Thousands of women put their babies at needless risk of respiratory problems, hypoglycemia and other medical ailments by scheduling cesarean-section deliveries too early, according to an analysis of more than 13,000 births published in today’s New England Journal of Medicine.
Elective cesareans performed after only 37 or 38 weeks of pregnancy had up to four times the risk of serious complications compared with procedures done after 39 weeks. Even deliveries that were just one, two or three days shy of 39 weeks carried a 21 percent increased risk of complications, the study found.
“It looks like a day or two makes a difference,” said Dr. John Thorp, a professor of obstetrics and gynecology at the University of North Carolina in Chapel Hill and co-author of the study.
The initiation of labor is a baby’s way of signaling that it is ready to live outside the womb, Thorp said. When doctors schedule elective cesareans, “we’re saying we’re smarter than that signal,” he said. “There are some babies who aren’t ready to make that transition and are forced to do so.”
There were 1,262 cases involving some kind of complication among the 13,258 elective cesareans examined in the study. The rate of adverse outcomes was 15.3 percent after 37 weeks, 11 percent after 38 weeks and 8 percent after 39 weeks.
More than one-third of the women in the study delivered earlier than the recommended 39 weeks — 6 percent after 37 weeks and 30 percent after 38 weeks. Those mothers were more likely to be white, married and privately insured, the study found.
They probably scheduled their deliveries on the early side to avoid any risk of going into labor at a time when their doctors might not be available to care for them, Dr. Michael F. Greene, the chief of obstetrics at Massachusetts General Hospital in Boston, wrote in an accompanying editorial.
The study results suggest that the seven days during the 40th week of pregnancy is the safest time to schedule an elective cesarean, Thorp said. That window is “smaller and more tightly bound” than previously thought, he said.
