Lindsey Cool was nearing the end of labor at the St. Alphonsus Regional Medical Center in Boise, Idaho, in 2003 when her doctor decided to use internal electronic fetal monitoring. An electrode was attached to the baby's scalp to monitor his heart rate. Everything was fine during contractions; the heart rate was within normal limits. "After I began pushing, the monitor fell off," Cool said. "My doctor panicked." Without Cool's consent, he ordered a vacuum extraction—a procedure in which a cup is attached to the baby's head and a vacuum pump is used to pull the child from the birth canal. He "ripped my son out," Cool said. She required stitches, and she "almost lost my right labia." After that dramatic intervention, there was no sign that the baby had any heart or breathing trouble.

Electronic fetal monitoring—which also includes external monitoring, in which an ultrasound transducer is placed on the mother's stomach—is supposed to prevent deaths by alerting the doctor to complications that would require an emergency Cesarean or vacuum extraction. Which sounds logical enough: The more you monitor the baby, the more likely you are to catch problems instantly. But study after study has proven that EFM is not logical at all, as it provides no benefit to most patients and creates more problems than it catches.

A federal Centers for Disease Control and Prevention review of controlled studies of EFM found "that routine use of the procedure had no measurable effect on death or illness of infants or mothers," The New York Times reported. "But they said electronic monitoring was associated with a higher rate of Caesarean deliveries, which increases surgical risks to mothers." That's from an article published 20 years ago. Fast forward to a 2013 review of 13 studies, involving more than 37,000 participating women, by the independent Cochrane Pregnancy and Childbirth Group. It found no correlation between EFM and reductions in fetal death.

And yet, EFM is more popular than ever. It's used on 85 percent of pregnant women, up from 45 percent in 1980. In fact, it's the single most widely used obstetric practice in the United States.

So why, despite decades of overwhelming evidence, do doctors and patient alike continue to insist on this largely useless and sometimes dangerous procedure?