LOS ANGELES — Contrary to the results of earlier studies, large quantities of vitamins C and E do not prevent preeclampsia, high blood pressure and other complications of pregnancy, researchers found in the largest study of the vitamins to date. British researchers reported about a decade ago that the vitamins, which are known to be antioxidants, lowered the risk of preeclampsia, but subsequent studies have yielded mixed results.
Preeclampsia, which affects about 6 percent of pregnancies, is a sudden increase in blood pressure, usually occurring after the 20th week of pregnancy. It can damage the mother’s kidney, liver and brain and lead to the death of the mother and infant if left untreated.
To examine the subject more thoroughly, a team headed by Dr. James Roberts of the University of Pittsburgh enrolled 10,154 pregnant women in the ninth to 16th week of their pregnancies. All were in their first pregnancy, were healthy and did not have hypertension or gestational diabetes. In addition to their normal pregnancy vitamins, half received 1,000 milligrams of vitamin C and 400 international units of vitamin E daily — about 10 times the normal daily dose — or a placebo.
The rate of preeclampsia was 7.2 percent among those taking the vitamins compared with 6.7 percent among those taking a placebo, a statistically insignificant difference. The rate of simple hypertension and other complications was 6.1 percent among those taking vitamins and 5.7 percent among those taking the placebo.
“These results are very useful,” said Dr. Catherine Spong of the National Institute of Child Health and Human Development in a statement. “In this case, it shows us that what originally appeared to be a promising treatment did not actually offer any benefit clinically.”
Roberts cautioned women against discontinuing their pregnancy vitamins, which are important to maintain the health of the mother and fetus. At the level of vitamins used in the study, he said, they should be considered drugs, not supplements.
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