Pregnant women who take vitamin D could guarantee their babies have stronger bones as they grow up, a study has claimed.
Researchers from Southampton General hospital found in a study of 198 mothers that women who took vitamin D supplements or were exposed to large amounts of sunlight - which helps the body produce the vitamin - had children with stronger bones.
Mothers who lacked the vitamin, which is vital for absorption of bone-strengthening calcium, had children whose bones were weaker at the age of nine.
Lead author of the study, professor Cyrus Cooper, said: "These findings produce evidence that maternal vitamin D status during pregnancy influences the bone growth of the offspring, and their risk of osteoporosis later in 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 preventative strategies which now require evaluation in randomised control trials."
The team, who published their findings in medical journal the Lancet, measured the level of vitamin D in women's blood in the late stages of pregnancy and looked at the levels of calcium in the babies' umbilical cord blood.
After nine years, the researchers traced 198 of the original group of 596 and measured the mineral content and bone mineral density of the children.
Professor Cooper now wants to carry out further studies to see whether giving supplements to women deficient in vitamin D could help boost the strength of their babies' bones later in life.