Antioxidants don't protect against a common condition in pregnant women that can lead to premature birth, low birthweight, and—in severe cases—death of the mother or her baby, a study published in The New England Journal of Medicine has found.

Pre-eclampsia, a disorder characterized by hypertension and protein in the urine, occurs in the second half of some 5% to 10% of pregnancies. Symptoms can include swelling, headaches, and changes in vision. Pre-eclampsia is a major cause of death among pregnant women in developing countries and is the root of 15% of premature births and associated complications in the U.S., the NEJM reports.

Since low levels of antioxidants have been linked to pre-eclampsia, some scientists had suggested that women given extra antioxidants would be better defended against the condition. To test the hypothesis, an Australian team conducted a randomized trial of 1,877 women who were between 14 and 22 weeks into their pregnancy. All were pregnant with their first child—first-time mothers are at greater risk—and were healthy, with normal blood pressure when the trial began. The women were given 1000 mg of Vitamin C and 400 IU of Vitamin E, both of which are antioxidants.

The results showed little impact. The women who took vitamin supplements did not have significantly lower rates of developing pre-eclampsia. Nor were rates of low birthweight, or serious illness or death in the infant meaningfully different.

What It Means: Healthy pregnant women will not decrease their odds of pre-eclampsia by taking antioxidants. In fact, scientists know of little that can be done to prevent pre-eclampsia: calcium and low-dose aspirin have not had meaningful effects on the condition in other studies either.

It's still unclear, however, whether vitamin treatment might be more beneficial to women in the Third World, where diet may include fewer antioxidants. But at least one study in developed nations—published in The Lancet earlier this year—found that women at increased risk of pre-eclampsia who were given antioxidants actually had even higher rates of certain complications, including low birthweight, than those in the placebo group. Given the minimal benefits of antioxidant vitamins and the possible risks, researchers do not recommend regular use of the supplements to prevent pre-eclampsia.

From the Archive:
03/30/2006 Antioxidant Overload and Pregnancy
10/28/2004 Born Too Soon