Vitamin D during pregnancy ‘strengthen winter baby’s bones’

A study by the University of Southampton recruited over 1,000 pregnant women who took either 1000 units of vitamin D every day or a matched placebo capsule from 14 week’s gestation until delivery of the baby.

Results showed that the dose of vitamin D was highly effective at increasing vitamin D levels in the mother. More than 80% of women who had received the supplement had satisfactory levels of vitamin D late in pregnancy, when most calcium bone mineral is transferred from mother to baby, compared to 35% in the placebo group.

Although babies born in the study showed no difference in bone mass between mothers who took the supplement compared to those who took the placebo there was one interesting difference.

Babies born during the winter months, to mothers who took vitamin D, had greater bone mass than winter babies born to mothers who received the placebo.

Professor Nicholas Harvey, Professor of Rheumatology and Clinical Epidemiology at the MRC Lifecourse Epidemiology Unit, University of Southampton, added: "Babies’ bones strengthen during the last stages of pregnancy. Since sunlight is our most important source of vitamin D, mothers’ levels of vitamin D tend to drop from summer to winter, and babies born in the winter months tend to have lower bone density than those born during the summer. The MAVIDOS Trial has given us the first evidence that supplementing mothers with vitamin D during pregnancy counteracts the seasonal drop in maternal vitamin D levels and may help to ensure good bone development in these winter births."

Image: Rowen Hall having a DXA scan. Photo: Courtesy of The University of Southampton