About a third of pregnant women in the US lack sufficient vitamin D to support healthy pregnancies

Recent research has revealed a fascinating connection between prenatal vitamin D levels and childhood cognitive development. A new peer-reviewed study published in the American Journal of Clinical Nutrition found that children whose mothers had higher vitamin D levels during pregnancy performed better on tests of memory, attention, and problem-solving skills between the ages of 7 to 12 compared to those whose mothers had lower levels.

While vitamin D has traditionally been associated with maintaining bone health, scientists have discovered its crucial role in regulating immune function, reducing inflammation, and protecting the nervous system. The study suggests that vitamin D may also play a significant role in supporting brain development starting in the womb.

The study indicated that the link between prenatal vitamin D levels and childhood cognition was particularly strong among Black families, who also experience higher rates of vitamin D deficiency. This highlights the potential for vitamin D supplementation to be a cost-effective strategy for enhancing brain development and reducing racial disparities.

By analyzing over 900 mother-child pairs across the U.S. who participated in the Environmental influences on Child Health Outcomes (ECHO) study, researchers measured vitamin D levels in the mothers’ blood during pregnancy and assessed children’s cognitive abilities using standardized tests. The study took into account various factors that influence childhood development, such as maternal education, neighborhood conditions, and the child’s age and sex.

These findings build upon previous research showing that higher vitamin D levels during pregnancy are linked to increased IQ in early childhood and reduced behavioral problems in middle childhood. The collective evidence suggests that vitamin D plays a crucial role in brain development during pregnancy, with long-lasting benefits for children’s cognitive and behavioral outcomes.

Why This Matters

Vitamin D deficiency is a widespread global issue, with approximately 42% of adults in the U.S. having vitamin D levels below the cutoff for deficiency. Among pregnant women, about a third are deficient, and the rates are even higher among Black pregnant women. This disparity is partly attributed to differences in skin pigmentation, as melanin pigment reduces the skin’s ability to produce vitamin D from sunlight.

While sunlight and certain foods provide vitamin D, supplementation is often necessary to meet the body’s requirements. Current guidelines recommend that pregnant women consume 600 international units (IU) of vitamin D daily, but higher doses are often needed to address deficiency. As many prenatal vitamins only provide around 400 IU, there is an opportunity for healthcare providers to improve screening and support around vitamin D supplementation before and during pregnancy.

If prenatal vitamin D supplementation can effectively support brain development, it could have enduring benefits for children. Studies have shown that higher cognitive scores in childhood are linked to improved memory, reasoning in older age, and even longer lifespan.

Remaining Questions

While the research suggests a correlation between higher prenatal vitamin D levels and improved cognitive and behavioral development in children, further studies are needed to establish a direct cause-and-effect relationship. Randomized controlled trials are essential to confirm these findings and determine the optimal target levels for vitamin D to support brain development during pregnancy.

The study, titled “Gestational vitamin D concentration and child cognitive development: a longitudinal cohort study in the Environmental influences on Child Health Outcomes Program,” was published in The American Journal of Clinical Nutrition in 2025.

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