One study showed that halibut liver oil supplementation (900 IU of vitamin D per day) beginning at week 20 of gestation decreased the odds of preeclampsia by 32%, but these women were receiving a dietary supplement that contained other vitamins, minerals, and fish oil in addition to the halibut liver oil1.

While a second randomized controlled clinical trial, demonstrated that vitamin D (1200 IU/d) plus calcium (375 mg/d), started at 20-24 wk of gestation significantly reduced blood pressure (p <0.001) compared to placebo-treatment2.

The study by Bodnar et al3 gives an estimate of the effect of vitamin D in preventing preeclampsia. Risk of preeclampsia decreased from 25% for 5 ng/ml to 15% for 40 ng/ml.

Page last edited: 03 May 2011


  1. Olsen, S. F. Secher, N. J. A possible preventive effect of low-dose fish oil on early delivery and pre-eclampsia: indications from a 50-year-old controlled trial. Br J Nutr. 1990 Nov; 64 (3): 599-609.
  2. Marya, R. K. Rathee, S. Manrow, M. Effect of calcium and vitamin D supplementation on toxaemia of pregnancy. Gynecol Obstet Invest. 1987; 24 (1): 38-42.
  3. Bodnar, L. M. Catov, J. M. Roberts, J. M. Racial/ethnic differences in the monthly variation of preeclampsia incidence. Am J Obstet Gynecol. 2007 Apr; 196 (4): 324 e1-5.