Children born to women who had low levels of vitamin D during their pregnancy are more likely to have language problems, a new study suggests.

Insufficient levels of vitamin D during pregnancy have been linked to some health problems in children and animal offspring.

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Our vitamin D levels fluctuate depending on exposure to sunlight and diet. (iStock)

Vitamin D insufficiency has been seen in up to 60 per cent of Caucasian women, with higher rates estimated for those with darker skin, researchers say.

In Monday's issue of the journal Pediatrics, Australian researchers said they found that mothers who had the lowest vitamin D levels in their blood during their second trimester had almost double the risk of their babies developing language problems.

The study focused on 743 Caucasian children who were measured on behaviour checklists starting at age two and scored on vocabulary tests starting at age five. Just over half the children, 412, were followed to age 17.

Supplements suggested during pregnancy

"This study found that vitamin D insufficiency among Caucasian women during pregnancy was associated with an increased rate of language impairment among offspring," Prue Hart of the University of Western Australia and her co-authors concluded.

"Maternal supplementation during pregnancy may reduce the risk of developmental language difficulties."

The findings suggest a trend toward lower vitamin D levels among women of reproductive age also has important implications for public health.

The developing fetus relies on mom's vitamin D stores, so the circulating levels 18 weeks into pregnancy offer an accurate measure of the baby's exposure during the second and third trimesters, the researchers said.

Lab studies suggest that vitamin D is fundamental to neurodevelopment, which was reflected in the language scores.

The near doubling in risk of language problems for the children of women with insufficient levels of vitamin D held after taking  the mothers' age, smoking during pregnancy and the number of children into account.

Strengths of the study included a large number of participants and long followup period. The length also introduced a drawback in that not all of the participants had the language test at age 17, although the researcher said behavioural and language abilities are generally stable from middle childhood onward.

The researchers did not find an association between vitamin D levels in pregnancy and behavioural or emotional problems.

The study was funded by Australia's National Health and Medical Research Council and the Telethon Institute for Child Health Research.