Vitamin D supplements during pregnancy may result in stronger bones in babies born in winter according to a new study by the University of Southampton.
Researchers from the MRC Lifecourse Epidemiology Unit at the University of Southampton recruited over 1000 pregnant women across Southampton, Oxford and Sheffield to a randomised, double-blind, placebo controlled trial of vitamin D supplements in pregnancy.
Women were chosen at random to take either 1000 units (25 microgrammes) of vitamin D every day or a matched placebo capsule from 14 weeks gestation until delivery of the baby.
Analysis showed that the babies born during winter to mother who had taken the supplement had greater bone mass than the winter babies born to mothers who took the placebo.
Nicholas Harvey, professor of rheumatology and clinical epidemiology at teh MRC Lifecourse Epidemiology Unit said: '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 trial has given us the first evidence that supplementing mothers with vitamin D during pregnancy removes the seasonal drop in maternal vitamin D levels and may help to ensure good bone development in these winter births.'
More than 80% of women who received the supplement had satisfactory levels of vitamin D when measured in late pregnancy. Analysis of all the babies born in the study showed there was no difference in bone mass between mothers who took the supplement and those who didn't.
The study was funded by the charity Arthritis Research UK, with further funding support from the Medical Research Council, National Institute for Health Research and the Bupa Foundation and has been published in the Lancet Diabetes and Endocrinology.