Folic Acid Doesn't Increase Miscarriage Risk

Though the benefits of taking folic acid supplements to prevent certain birth defects is firmly established, a study from several years ago found that women who took a multivitamin containing 800 micrograms of folic acid before and during early pregnancy had an increased risk of miscarriage.

But now a new study, published in the Sept. 8 issue of the Lancet, shows no increased risk of miscarriage among women who took 400 micrograms of folic acid before and during early pregnancy. In the study, women who had or had not taken folic acid supplements before and during the first trimester of their pregnancy had roughly the same rate of miscarriage, report researchers from the CDC in Atlanta and Peking University Health Sciences Center in Beijing.

Current recommendations state that all women who can become pregnant take a multivitamin that contains 400 micrograms of folic acid every day, beginning before conception and continuing into the early months of pregnancy, as part of a healthy diet including foods containing folic acid, such as leafy green vegetables, orange juice, peanuts, beans, and fortified grains.

Experts agree that the new study results further reinforce this message.

Folic acid supplementation before conception and during the first trimester of pregnancy is known to reduce risk for neural tube birth defects. Such birth defects including spina bifida and anencephaly affect 4,000 pregnancies per year, resulting in 2,500 to 3,000 U.S. births annually.

Spina bifida, or open spine, occurs when the backbone never closes completely and is a leading cause of childhood paralysis. Anencephaly is marked by a severely underdeveloped brain and skull.

Half of all pregnancies in the U.S. are unplanned. The neural tube forms by 28 days, so women must take folic acid on a daily basis before conception since weeks can go by before pregnancy is confirmed.

"[The new study] is good news," says study author R.J. Berry, MD, a medical epidemiologist at the CDC. "Taking folic acid before and during early pregnancy is safe and doesn't increase risk of miscarriage."

The original study that found an increased miscarriage risk among women consuming folic acid was not designed to look for miscarriages and was testing a whole pill containing 800 micrograms of folic acid and other vitamins and minerals, "but we looked at folic acid alone and miscarriage risk," Berry says. "We don't feel that dosage makes any difference."

The real problem with folic acid supplementation is that just under 30% of women are taking it before and during early pregnancy, he tells WebMD.

The new findings " reinvigorate the need to encourage women to take folic acid prior to conception. It really reaffirms that safety ... in an eloquent and scientifically strong way," says Donald R. Mattison, MD, medical director for the March of Dimes, based in White Plains, N.Y. The March of Dimes is a national voluntary health agency aimed at improving the health of babies by preventing birth defects and infant mortality.

"The bottom line is that we never engage in a public health intervention without worrying that there might be some adverse consequence, and one of the concerns that has arisen is related to whether consuming folic acid increased risk of spontaneous abortion or miscarriage, and this study shows that it does not," he tells WebMD.

"Not only is folic acid effective in reducing neural tube defects, but based on what we know it also appears to be safe," Mattison says.