Prevalence of hypovitaminosis D in Western populations is high; pregnant women are identified as a high-risk group, especially if dark skinned. Consequences of severe clinical vitamin D deficiency in pregnancy can be life threatening to the newborn, while lesser degrees of hypovitaminosis D may have important long-term implications for offspring health. Past experiences with routine provision of 10 microg/d (400 IU/d) to all pregnant mothers suggest that this dose is sufficient to prevent overt neonatal complications of vitamin D deficiency. Recent data suggest that supplementation with dosages above 10 microg/d may be required for optimal health in the mother and child; however, further research is required for the assessment of the benefits and safety of supplementation with higher dosages. Lack of unified advice on vitamin D supplementation of pregnant mothers in the UK hinders the implementation of primary prevention strategies and is likely to leave some deficient mothers without supplementation.