Studies showing that Accutane, an acne drug derived from Vitamin A, is as serious a cause of birth defects as thalidomide have raised concerns that vitamin A itself might cause birth defects, a researcher says.

Dr. Edward Lammer of the California Birth Defects Monitoring Program reported Thursday that Accutane is as hazardous as thalidomide, causing 40 percent of women to miscarry and 25 percent to have children with severe birth defects if the women take it early in pregnancy.Thalidomide caused an epidemic of birth defects in Europe in the late 1950s and early 1960s before it was withdrawn from the market.

In a separate report earlier in the meeting, Lammer said that another drug related to Accutane, called Tegison, also appears to cause birth defects.

Tegison, or etretinate, made by Hoffmann-La Roche of Nutley, N.J., additionally has the unfortunate ability to remain in the body for as long as two years after women stop taking it, Lammer reported.

"It poses a risk of birth defects even for people who stop using it before they conceive," he said. The drug is used to treat psoriasis.

Both Accutane and Tegison are derivatives of vitamin A. Lammer said that raises the possibility that vitamin A itself might cause birth defects.

That is especially troubling because many multiple vitamin supplements intended to be taken during pregnancy contain vitamin A, Lammer said. He said there is little evidence that vitamin A has any benefits in pregnant women.

In a presentation in New Orleans at the annual meeting of the American Society of Human Genetics, Lammer reported that miscarriages occurred in 12 of 30 women studied, or 40 percent. Major birth defects occurred in 12 of 48 women studied, or 25 percent, he said.