While the C-section rate in the U.S. has climbed to one in three births — a 60 percent increase since 1996 — the rate at birth centers has stayed the same for more than 20 years.

Cesareans are associated with increased maternal mortality and morbidity, and those risks significantly increase with subsequent C-sections. Death and intensive-care stays also become more likely for babies.

Because most women who have C-sections end up having repeat C-sections in subsequent pregnancies, the new guidelines focused on practices that could prevent the surgery in healthy first-time mothers.

The two biggest reasons first-time mothers have cesareans are subjective: Doctors consider labor “stalled” or determine the electronic fetal heart rate readings are “nonreassuring.” But the latest evidence shows that labor lasts much longer than long thought, and little information exists on how to interpret questionable but common heart rate patterns.

Electronic heart rate monitors — which are tied around the woman’s belly and keep her immobile — are used in 85 percent of hospital births, but they aren’t to be seen at the O’Fallon birth center. Henman said midwives use a hand-held doppler to occasionally monitor the baby’s heart rate during the active phase of labor, when the woman’s cervix dilates rapidly.