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Vitamin D May Reduce Risk of Preeclampsia


A Norwegian study finds that vitamin D supplementation during pregnancy may reduce a mother’s risk of developing preeclampsia. Left untreated, preeclampsia can lead to eclampsia, a condition that can be deadly to both the pregnant woman and her infant.

According to the Preeclampsia Foundation, preeclampsia affects at least 5 to 8 percent of all pregnancies. It is a rapidly progressive condition characterized by high blood pressure and the presence of protein in the urine. Symptoms often include sudden weight gain, headache, vision changes, nausea and vomiting, and swelling. Preeclampsia typically occurs after 20 weeks’ gestation, although it can appear earlier.

The current study evaluated 23,423 would-be first-time mothers who participated in the Norwegian Mother and Child Cohort Study. For this study, the researchers asked the women to complete a general health questionnaire at the fifteenth week and thirtieth week of pregnancy and a food frequency questionnaire at week twenty-two.

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The investigators found that women who had consumed between 15 and 20 micrograms of vitamin D daily from their diet and supplements had a 24 percent lower risk of developing preeclampsia compared with women who consumed less than 5 micrograms daily. A slightly better benefit, 27 percent reduction in risk, was seen in women who took vitamin D supplements compared to women who did not take supplements.

Vitamin D is an antioxidant, and it was chosen for the study because oxidative stress has been proposed as a possible cause of preeclampsia. Other researchers have examined the possible role of the antioxidants vitamins C and E in the fight against oxidative stress in preeclampsia, but the results have been conflicting, with some studies indicating vitamin C may provide some benefit (but not vitamin E), and others showing no advantage. In the current study, however, vitamin D appears to provide some benefit.

Although vitamin D appears to be beneficial for reducing the risk of preeclampsia, the authors of the study note that in the Norwegian diet, dietary vitamin D intake is highly correlated with the intake of omega-3 fatty acids (found in fatty fish), and so additional research will need to look at the impact of this nutrient on their findings.

Haugen M et al. Epidemiology 2009 Sept; 20(5): 720-26
Klemmensen A et al. BJOG 2009 Jun; 116(7): 964-74
Preeclampsia Foundation website
Villar J et al. BJOG 2009 May; 116(6): 780-88