Low vitamin D levels may cause pregnancy complications

According to a new Canadian review, insufficient blood vitamin D levels in pregnant women seem to be linked to gestational diabetes, preeclampsia and low birth weight of newborns.

The meta-analysis included 31 observational studies investigating the serum 25 hydroxyvitamin D concen-trations and courses of pregnancy of more than 7,000 women (1). The analysis showed that women with low vitamin D levels had an average 21% increased risk of developing gestational diabetes, a 35% increased chance of developing preeclampsia and a 43% increased chance of giving birth to a baby small for its gestational age. No significant differences were found in length and head circumference at birth.

The researchers commented that these results are concerning given recent evidence that vitamin D insufficiency is common during pregnancy, especially among high risk women (particularly vegetarians), women with limited sun exposure, and ethnic minorities with darker skin. Well-designed randomized controlled trials would be needed to determine the dose-response relationship between vitamin D supple-ments and improved pregnancy and neonatal outcomes. Supplements, diet and exposure to sunlight are ways of optimizing vitamin D concentrations, and these strategies should be used together.

1. Aghajafari F. et al. Association between maternal serum 25-hydroxyvitamin D level and pregnancy and neonatal outcomes: systematic review and meta-analysis of observational studies. BMJ. Published online March 2013.