these babies get into bigger trouble in the neonatal
ICU," Jain tells WebMD. "And what we don't yet understand well is the
impact of two or three or four days of separation from the mother, of not
initiating breastfeeding, and of exposure
to bacteria that are not normally found in our bodies."
Although it happened much less often, the Danish researchers found that
children delivered via elective C-section at 37 weeks' gestation have a
fivefold higher risk of serious breathing problems requiring oxygen therapy, a
continuous positive air pressure device, or mechanical ventilation. For
elective C-sections at 38 weeks' gestation, this risk is 4.2 times higher than
for intended full-term vaginal delivery.
Labor Good for Fetus
What does a C-section have to do with a newborn's ability to breathe?
As it leaves the liquid environment of the womb, a newborn faces the
enormous challenge of making the transition to breathing air. Its fluid-filled
lungs must clear quickly, Jain notes.