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Study finds vitamin D supplementation during pregnancy improves metabolic profiles but has no effect on preeclampsia.

Posted on: May 31, 2015   by  John Cannell, MD


Preeclampsia is a disorder characterized by pregnancy-induced hypertension and protein in the urine that occurs after 20 weeks of gestation. Preeclampsia can lead to eclampsia (generalized seizures), which increases both maternal and fetal death rates.

Preeclampsia has been reported to occur in about 2% to 6% of all pregnancies. Despite numerous attempts at early diagnosis and treatment, to date, no method has been found to prevent preeclampsia. Increased biomarkers of oxidative stress are considered to be a key factor in the development of pre-eclampsia.

In a randomized controlled trial, Professor Zatollah Asemi, PhD, Department of Nutrition, Kashan University of Medical Sciences and colleagues in Iran, gave 30 pregnant women at risk for preeclampsia (as determined by ultrasound) 50,000 IU of vitamin D3 every two weeks from 20 to 32 weeks of gestation. Thirty pregnant women who were also at risk for preeclampsia were given placebo for the same time periods. Both groups had similar characteristics at baseline.

Karamali M, Beihaghi E, Mohammadi AA, Asemi Z. Effects of High-Dose Vitamin D Supplementation on Metabolic Status and Pregnancy Outcomes in Pregnant Women at Risk for Pre-Eclampsia. Horm Metab Res. 2015 May 4. [Epub ahead of print].

The researchers took blood at week 12 and again at week 32 of gestation, measuring various indicators of inflammation and glucose metabolism. The baseline 25(OH)D of both groups were about 17 ng/ml. The treatment group’s 25(OH)D status increased to a mean of 34 ng/ml at week 32; whereas the placebo group’s 25(OH)D status remained the same.

Insulin levels went from 10 to 20 μIU/ml in the placebo group but only from 11 to 12 μIU/ml in the treatment group (p < 0.001). Three measurements of insulin sensitivity were better in the treatment group than the placebo group (p < 0.001). Total antioxidant capacity was improved in the treatment group than the placebo group (p = 0.001). However, other measurement of antioxidants and inflammation were not different between groups such as glutathione and hs-CRP. Serum lipids were not different between groups, except for HDL cholesterol, which was significantly improved in the treatment group.

At birth, one of the women in the vitamin D group developed preeclampsia while 3 in the placebo group did, but this was not statistically significant (p = 0.3). Two of the women in the placebo group had low birth weight infants while none in the vitamin D group did, but again, this was not statistically significant.

While the average vitamin D level in the treatment group was 34 ng/ml, the authors did not comment on the percentage of women in the treatment group who were still deficient.

The Vitamin D Council recommends anyone thinking of conceiving a child either get adequate sunshine or take 5,000 IU a day. We think pregnant women and women who are breast-feeding should get adequate sunshine or take 6,000 IU/day.

1 Response to Study finds vitamin D supplementation during pregnancy improves metabolic profiles but has no effect on preeclampsia.

  1. Tom Weishaar

    The lack of statistical significance looks more like a problem with the very small sample size than a problem of no effect. Since 3 out of 30 in the control group had preeclampsia vs. 1 out of 30 in the vitamin D group, we’re seeing an effect in the expected direction. In a meta-analysis this study would have an effect size of about .27. – Tom

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