In 1918 in Philadelphia, members of the American Gynecological Society listened intently as Ralph H. Pomeroy read his trailblazing paper at their annual meeting.

It was time, he argued, for obstetrician-gynecologists to take more responsibility for preventing injuries to mother and baby during delivery.

"Why should we consider it other than reckless to allow the child's head to be used as a battering ram wherewith to shatter a resisting outlet?" asked the influential Long Island ob-gyn. "Why not open the gates and close them after the procession has passed?"

Metaphors aside, Pomeroy believed cutting the tissue between a woman's vagina and anus, known as the perineum, would speed delivery and decrease trauma. Just sew up the incision afterward.

Pomeroy and a contemporary, Chicago ob-gyn Joseph B. DeLee, are credited with turning "episiotomy" from an emergency surgical intervention into a routine procedure.

Alas, there was no evidence to support casually cutting this vitally important genital flesh. Worse, it wasn't until about 1980 that accumulating evidence began to debunk doctors' wishful thinking. By then, an annual federal survey showed episiotomy was performed in 64 percent of U.S. vaginal births, including 80 percent of first-time mothers.

The rate has been steadily falling since, and nine years ago, the American College of Obstetrician-Gynecologists officially recommended that "restricted use is preferable to routine use."

"It really comes down to reeducating physicians," said Alka Kohli, chief medical officer of the Virtua Health System in South Jersey, where less than 5 percent of its 8,000 deliveries last year involved episiotomy.

What is the ideal rate? As with cesarean section deliveries, too many factors are involved for experts to say. Episiotomies were done in nearly 12 percent of U.S. vaginal births in 2012, but wide variation among hospitals persists, a recent Columbia University study found.

"It's definitely due to provider preference," said lead author Alexander Friedman, director of maternal-fetal medicine at the Columbia University College of Physicians and Surgeons. "Some doctors are using the procedure way more frequently than they should."

As a baby's head gradually pushes through the mother's vaginal opening, the stretching tissue often suffers scrapes and splits.

"Those little tears are known as skid marks," said Virtua's Kohli, an ob-gyn. "You don't even need to sew them. They heal on their own."

Severe tears - the worst ones rip into the anal sphincter muscle and the rectum - are relatively rare, but are also hard to predict.

In the early 20th century, when Pomeroy and DeLee advocated the intentional widening of the vaginal opening with a snip of a few inches of the perineal membrane and muscles, it sounded logical.

In addition to abbreviating the painful climax of childbirth, episiotomy would prevent jagged tears, which were harder to repair. Theoretically, the wider opening would also reduce fetal distress and protect the fetal brain while sparing the woman from a passel of problems, including incontinence and sexual dysfunction.

This theory, however, was more about shifting medical and cultural beliefs than science. Midwives were being replaced by ob-gyns, some of whom believed childbirth was disease-producing, or "pathological."

As DeLee wrote in 1920, "If a woman falls on a pitchfork and drives the handle through her perineum, we call that pathologic - abnormal. But if a large baby is driven through the pelvic floor, we say that is natural. . . . If a baby were to have its head caught in a door very lightly, but enough to cause cerebral hemorrhage, we would say that it is decidedly pathologic, but when a baby's head is crushed against a tight pelvic floor, and a hemorrhage in the brain kills it, we call this normal."

Although the scientific rebuttal took many years, it prevailed in 1983. An esteemed epidemiologist at the U.S. Centers for Disease Control and Prevention led a landmark review of 350 books and studies published since 1860. The conclusion was damning: "There is evidence that postpartum pain and discomfort are accentuated after episiotomy, and serious complications, including maternal death, can be associated with the procedure."

Rather than preventing severe tears, episiotomy increased the risk - a finding used in some lawsuits. A 35-year-old Houston mother, for example, settled for $8.4 million in 2003 after doctors botched her episiotomy and repair operation, leaving her incontinent, in pain, and sexually dysfunctional.

So when is episiotomy appropriate?

The ob-gyns' guideline says "there is a place" for it when a tear seems imminent, or forceps are used, or the fetal heart rate plummets, or the baby's shoulder is stuck behind the mother's pubic bone after the head is out.

But even in those situations, the evidence is weak, so "clinical judgment remains the best guide," the group recommends.

There is no requirement to report episiotomies, and health-care-quality organizations such as the Leapfrog Group have only recently begun collecting the data from hospitals - on a voluntary basis. (See www.leapfroggroup.org/cp.) Most in the Philadelphia area, including Pennsylvania and Holy Redeemer Hospitals, declined to provide data to Leapfrog.

Pennsylvania Hospital, with the city's biggest maternity unit, also declined to give an interview for this article.

Holy Redeemer spokeswoman Barbara L'Amoreaux said the hospital's 2014 rate was "less than 25 percent. But that number is going down all the time."

Abington Memorial Hospital, with the biggest maternity unit in the Pennsylvania suburbs, said it did episiotomies in just under 5 percent of 4,800 deliveries last year.

"I don't think the number should be zero," said Amy Mackey, Abington's director of labor and delivery. "But I think, sometimes, we become impatient. If the baby looks good, we should give women time" to continue labor and slowly stretch tissues.

The Columbia study, published in January in the Journal of the American Medical Association, analyzed an insurance-claims database for 510 hospitals. First-time mothers who were white, had private insurance, and gave birth in nonteaching urban hospitals were more likely to have episiotomies. And though the national rate was about 12 percent, the range was wide: an average of 34 percent at the 51 hospitals that performed the procedure most often, compared to 2.5 percent at those that did it least.

Unlike doctors, midwives have always avoided it. The Birth Center, a midwifery practice in Bryn Mawr, performed episiotomies in about 2 percent of last year's 380 deliveries, clinical services director Julie Cristol said.

Though she advocates low-tech tissue-stretching tactics such as hot compresses, she has noticed factors that may help explain episiotomy disparities. For example, African American women, who have the lowest rates, have more skin pigmentation, and "the more pigmented your skin," Cristol said, "the more stretchy."

Ironically, women who are super-fit may be more likely to wind up with an episiotomy.

"The worst are yoga instructors, because their pelvic floors are like cast iron," Cristol said. "The baby just sits there, and nothing is stretched."

215-854-2720

@repopter