Vitamin D deficiency during pregnancy has been associated with the development 
of several adverse health outcomes, e.g., pre-eclampsia, gestational diabetes 
mellitus, preterm delivery, low birth weight, birth length, and bone mineral 
content. The aims of the present study were to estimate the intake and sources 
of vitamin D in Danish pregnant women and to examine potential determinants of 
vitamin D intake of the recommended level (10 µg per day). In 68,447 Danish 
pregnant women the mean ± SD for vitamin D intake was 9.23 ± 5.60 µg per day 
(diet: 3.56 ± 2.05 µg per day, supplements: 5.67 ± 5.20 µg per day). 67.6% of 
the women reported use of vitamin D supplements but only 36.9% reported use of 
vitamin D supplements of at least 10 µg. Supplements were the primary source of 
vitamin D for the two higher quartiles of total vitamin D intake, with diet 
being the primary source for the two lower quartiles. Determinants of sufficient 
total vitamin D intake were: high maternal age, nulliparity, non-smoking, and 
filling out of the Food Frequency Questionnaire (FFQ) during summer or fall. We 
propose that clinicians encourage vitamin D supplementation among pregnant 
women, with special focus on vulnerable groups such as the young, smokers and 
multiparous women, in order to improve maternal and fetal health both during and 
after pregnancy.