Women who lack vitamin D when pregnant may end up with fatter children, a Southampton University study has shown.
Children of women with low blood levels of vitamin D were leaner at birth, researchers found. But by the age of six they were 6% to 8% fatter than children whose mothers had a healthy intake of vitamin D.
The findings, from a study of 977 women and their children, were reported in the American Journal of Clinical Nutrition.
Study leader Dr Sian Robinson, from the University of Southampton, said: ''In the context of current concerns about low vitamin D status in young women, and increasing rates of childhood obesity in the UK, we need to understand more about the long-term health consequences for children who are born to mothers who have low vitamin D status.
''Although there is growing evidence that vitamin D status is linked to body fatness in children and adults, this research now suggests that the mother's status in pregnancy could be important too.
''An interpretation of our data is that there could be programmed effects on the foetus arising from a lack of maternal vitamin D that remain with the baby and predispose him or her to gain excess body fat in later childhood. Although further studies are needed, our findings add weight to current concerns about the prevalence of low vitamin D status among women of reproductive age.''
Women are recommended to take an additional 10 micrograms per day of vitamin D during pregnancy, but the advice is not always followed.
The study is part of a wider investigation by the Medical Research Council Lifecourse Epidemiology Unit, which is looking at the long term effects on children of environmental factors in pregnancy.
Professor Cyrus Cooper, the unit's director, said: ''The observations that maternal vitamin D insufficiency might be associated with reduced size at birth, but accelerated gain in body fat during early childhood, add to the considerable amount of evidence suggesting that vitamin D status during pregnancy may have critical effects on the later health of offspring.''