A previous study that reported reduced levels in
early pregnancy of serum 25-hydroxyvitamin D for women
who later developed pre-eclampsia [7], prompted
a study of the relationship between vitamin D supplementation
and pre-eclampsia. It was found that the
relative risk of pre-eclampsia for women with a total
vitamin D intake of 15-20 grams per day compared to
less than 5 grams per day was 0.76 (95% CI: 0.60-
0.95) [8]. No effect of dietary vitamin D alone was
found. This protective effect is in line with other reports,
although it has recently been concluded that the
quality of evidence is insufficient to determine a causal
association between vitamin D and pre-eclampsia [9].