Elective C-Section: 38th Week Too Soon

Elective C-Section: 38th Week Too Soon

Dec. 11, 2007 -- Babies born by elective C-section before the 39th week ofpregnancy have a three- tofourfold higher risk of breathing trouble than babies whose mothers havea?normal vaginal delivery.

Elective C-section babies also have a fivefold higher risk of needingmechanical breathing assistance for serious respiratory trouble, find AnneKirkeby Hansen, MD, and colleagues at Denmark''s Aarhus University Hospital.

"Mothers who choose elective cesarean section should be aware that therisk of respiratory problems is four times raised at 37 weeks'' gestation vs.full-term, intended vaginal delivery," Kirkeby Hansen tells WebMD. "Therate of respiratory problems is 10% for elective C-section at 37 weeks, but itis 2.8% for intended vaginal deliveries. That is why we say you should never doelective cesarean section at 37 weeks."

Kirkeby Hansen and colleagues gathered data on the 34,458 babies born inAarhus, Denmark, from 1998 through 2006. Nearly 2,700 of these infants weredelivered via elective C-section -- that is, the mother or her obstetricianopted for C-section without having a medical need to so.

The researchers compared these infants to infants from women who tried tohave 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 electiveC-section at 37 weeks'' gestation had a 3.7-fold higher risk -- and at 38 weeks,a 3.0-fold higher risk -- oftransitory tachypnea of the newborn (a condition sometimes called wet lung),respiratory distress syndrome, or persistent pulmonary hypertension (dangerously high blood pressure in thelungs).

All of these conditions mean that a baby is placed in an incubator in theneonatal intensive care unit for two days or so, Kirkeby Hansen says.

Most children fully recover from these breathing problems, notes EmoryUniversity pediatrician Lucky Jain, MD. But the long-terms effects aren''tclear.

"Sometimes these babies get into bigger trouble in the neonatalICU," Jain tells WebMD. "And what we don''t yet understand well is theimpact of two or three or four days of separation from the mother, of notinitiating breastfeeding, and of exposureto bacteria that are not normally found in our bodies."

Although it happened much less often, the Danish researchers found thatchildren delivered via elective C-section at 37 weeks'' gestation have afivefold higher risk of serious breathing problems requiring oxygen therapy, acontinuous positive air pressure device, or mechanical ventilation. Forelective C-sections at 38 weeks'' gestation, this risk is 4.2 times higher thanfor 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 theenormous challenge of making the transition to breathing air. Its fluid-filledlungs must clear quickly, Jain notes.

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