The objective of the study was to examine if exposure to extra vitamin D from food fortification was associated with a decrease in the risk of preeclampsia. The study was based on a natural experiment exploring the effect of the abolition of the Danish mandatory vitamin D fortification of margarine in 1985. The effect of the extra vitamin D (1.25μg vitamin D/100 g margarine) was examined by comparing preeclampsia risk in women who have been exposed or unexposed to extra vitamin D from the fortified margarine during pregnancy, and who gave birth in the period from June 1983 to August 1988. The Danish National Patient Registry allowed the identification of pregnancies complicated by preeclampsia. The study included 73,237 women who gave birth during 1983-1988. We found no association between exposure to vitamin D fortification during pregnancy and the risk of any of the pregnancy related hypertensive disorders, including preeclampsia: Odds ratios (OR, 95%) for all hypertensive pregnancy related disorders among exposed vs. unexposed women was (OR 1.04, 95%CI: 0.98,1.10). In conclusion, the extra vitamin D from the mandatory vitamin D fortification did not influence the risk of preeclampsia.