Inadequate vitamin D status in pregnancy: evidence for supplementation.

The role of vitamin D in maintaining a healthy pregnancy has seen emerging interest among clinicians and researchers in recent years. The functions of this hormone are widespread and complex, and during pregnancy and breastfeeding it facilitates crucial transfer of calcium from mother to child for skeletal development. Aside from the role of vitamin D in bone development and health, a myriad of other physiological actions are now known, and it is hypothesized that maternal deficiency may increase susceptibility to adverse pregnancy events during pregnancy such as pre-eclampsia. The role of vitamin D in pregnancy and breastfeeding is summarized and applied to the knowledge from studies associating vitamin D deficiency with a range of adverse pregnancy outcomes, including pre-eclampsia and childhood asthma. Current clinical guidelines for vitamin D supplementation in pregnancy are discussed in the context of the available evidence. The need for robust randomized controlled trials to address areas of existing uncertainty is highlighted.