Review of vitamin D deficiency during pregnancy: who is affected?

OBJECTIVES Vitamin D deficiencies have been documented in several populations, including aboriginal Canadians from isolated northern communities. Such deficiencies can impact the health of both the mother and her infant. This review was performed to determine how widespread vitamin deficiency is during pregnancy. STUDY DESIGN Electronic literature search. METHODS A Medline search was conducted using the Mesh terms "pregnancy" and "vitamin D". Those studies meeting the inclusion criteria were reviewed. RESULTS 35 of 76 studies reported deficient mean, or median, concentrations of 25(OH)D. Low concentrations were reported among different ethnic groups around the world. In addition, deficient concentrations were identified in 3 northern First Nations communities in Manitoba. CONCLUSIONS Such deficiencies are of concern, as the developing fetus acquires its 25(OH)D across the placenta and may influence infant health. Future research is required to resolve the discourse surrounding ambiguous threshold values for vitamin D deficiencies and insufficiencies and to identify effective strategies to improve the vitamin D status of expectant women. Vitamin D supplementation may be necessary for many women during pregnancy, especially those in northern regions where endogenous synthesis may be constrained.