Babies delivered by elective Caesarean sections are significantly more likely to have respiratory problems than those delivered vaginally or by emergency surgery, a new study finds. Researchers studied 34,458 successive live single births at a hospital in Aarhus, Denmark; 2,687 were elective Caesareans. The study was published online in The British Medical Journal.

The younger the gestational age, the more breathing problems there were for all babies, and the authors emphasised that the risk was small for all groups. Still, the increased risk for the elective Caesarean babies was notable. At 37 weeks, they were almost four times as likely as others of the same gestational age to have respiratory problems, at 38 weeks three times as likely, and at 39 weeks almost twice as likely.

The differences remained even after controlling for maternal age, smoking, alcohol intake and other variables.

The reason is unclear. The researchers theorise that hormonal and physiological changes in labour might help foetal lungs mature properly.

New York Times