MONDAY, Feb. 13 (HealthDay News) -- Pregnant women with low levels of vitamin D may be putting their children at risk for language difficulties, Australian researchers report.

Taking vitamin D supplements during pregnancy may relieve the problem, they suggest.

"Adequate vitamin D levels among pregnant women may be important for the optimal development of their baby," said lead researcher Andrew Whitehouse, an associate professor and reader in developmental psychopathology at the Telethon Institute for Child Health Research at the University of Western Australia. "However, it is important for the findings of this study to be replicated before any strong conclusions are made."

Vitamin D levels among pregnant women have decreased steadily over the past 20 years, most likely because of less exposure to sunlight, Whitehouse said.

"The effects of lower maternal vitamin D levels on the developing offspring is not fully understood," he said. "The current study found that women with vitamin D insufficiency during pregnancy have an increased risk of having a child with developmental language difficulties."

The report was published in the Feb. 13 online edition of Pediatrics.

For the study, Whitehouse's team looked at vitamin D levels in more than 700 pregnant women. They also measured their children's behavior at ages 2, 5, 8, 10, 14 and 17.

In addition, the researchers measured language development when the children were ages 5 and 10.

The researchers found that vitamin D levels during pregnancy had no effect on behavioral or emotional problems of the children.

However, there were significant differences in language development among children whose mothers had low levels of vitamin D during pregnancy.

Language difficulties increased twofold for children whose mothers had the lowest level of vitamin D, compared with children whose mothers had normal levels of vitamin D, Whitehouse's group found.

"The findings suggest that there may be a link between maternal vitamin D levels during pregnancy and offspring neurodevelopment," Whitehouse said.

However, while the study uncovered an association between the expectant mothers' vitamin D levels and their children's language development, it did not prove a cause-and-effect relationship.

"If vitamin D insufficiency during prenatal life is a cause of childhood language difficulties -- and this still needs to be determined conclusively -- then vitamin D supplementation of pregnant women may be an important next step," he said.

Dr. Jennifer Wu, an obstetrician/gynecologist at Lenox Hill Hospital in New York City, thinks that vitamin D is important for pregnant women.

"Women should get their vitamin D levels checked. We would like to correct these deficiencies before pregnancy," she said.

"Luckily, most [pregnant] women are on a prenatal vitamin and it contains 1,200 international units (IU) of vitamin D, so most women are supplemented throughout pregnancy," Wu added.

Women who are deficient in vitamin D may need as much as 10,000 IU a day, she said.

"If you are starting to try to get pregnant, you should start your prenatal vitamin," Wu said. "It has a lot of good things in it that will be onboard when you get pregnant."

Another expert, Dr. Michael F. Holick, a professor of medicine, physiology and biophysics at Boston University School of Medicine, noted that vitamin D deficiency increases the risk for preeclampsia (a condition marked by increased blood pressure and protein in the urine during pregnancy) and the need for a cesarean delivery.

"So, I am not surprised that developmental issues are also a concern for fetuses that are developing in a vitamin D-deficient state," he said.

"Pregnant women should be increasing their vitamin D intake to levels recommended by the Endocrine Society, which is 1,500 to 2,000 IU a day," Holick said.

More information

For more on vitamin D, visit the U.S. National Institutes of Health.

SOURCES: Andrew Whitehouse, Ph.D., associate professor and reader, developmental psychopathology, Telethon Institute for Child Health Research, University of Western Australia; Michael F. Holick, M.D., Ph.D., professor, medicine, physiology and biophysics, Boston University School of Medicine; Jennifer Wu, M.D., obstetrician/gynecologist, Lenox Hill Hospital, New York City; Feb. 13, 2012, Pediatrics, online

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