Children are more likely to be chubbier if their mother had low levels of vitamin D during pregnancy, a British study suggests.

Children of women with low blood levels of vitamin D were leaner at birth, researchers found. But by the time they reached age six, those children had more body fat than those born to women with higher vitamin D status during pregnancy.

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There are concerns about the prevalence of low vitamin D status among women of reproductive age, researchers say. (Erik de Castro/Reuters)

"In the context of current concerns about low vitamin D status in young women, and increasing rates of childhood obesity …we need to understand more about the long-term health consequences for children who are born to mothers who have low vitamin D status," Dr. Siân Robinson, who led the study at the University of Southampton, said in a release Wednesday.

"An interpretation of our data is that there could be programmed effects on the fetus 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."

The study published in the American Journal of Clinical Nutrition looked at 977 women and their children. The women had their vitamin D levels sampled at 34 weeks gestation.

Seasonal difference

The children had their heights and weights measured and their body composition checked using pediatric scanners called DXA within three weeks of birth and at ages four and six.

When the researchers modeled potential influences of the sunshine vitamin levels in pregnancy, they found among women who had samples taken in the summer, 84 per cent had higher concentrations compared with 23 per cent for those whose samples were taken in the winter and spring.

The study's authors said taking vitamin D supplements in late pregnancy was the second most important predictor. In the UK, women are advised to take 10 micrograms of vitamin D in pregnancy.

The analysis also took factors such as maternal height, age, number of children, education, smoking and vitamin D intake from food and supplements into consideration.

The researchers said the use of DXA is well validated in adults but that newborns and young children differ in their bone mineral content and tend to move more during the measurements, which could affect accuracy.

They speculated that that there may be different routes to higher fat levels in childhood that are associated with both insufficient and excessive nutrition in pregnancy.

The study was funded by the Medical Research Council, British Heart Foundation, Food Standards Agency and Arthritis Research UK. The research was part of a wider investigation by the Medical Research Council's epidemiology unit, which is looking at the long-term effects on children of environmental factors in pregnancy.

One of the authors has received speaking fees and research funding from multinational food companies.