Folic Acid Won’t Cause Miscarriage

If you’re pregnant and taking folic acid to prevent birth defects, you’re no more likely to miscarry than women who don’t take the B vitamin, says new research.

A link between miscarriage and the vitamin had been suspected, especially when previous studies suggested that women who took folic acid might have up to a 16 percent greater risk of miscarrying. But no real proof existed because scientists could not find a large group of women of childbearing age whose vitamin intake habits were known.

Enter the Chinese Ministry of Health.

“This new finding grew out of a larger and earlier cooperative study done with the Chinese government that helped to establish that 400 micrograms of folic acid without any other vitamins could help prevent neural tube defects,” says Dr. R. J. Berry, a medical epidemiologist with the Centers for Disease Control and Prevention in Atlanta. “That’s the only time folic acid alone, at that dose, had been looked at.” The results of that study were published in 1999.

Taking this amount of folic acid daily can slash the risk of neural tube birth defects by up to 70 percent, research has shown. The neural tube is the part of the fetus that develops into the brain and spinal cord, and defects here usually happen within four weeks of conception, according to the March of Dimes.

“Two studies in the early ’90s done to show that folic acid could prevent [neural tube defects] contained some other outcomes,” Berry explains. “And so there was some interpretation from that data that showed that women who took vitamin drugs online that contained folic acid had a higher rate of miscarriage — as high as 16 percent. But we could neither prove nor disprove the findings.”

In 1993, China started a program to get women to take folic acid. Women who were registered for marriage or who reported pregnancy in 21 counties were given a bottle of 31 folic acid pills each month, and their usage of the supplement was documented for the first three months of pregnancy. The outcomes of their pregnancies then were compared with women who had not taken folic acid.

“Again, this is the first study that could separate out folic acid alone,” Berry explains. “And the results showed that there was practically no difference in miscarriage rates between those who had taken folic acid before and during the first three months of pregnancy, and those who did not.”

The rate of miscarriage for women who took folic acid was 9.1 percent compared with 9.3 percent for women who did not take the supplement, the study shows. The findings appear in the Sept. 8 issue of The Lancet.

In 1992, the U.S. Public Health Agency recommended that all women should take 400 micrograms of folic acid daily. In 1998, the Institute of Medicine joined in that recommendation.

You can get the vitamin in two ways. Folic acid, a synthetic form of the nutrient, is found in vitamins and fortified foods. Folate is the natural form of the B vitamin, and it’s in orange and other citrus juices, green leafy vegetables and broccoli, beans and the like.

The March of Dimes says many pregnancies involving neural tube defects end in miscarriage or stillbirth, but about 2,500 babies are born each year with the defects. The most common disorder is spina bifida, a leading cause of childhood paralysis. Another common neural tube defect is anencephaly, a fatal condition in which a baby is born with an underdeveloped brain and skull.

Dr. Donald Mattison, medical director for the March of Dimes, headquartered in White Plains, N.Y., calls the study welcome news.

“It’s almost impossible to do any health intervention of any kind without being concerned about some potential adverse effect,” he says. “And one of the issues that was raised in the context of folic acid was the risk of miscarriage.”

“This study clearly demonstrates the safety of folic acid in the context of miscarriage,” Mattison says.

“Given the known benefits of folic acid, this study should provide additional reassurance and encourage women of reproductive age to take the recommended 400 micrograms of folic acid each day,” he adds.

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