WASHINGTON - One in five pregnant women has her labor induced. The question: Did the doctor pick the best time to try to speed nature's course, or would waiting a few more days make for an easier delivery?
A simple vaginal test may soon help doctors choose the date.

If the

The potential new use would focus sharp attention on a controversial issue at the end of pregnancy: Are doctors performing too many inductions, in a quest for more convenient childbirth?

The proportion of women undergoing induced labor has more than doubled since 1989.

Many are required for medical reasons: to treat a mother's pregnancy-induced high blood pressure or diabetes, or because the baby is in distress, or the pregnancy has dragged beyond the due date.

But elective inductions are spurring much of the rise. Parents' busy schedules and the convenience of avoiding a mad late-night dash to the hospital aren't the only reasons. Perhaps her obstetrician is going on vacation and the mother doesn't want the stranger on call, or needs long-distance relatives to visit and help out.

Regardless of why they're done, timing is important: If an induction is tried when the mother-to-be's body isn't ready enough — especially a first-time mother — it can mean a prolonged labor ending in Caesarean section.

Enter the test for fetal fibronectin, or fFN, a protein that is considered sort of a uterine glue. If it seeps into the vaginal tract anytime from mid-pregnancy onward, it's thought to signal that membranes are breaking apart so that labor might begin fairly soon.

Until now, doctors have timed inductions largely with a manual exam of how soft and dilated the woman's cervix appears.

The problem: That's a very subjective test, says Dr. Michael Randell, an Atlanta obstetrician.

A solo practitioner, he estimates that 90 percent of his patients are induced. "We live in a Palm Pilot society. Everything is planned," Randell explains.

But he's anxiously awaiting FDA's verdict on whether the fFN test could help better time those labors, because that test could offer objective confirmation of the cervical exam.

If it came back negative — no sign of fFN — for a woman he'd hoped to induce that week, "I would not even consider it," Randell says. "Wait another week and retest."

Manufacturer Adeza Biomedical sponsored a 22-hospital study of the toughest cases, 875 first-time mothers all scheduled for inductions despite cervical exams suggesting they weren't the best candidates.

Women who had a positive fFN test — suggesting the body may have been preparing for natural labor — were 38 percent more likely to deliver vaginally within 24 hours of the induction's start than those with no detectable fFN. And women with negative fFN tests were 29 percent more likely to wind up getting a C-section.

Some doctors are skeptical, saying the test may only spur questionable inductions.

"I don't feel a crying need for this (test), and I don't feel this trend for elective inductions is a good thing," says Dr. Peter Bernstein of New York's Montefiore Medical Center.

If the test is positive, "you're more likely to induce, but that doesn't mean you're not going to wind up with a Caesarean," he warns.

The test already is used earlier in pregnancy.

Many doctors check for fFN o help determine if women experiencing preterm contractions — between weeks 24 and 34 of pregnancy_ really are going into early labor or are having a false alarm. If the fFN test is negative, those women have less than a 1 percent chance of giving birth in the next two weeks, and may be sent home with the warning to call a doctor if symptoms change.

A positive fFN test is much less accurate, iffy enough that obstetric guidelines don't recommend using it for routine monitoring.

Still, many doctors have begun using it on women considered at risk of preterm birth, giving the $200 test every two weeks in hopes of peace-of-mind results until they're 35 weeks along, when doctors no longer attempt to postpone delivery.

"I felt, 'Why not have an extra warning, a warning signal?'" said Marina Belica of New York, a singer who said the testing gave her the confidence to perform with her band, October Project, through her seventh month of pregnancy with twins Benjamin and Sarah. "I kept a fairly active schedule. Having this reassurance was vital."

For the same price, Montefiore's Bernstein prefers vaginal ultrasounds that painlessly measure if and how much a high-risk woman's cervix is changing in preparation for delivery — although he acknowledges the scans aren't easily available in rural areas.