Too many pregnant women who want to avoid a repeat Caesarean delivery are being denied the chance, concludes a government panel that urged doctors to rethink litigation-spurred policies that have swung the pendulum back toward the days of "once a C-section, always a C-section."

Fifteen years ago, nearly 3 in 10 women who had a first C-section were able to deliver their next baby vaginally, a trend called VBAC for "vaginal birth after Caesarean."

Now that rate has dropped to 1 in 10, in part because a third of hospitals and half of physicians ban women from attempting VBAC, a panel of specialists convened by the National Institutes of Health said Wednesday.

But VBAC remains a safe alternative for the right candidates, and when those women try labor, between 60 percent and 80 percent of the time they do give birth vaginally, the NIH panel concluded. It urged that doctors offer mothers-to-be an unbiased look at the pros and cons, so they can decide for themselves.

"We believe that many women should have an opportunity to give it a try," said panelist and Delaware obstetrician Dr. Nancy Frances Petit of the U.S. Uniformed Health Services.

Overall, nearly a third of U.S. births are by C-section, an all-time high. Caesareans can be lifesaving but they come with certain risks — and the more C-sections a woman has, the greater the risk in a next pregnancy of problems like placenta abnormalities or hemorrhage.

Decades ago, doctors almost always recommended a repeat C-section, worried that the rigors of labor could cause a uterus scarred from the first surgery to rupture. But in 1980, government experts concluded that many mothers could safely deliver vaginally the next time, citing evidence that their risk of a uterine rupture was less than 1 percent.

Yet the last decade saw the pendulum swing back again: Among 19 states that track VBAC, 92 percent of women had a repeat Caesarean for their next delivery in 2006. And in 1999, the American College of Obstetricians and Gynecologists issued guidelines saying VBAC should be attempted only in hospitals equipped for immediate emergency surgery — and many smaller and rural hospitals aren't.

What sparked the latest shift? It's partly concern over litigation, the NIH panel said, because while a uterine rupture remains very rare, it can be devastating to the family and end in a high-dollar lawsuit.

Case-by-case decisions are crucial, the panel said, because there may be instances where another C-section is better for the baby but not for mom or vice versa.

Who's a good candidate? The panel said that needs further study. But in general, VBAC is for women who've had one prior C-section done with a "transverse" scar, the most common kind today, said panel chairman Dr. F. Gary Cunningham of the University of Texas Southwestern Medical Center at Dallas. Women should be otherwise low-risk, he said: Not carrying multiples or a large baby, being obese or having high blood pressure or diabetes.

"There's still a lot we don't know about which women will be successful in having a VBAC, but we believe it's essential that women's desires and preferences be respected throughout the decision-making process," Cunningham said.

Don't try to pre-judge candidates, said Dr. Emily Spencer Lukacz of the University of California, San Diego.

"All women who have prior Caesarean delivery should talk to their providers about VBAC," so they can decide on a case-by-case basis if it makes sense, Lukacz said.

It can be difficult for women to find a doctor or hospital that offers VBAC, said Debra Bingham of Lamaze International. She points to California, which now lists VBAC availability for every hospital on a Web site: http://www.calhospitalcompare.org.