Health News
Folate in 2nd trimester helps prevent preeclampsia

Feb 2, 2008, 07:17

 Taking multivitamins that contain folate, also referred to as folic acid, early in the second trimester of pregnancy may help reduce the risk of preeclampsia, the results of a study conducted in Canada indicate.

According to the researchers, led by Dr. Shi Wu Wen at the University of Ottawa, adequate levels of folate may play an important role in the development of the placenta. Folate appears to have a beneficial effect on endothelial cells, special cells that line blood vessels throughout the body and in the placenta.

Preeclampsia, also called toxemia of pregnancy, is a rapidly progressive disorder characterized by protein in the urine and high blood pressure. This may be followed by swelling and sudden weight gain, as well as headaches and changes in vision. However, some women may experience progression of the condition with few symptoms.

Affecting at least 5 to 8 percent of all pregnancies, preeclampsia and other blood pressure disorders of pregnancy are a leading global cause of maternal and infant illness and death.

Pre-eclampsia may progress to eclampsia, a more serious condition in which seizures begin to occur. Complications of eclampsia include separation of the placenta and premature delivery.

Preeclampsia is currently believed to be a two-stage disorder, Wen told Reuters Health. During stage I, which probably begins in the late first trimester or early second trimester, there is a decrease in blood flow in the placenta.

During stage II, which probably begins in the early third trimester, the syndrome of preeclampsia develops, caused by abnormalities of the mother's endothelial cells. Impaired blood vessel formation, inflammation, and nervous system abnormalities may all be contributing factors, the researcher explained.

They hypothesized that large doses of folic acid in early pregnancy may work at both stages of preeclampsia.

Wen and colleagues followed nearly 3,000 pregnant women who were seen for prenatal care between week 12 and week 20 of pregnancy. Their findings appear in the American Journal of Obstetrics and Gynecology.

A total of 2,713 (92 percent) women were taking folic acid alone or multivitamins that contained folic acid, usually at doses of 1.0 milligrams or higher.

As the researchers suspected, folic acid supplements led to a lower rate of preeclampsia. Preeclampsia developed in 2.17 percent of women taking folic acid and in 5.04 percent of those not taking supplements.

After the researchers adjusted the data to take into consideration the influence of maternal age, ethnicity, education level, number of previous pregnancies, body weight, income, smoking, high blood pressure, diabetes and history of preeclampsia, Wen's group found that folic acid reduced the risk of preeclampsia by about two thirds.

Whether the women started folic acid supplements -- before or after conception -- or whether the women discontinued or continued folic acid in the third trimester, "the rate of preeclampsia was...lower than in those women who did not have supplementation," Wen's team reports.

The doctors conclude that "for preeclampsia prevention, folic acid supplementation in the late first trimester or early second trimester, the most critical time window for preeclampsia development, may be the most important."

Current guidelines recommend 4 mg or 5 mg of folic acid for women who have high-risk pregnancies or are at risk for neural tube defects, such as spina bifida, Wen said.

Very high doses of folic acid, however, can cause stomach problems, skin disorders and seizures.