Vitamin D status in Canadian pregnant women and their newborn infants: what levels protect against adverse pregnancy outcomes?

Vitamin D deficiency is known to exist within northern nations, such as Canada. It has been suggested that close to 70% of Canadians demonstrate some vitamin D insufficiency. Recent studies suggest that low vitamin D level during pregnancy is associated with adverse pregnancy outcomes such as preeclampsia, gestational diabetes, and infants who are small for gestational age. There is a lack of consensus on the optimal vitamin D level in pregnancy and more research is needed to address this knowledge gap. The purpose of this study is to determine vitamin D status from a large cohort of pregnant women from two Canadian provinces and to try to identify a threshold at which vitamin D status is protective against adverse pregnancy outcomes for mother and infant. This study will provide information, in a timely and cost-efficient manner, critically needed for defining optimal vitamin D status in pregnancy. This information can then used for the development of guidelines pertaining to vitamin D supplementation during pregnancy.