Vitamin D, the placenta and pregnancy

Impaired vitamin D status is common to many populations around the world. However, data suggest that this is a particular problem for specific groups such as pregnant women. This has raised important questions concerning the physiological and clinical impact of low vitamin D levels during pregnancy, with implications for classical skeletal functions of vitamin D, as well as its diverse non-classical actions. The current review will discuss this with specific emphasis on the classical calciotropic effects of vitamin D as well as the less well established immunological functions of vitamin D that may influence pregnancy outcome. The review also describes the pathways that are required for metabolism and function of vitamin D, and the various clinical complications that have been linked to impaired vitamin D status during pregnancy.

► Vitamin D-insufficiency has been linked to adverse events of pregnancy.
► The placenta is the major extra-renal site for activation of 25(OH)D3 to 1,25(OH)2D3.
► Maternal serum levels of 1,25(OH)2D3 increase dramatically during pregnancy.
► In the placenta 1,25(OH)2D3 can promote antibacterial and anti-inflammatory actions.
► Supplementation with vitamin D may help to protect against adverse events in pregnancy.