COLUMBIA, S.C. (AP) - Birth defects in which the fetal brain and spine are malformed have dropped by half in South Carolina since a statewide campaign to increase women's folic acid intake began eight years ago, researchers reported Monday.

Folic acid - found naturally in green leafy vegetables, orange juice and liver - appears to be the key to prevention, said Dr. Roger Stevenson of the Greenwood Genetic Center, the lead author of the study published in the journal Pediatrics.

An accompanying commentary suggested that all women of childbearing age should consume 400 micrograms of folic acid daily, and the study said federal guidelines for the vitamin should be raised.

Three of the most serious birth defects - spina bifida, anencephaly and encephalocele - are caused when the neural tube, which forms the brain and spine, fails to close in the first 28 days of pregnancy.

When the study began in 1992, South Carolina's prevalence of neural tube defects was about 19 cases per 10,000 births, almost twice the national average, Stevenson said.

By 1998, that had dropped to fewer than 10 cases per 10,000. The number of women in the state taking folic acid during the study jumped from 8 percent to 35 percent - about the national average.

"We want to see all pregnancies protected," Stevenson said. "It's comparable to having 35 percent of our children protected against polio. This would not be acceptable."

Kim Gates, 31, of Charlotte, N.C., learned the impact of folic acid after her daughter Breanna was born with spina bifida seven years ago.

"I wasn't taking vitamins. I wasn't planning to get pregnant," Gates said. "But by the time I got ready to have my son, I knew the effects."

When Gates and her husband planned their second child, she requested a folic acid prescription from her doctor. Her son, Jonathan, was born three years ago without any problems.

The state's awareness campaign included ads on billboards, television and radio and in magazines.

"We saw increased vitamin use - particularly folate - after our campaign to increase awareness," said Roger Best, genetics division director at the University of South Carolina medical school and a member of the research team.

The researchers also followed up on 132 subsequent pregnancies and in the 113 cases where the mother took folic acid, there were no neural tube defects.

"This shows people that by taking the simple step of taking a vitamin every day, we can save babies," said Maureen Vicaria, director of program services for the South Carolina branch of the March of Dimes.

The results of the South Carolina study are similar to what was found during a Texas study, according to an accompanying commentary in Pediatrics.

"The campaign in South Carolina to reach all women of reproductive age was a success and a failure. It dramatically increased the proportion of women using supplements appropriately, but it reached less than half the women," wrote Drs. Donald Mattison of the March of Dimes, Godfrey Oakley Jr. of Emory University and Robert Brent of the Jefferson Medical College in Delaware.

The Food and Drug Administration in 1998 ordered manufacturers to begin fortifying foods with 140 micrograms of folic acid per 100 grams. Stevenson said the level should be increased two to three times to give women adequate protection.

Copyright 2000 The Associated Press. All rights reserved.