Vitamin D in Pregnancy Could Reduce Baby's MS Risk

New research shows that the 'sunshine vitamin' has more benefits for baby before birth than previously thought, including reducing risk of multiple sclerosis (MS).

Vitamin D in Pregnancy Could Reduce Baby's MS Risk Ivanko80/Shutterstock

The benefits of taking vitamin D supplements in pregnancy, especially during the winter, are stacking up. First, we recently reported that the "sunshine vitamin" has been shown to help boost baby's bone growth. Now, a new study published in the journal JAMA Neurology may give pregnant women another reason to pop those vitamins: a reduced risk of their children developing the disease multiple sclerosis (MS).

How vitamin D affects MS

Researchers used a bit of detective work to identify young adults diagnosed with MS using the Finnish Hospital Discharge Register, and matched them to mothers who were part of the Finnish Maternity Cohort, data collected on thousands of pregnant women in Finland dating back to 1983. The scientists identified 176 cases of MS in the children of those women, and compared them to 326 controls. "We measured their vitamin D status and found that children born to women who were vitamin D deficient during the pregnancy were 90 percent more likely to develop MS as an adult than children born to women who were not vitamin D deficient," study author Kassandra Munger, Sc.D., of the Harvard T.H. Chan School of Public Health, tells Fit Pregnancy. "This is the first study to show this relationship."

The connection between vitamin D and MS isn't totally understood, but research has shown that a lack of the vitamin is linked to MS in adults. In MS, the immune system attacks the central nervous system, damaging nerve fibers and interrupting the signals nerves send to the brain. Vitamin D, whose main role was long thought to be in bone health, has recently been discovered to play a part in immune health as well. "How vitamin D affects the risk of MS is not known," Munger says. "We do know that vitamin D affects immune system function, and that vitamin D can shift the immune system away from the response seen in MS."

Given what is already known, it makes sense that a lack of vitamin D in the womb could affect a child's risk for developing MS later in life. Seventy percent of the women in this study were in their first trimester when their levels were checked, and 99 percent were earlier than 28 weeks. So, it seems that even early in pregnancy, vitamin D deficiency can have negative consequences.

Should you supplement?

So far, the American College of Obstetricians and Gynecologists has held off on recommending pregnant women take more than the 400 IU contained in prenatal vitamins, although it notes that 1,000-2,000 are safe. Munger says women should consult their OB before taking more than what's in their prenatal. "I would advise that pregnant women talk with their doctors regarding their vitamin D status and whether supplementation beyond the vitamin D in a prenatal vitamin is warranted," she says. "It is premature to recommend women take a specific dose of vitamin D for the purpose of reducing the risk of MS in her child. Much more research is needed."

Because we absorb most of our vitamin D from the sun, pregnant women should check with their doctor to make sure they are getting enough in the winter months. (Interestingly, the study points out that many MS patients have spring birthdays.) And although this study did not focus on vitamin D after birth, the American Academy of Pediatrics advises that all infants, whether they are breastfed or formula fed, take a vitamin D supplement to ensure their levels are high enough.

In addition, Munger says there are a couple of other things pregnant women can do to reduce their baby's chances of developing MS. "We also know that cigarette smoking and obesity increase MS risk," she says. "Therefore, women can avoid smoking and maintain a healthy body weight, and encourage these behaviors in their children, to possibly reduce their MS risk."