Children born by Cesarean section before thirty-nine weeks in the womb are more likely to have immediate health problems than those born at thirty-nine or forty weeks, according to researchers writing in The New England Journal of Medicine. They studied women whose C-sections were elective and who had undergone a C-section before, but not those carrying more than one baby.

The study reviewed cases of more than thirteen-thousand C-sections performed at nineteen medical centers across the nation.

Researchers found that children born at thirty-seven or thirty-eight weeks in the womb… technically considered “at term”… experienced more instances of respiratory difficulties, low blood sugar and newborn sepsis. The babies were also more likely to require a ventilator, to be admitted to the neonatal I-C-U and to be hospitalized for at least five days.

The earlier the child was born, the more his or her risks increased. Children born after forty weeks in the womb were also more likely to experience some of the same difficulties.

The women who delivered earliest tended to be older and to have a lower body mass index.

The authors state that a significant number of elective C-sections take place before thirty-nine weeks. The trend might be explained, they said, by mothers wanting to deliver once they are considered to be “at term”… and by doctors who like to plan deliveries to fit into their schedules. But the researchers say their findings support those who advocate waiting until at least thirty-nine weeks to schedule elective Cesarean sections.