A longitudinal study on the association between maternal serum 25 (OH)-vitamin D concentrations during a critical window of fetal neurodevelopment and behavioral, emotional, and language outcomes of offspring recently published in the Official Journal of the American Academy of Pediatrics links low serum vitamin D levels of women during pregnancy with learning disabilities in their children. The study was conducted in Perth, Western Australia on a total of 743 Caucasian women and their children over a period of 17 years. Mothers who had serum vitamin D levels <46 nmol/L during pregnancy are twice as liikely to have a child with a language impairment than moms who had vitamin D levels higher than 70 nmol/L.
According to Lisa Bodnar, a professor at the University of Pittsburgh, who was not involved with the study, “While the results do not prove that low vitamin D is to blame for later problems, they point to a very plausible association that warrants more attention.” Vitamin D is crucial for fetal development, but “the effects of lower maternal vitamin D levels on the developing offspring is not fully understood,” said the lead author of the study, Andrew Whitehouse.
Whitehouse also stated that earlier studies have shown some links between low vitamin D during pregnancy and pediatric problems such as weaker bones, asthma, and short stature.
He and his colleagues in Perth, Western Australia conducted this long-term study to determine whether vitamin D levels in the moms might have actually influence later behavioral and language development in their children.
Two decades ago, they measured the vitamin D levels of more than 700 women who were about half-way through their pregnancy. They tested the children of these moms to measure their behavioral and emotional development and language skills at ages 2, 5, 8, 10, 14, and 17 years.
The moms were split into four groups — from lowest to highest vitamin D levels; researchers found that the risk of having a kid with emotional or behavioral issues was the same for each group. Although maternal vitamin D status was not shown to be linked with behavioral or emotional problems in children, it was clearly linked with language learning skills.
Mothers with the lowest serum vitamin D levels had between 15 and 46 nanomoles per liter (nmol/L) in their blood, while those with the highest serum vitamin D levels had 72 to 154 nmol/L. According to current guidelines, levels of vitamin D are not considered deficient unless they are below 30 nmol/L. When the researchers looked at language skills, the team found that mothers with vitamin D levels below 46 nmol/L were more likely to have a child with a language impairment than mothers in the highest vitamin D category.
The language impairments were determined from scores on the Peabody Picture Vocabulary Test. About 18 percent of moms with low serum vitamin D had a child with a language learning impairment at age 10, compared to only eight percent of the moms with the highest serum evels of vitamin D.
According to study author Andrew Whitehouse:
“The logical thought is that maternal Vitamin D insufficiency during pregnancy is affecting the normal course of brain development. 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.”
It is important to note that correlation does NOT equal causation. Just because low serum vitamin D status is linked with learning disabilities in children, it does not mean that it is the cause of learning disabilities in children. Women with low serum vitamin D status also tend to be overweight, and being overweight is also associated with developmental delays and cognitive impairments in children. It may also be likely that poor diet and lack of physical activity in mothers are the main underlying causes in childhood developmental delays, because poor diet, lack of physical activity, obesity, and low vitamin D status are all factors that occur together.
The Institute of Medicine recommends that pregnant women get 600 international units (IUs) of vitamin D per day, but more recent studies on vitamin D during pregnancy suggest that 4,000 IUs of vitamin D per day are optimal for prevention of complications during pregnancy as well as childhood diseases such as asthma and diabetes.
Aside from supplementation, you can boost your vitamin D status by consuming nutrient-rich superfoods that have been traditionally recommended for women of childbearing age for centuries. These foods include liver (from organically grown, grass-fed animals), egg yolks (from pasture-raised hens if possible), uncooked dairy products, salmon, sardines, and cod liver oil.
You can decrease your risk of having a child with learning disabilities by testing your serum vitamin D status before getting pregnant, optimizing your serum vitamin D to at least 72 nmol/L, making sure you are not overweight, getting an adequate amount of exercise and sleep, spending time in the sun each day without the use of sunblock, and eating a healthy diet that includes organ meats, egg yolks, unpasteurized dairy, fish, and cod liver oil.