While a cesarean delivery is sometimes necessary and can be lifesaving, it may have serious long-term disadvantages for both mother and child, researchers report.

The analysis, in PLOS Medicine, pooled data from 80 studies with almost 30 million subjects.

Compared to vaginal delivery, C-sections were associated with a significant reduction in the risk for urinary incontinence and for pelvic organ prolapse, a dangerous weakening of the muscles that hold pelvic organs in place.

But for a pregnancy after a cesarean, there was a 17 percent increased probability of miscarriage and a 27 percent increased probability of stillbirth. The researchers also found nearly triple the probability for placenta accreta, in which the placenta grows too deeply into the uterine wall, and an increased chance of other placental problems.

Children delivered by cesarean had a 21 percent increased probability of asthma by age 12 and a nearly 60 percent increased likelihood of obesity up to age 5.

Still, the absolute risks of delivery-related problems were small. “Both kinds of delivery have very low risks of complications,” said the senior author, Dr. Sarah Stock, an obstetrician at the University of Edinburgh. “With placenta accreta, for example, the risk is 1 in 3,000, and it goes up to 3 in 3,000 with cesarean. These are rare but serious risks.”

— New York Times News Service