What we Already Know Vitamin D forms from sunlight on the skin and is used by the body to absorb calcium, needed for healthy bones and teeth. Up to half of all pregnant women in the UK are deficient, which is more common in winter than in summer. Vitamin D deficiency disproportionately affects black and minority ethnic groups, those who cover their skin, those who are overweight and those with chronic illness, and particular care should be taken to advise these women (National Institute for Health and Care Excellence, 2019). Pregnant women who are deficient (blood serum level <50nm) are more likely to have pregnancy complications including pre-eclampsia, diabetes, preterm birth and small babies. Babies born deficient may have affected bone growth or in severe cases rickets (flexible bones). Deficiency has also been linked with the development of childhood allergy (European Food Safety Authority, 2016; Royal College of Obstetricians & …