Vitamin D supplementation of pregnant women could lead to longlasting reduction in osteoporotic fractures in their children, according to a study published in this week's issue of The Lancet. The study shows that children whose mothers were lacking in vitamin D during pregnancy grow up to have weaker bones.

Vitamin D insufficiency is common in women of childbearing age. Professor Cyrus Cooper (MRC Epidemiology Resource Centre, Southampton General Hospital, UK) and colleagues studied 198 children born in 1991-92. The body build, nutrition, and vitamin D supplementation of their mothers were measured during pregnancy. The children were then followed up at age 9 years to relate these maternal characteristics to their body size and bone mass.

Women who took vitamin D supplements and women who were exposed to higher levels of sunshine in pregnancy were less likely to be deficient in vitamin D. Sunlight helps the body to make its own vitamin D. Giving women supplements of vitamin D, particularly if they are pregnant during the winter months when sunlight levels are low, should help their children's bones grow stronger.

Professor Cooper states: "These findings provide evidence that maternal vitamin D status during pregnancy influences the bone growth of the offspring, and their risk of osteoporosis in later life. The results add to a large body of evidence that intrauterine and early postnatal development contributes to bone mineral accrual and thereby osteoporosis risk; they also point to preventive strategies which now require evaluation in randomised controlled trials." (quote by e-mail, does not appear in published paper)