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High intake of folic acid do not protect pregnant women against preeclampsia. Preeclampsia is the leading cause of pregnancy-related complications and death worldwide, affecting about 10 million women a year. The most effective treatment is to deliver the baby, sometimes preterm. Medications, such as those to lower blood pressure, are also recommended for some women.
Folic acid is a B vitamin that helps cells grow. It is recommended for women who are trying to conceive and those who are in their first trimester of pregnancy, to prevent neural tube birth defects such as spina bifida. Previous research suggested high doses throughout pregnancy might offer some protection against preeclampsia.
The study included about 2,460 women in five countries who had at least one risk factor for preeclampsia -obesity, twin pregnancy, existing high blood pressure, pre-pregnancy diabetes or a previous history of preeclampsia. Each received up to 1.1 milligrams of folic acid daily throughout their pregnancy. About half were randomly chosen to also take a daily high-dose (4-milligram) supplement, starting at 8 to 16 weeks of pregnancy. The others took a placebo. About 15 percent of the women in the high-dose group developed preeclampsia, as did 13.5 percent of those who took the dummy pills not a meaningful difference.
Rates of stillbirth were also similar between the two groups, between 1 percent and 2 percent. In addition, the study found no difference between the groups for any other negative outcomes. Doctors routinely prescribe a baby aspirin for women who are at high risk of preeclampsia and an increasing number are recommending a double dose. He said a recent study of the diabetes drug metformin in pregnant women also found a small reduction in preeclampsia, but further investigation is needed.
The best way women can lower their risk is to plan their pregnancies, try to get in shape before conceiving and then follow doctors’ recommendations about weight gain during pregnancy. Preeclampsia may have genetic causes in some patients, while environmental exposure or immune system issues may increase the risk in some women.