Vitamin D and the placenta

The physiological roles of vitamin D during pregnancy are diverse and complex with actions in the mother, placenta, and fetus affecting calcium homeostasis and cell proliferation as well as inflammation and immune function. It is necessary to distinguish the effects of vitamin D on the placenta and to recognize the placenta's role in determining vitamin D actions in the fetus. The current understanding of the physiology of vitamin D during pregnancy, specifically its interaction with the placenta will be discussed. We will also discuss the evidence base linking placental function and structure to fetal vitamin D supply and the mechanisms that could underlie this relationship and placental responses to maternal vitamin D levels, which could subsequently influence fetal development. Understanding the processes affecting these placental mechanisms is key to addressing clinical complications linked to impaired vitamin D status during pregnancy and designing effective interventions.