Babies Benefit from Moms’ Vitamin D Supplements

Most pregnant women strive to eat well to provide the best possible start for their growing infants. They may also take prenatal vitamins, which are often recommended. Moms’ vitamin D supplements offer numerous advantages. Now scientists suggest that higher doses may be even better.

Higher-Dose Vitamin D Supplements Boost Kids’ Brains

Danish researchers report that high doses of vitamin D3 starting around the sixth month of pregnancy were associated with better cognitive functioning in the children (JAMA Network Open, May 18, 2026). This placebo-controlled trial included over 600 mother-child pairs. The pregnant women were randomly assigned to get either a standard dose of 400 International Units daily of vitamin D3 or a high-dose of 2,400 IUs daily in addition to the baseline 400 IUs. The study was initially designed to study the effects of moms’ vitamin D supplements on asthma in the offspring. Women were enrolled between March 2009 and November 2010.

The investigators took advantage of this established study and administered neuropsychological tests  when the children reached 10 years of age. Kids exposed in utero to higher dose vitamin D scored better on tests of verbal and visual memory.

The authors note that,

“A growing body of research indicates that vitamin D supplementation during pregnancy is associated with multiple health benefits among offspring, including improved bone density,69 fewer fractures,69 and dental health. Given the cost and timeline required for large-scale trials, the present findings, together with existing evidence, support recommendations for increasing the dose of routine antenatal vitamin D supplementation.”

There are other studies of vitamin D during pregnancy and the outcomes for babies. Scientists have lots of evidence that people in northern latitudes have lower levels of vitamin D in the winter, when sunlight is not strong enough for the skin to make this hormone. How does that affect pregnant women and their infants? One study looked at the impact of moms’ vitamin D supplements on babies’ bone mineral density.

Moms’ Vitamin D Supplements Help Some Babies’ Bones

Wintertime babies have stronger bones if their mothers took vitamin D supplements during pregnancy. That’s according to a study of more than 1,000 pregnant women in the United Kingdom (The Lancet Diabetes & Endocrinology, May 2016).

In this double-blind, placebo-controlled trial, the women were randomly assigned to take either 1,000 International Units of vitamin D3 daily or a look-alike placebo. That was in addition to the 400 IUs that they were taking in their prenatal vitamins.

Difference Shows Up in Winter-Born Babies

There was no difference in the amount of bone mineral seen in babies in the study overall. There was, however, a significant difference when the scientists compared babies born in the winter. That is the season when mothers’ vitamin D levels naturally drop. Babies whose mothers took placebo had less bone mineral than those whose mothers had taken additional vitamin D supplements. This study was the first experiment to show that moms’ vitamin D supplements during pregnancy could improve babies’ bone mass.

Mothers’ Vitamin D Levels Affect Babies’ Dental Health

Here is one more study in favor of moms’ vitamin D supplements during pregnancy. Pregnant women with low levels of vitamin D circulating in their bloodstreams were more likely to have children with cavities in their baby teeth (Pediatrics, May 1, 2014). Researchers took blood samples from 207 Canadian women during their pregnancies.

When their infants were just over a year old, the scientists checked the babies’ teeth. Roughly one fourth of the 135 youngsters in the study had cavities. (Not all the women could be traced a year later.)

Mothers with the lowest levels of vitamin D were most likely to have babies with cavities. The scientists suggest that preventing vitamin D deficiency during pregnancy could pay off with healthier teeth for the offspring. The experts did not agree on whether supplements or sun exposure would be better for getting adequate vitamin D. For the low-income women in this study, moms’ vitamin D supplements might well be more practical than sun exposure, especially during the winter in Canada.

Learn More

We offer more details on vitamin D in our eGuide to Vitamin D and Optimal Health.  You can learn about symptoms of low vitamin D levels and how to test for that.