Pregnancy Vitamin D Levels May Influence a Child’s Future IQ

A growing body of research continues to highlight the importance of vitamin D during pregnancy—not just for bone health, but also for a child’s developing brain. A recent study adds new evidence suggesting that a mother’s vitamin D level during pregnancy may play a meaningful role in her child’s later IQ.

Vitamin D is essential for healthy fetal development, including the formation of neurons and other structures that support long-term cognitive function. Earlier studies have found associations between low gestational vitamin D and increased risks of neurodevelopmental concerns, including conditions such as autism and schizophrenia. Some research has also pointed toward links between prenatal vitamin D levels and children’s IQ, though not all studies have agreed.

This new study analyzed vitamin D status—measured as 25-hydroxyvitamin D [25(OH)D]—in 1,503 women during their second trimester and compared those levels with their children’s cognitive scores between ages 4 and 6. Researchers used Stanford-Binet IQ assessments and adjusted for multiple factors using a multivariable statistical model.

The findings were striking:
• 46% of pregnant participants were vitamin D deficient, with normal levels generally considered to be above 20 ng/mL.
• Vitamin D levels varied by skin pigmentation, largely because melanin naturally reduces the skin’s ability to produce vitamin D from sunlight.
• Despite these variations, the relationship between vitamin D and IQ was consistent across all skin tones.

For every 10 ng/mL increase in maternal vitamin D, children scored:
• 1.17 points higher on Full Scale IQ
• 1.17 points higher on Verbal IQ
• 1.03 points higher on Nonverbal IQ

These differences may seem modest individually, but across a population they represent a meaningful shift in early cognitive development.

What This Means for Expecting Mothers
The researchers concluded that vitamin D status during pregnancy may be an important—and modifiable—factor in supporting a child’s neurocognitive development. Because vitamin D deficiency is common, especially in individuals with darker skin or limited sun exposure, screening and supplementation could make a real difference.

For expecting mothers, this study reinforces a simple but important message: Ensuring adequate vitamin D during pregnancy may support your baby’s brain development for years to come. As always, any supplementation should be discussed with a qualified healthcare provider, as vitamin D needs vary from person to person.