A federal panel is recommending that all pregnant women, not just those considered at high risk, be screened for the AIDS virus because testing has proved so successful at helping prevent the spread of the disease to babies.

The U.S. Preventive Services Task Force said in 1996 that there was insufficient evidence that screening all pregnant women had any benefit. But the independent panel of medical experts said in today's Annals of Internal Medicine that scientific advances have changed that.

"We're hoping that this will encourage women to think of HIV testing during pregnancy the way they think of all other testing during pregnancy," said Dr. Diana Petitti, the task force's vice chairwoman and a scientific adviser for Health Policy and Medicine for Kaiser Permanente Southern California.

HIV-infected pregnant women can be given combination drug therapies, have Caesarean sections or avoid breast-feeding to help keep their babies safe, reducing the risk of transmission to as low as 1 percent, the task force said. Otherwise, infected women have a 1-in-4 chance of passing AIDS on to their babies.

Of the 4.7 million women hospitalized for pregnancy or childbirth in 2002, nearly 6,300 had HIV. About 40,000 Americans are infected with HIV each year, and about 27 percent of those are women.

Sharon Hillier, a professor at the University of Pittsburgh School of Medicine, said many women don't know they have the virus.

"It's astonishing how people still don't understand that this can happen to almost anybody. Women don't always know if their partners have had other sex partners," Hillier said.