Vitamin D Deficiency During Pregnancy May Impair Children's Cognitive Potential

Vitamin D deficiency during pregnancy is common and can harm a child's brain development. Research shows that mothers with adequate levels of this vitamin have children with better cognitive outcomes, especially among Black women, who are at higher risk of deficiency. Supplementation before or early in pregnancy can be essential to support learning and reduce inequalities in child development.

Vitamin D deficiency is one of the most common nutritional deficiencies worldwide. It is defined as the amount of vitamin D circulating in the blood below 20 nanograms per milliliter. This problem affects approximately one-third of all pregnant women in the United States.

Among some specific groups of pregnant women, the situation is even more serious: approximately 80% of Black women and almost half of those with family incomes below the poverty level are vitamin D deficient during pregnancy.

This deficiency is concerning because low levels of the vitamin during this delicate period can harm a child's brain development, leading to learning difficulties that can extend into adolescence.

Vitamin D deficiency during pregnancy can cause a variety of symptoms for the mother. Common symptoms include excessive fatigue, muscle and bone pain, and increased bone fragility, which increases the risk of osteoporosis and fractures. Hair loss, mood swings, and even depression may also occur.

During pregnancy, this deficiency is associated with significant complications such as high blood pressure (pre-eclampsia), gestational diabetes, and an increased risk of premature birth, making vitamin D essential for maternal health.

For the child, both in the womb and after birth, a deficiency can impair physical and brain development. Bones can become weaker, leading to diseases such as rickets, stunted growth, and increased tooth fragility. Muscle weakness and increased susceptibility to infections are also common, as vitamin D strengthens the immune system.

Furthermore, studies show that a deficiency of this vitamin can affect cognition, resulting in learning difficulties and lower academic performance later in life.

The human body has a specific receptor for vitamin D, called the vitamin D receptor, as well as an enzyme that converts the vitamin into its active form. Both the receptor and the enzyme are present in important brain cells, including neurons (the cells responsible for brain communication) and glial cells (which support and protect neurons).

When active vitamin D binds to the receptor in the fetal brain, it can control the activity of several genes involved in the formation of brain structure, the process of neuron differentiation, the regulation of chemicals that function as neurotransmitters, and the production of factors that stimulate the growth and survival of nerve cells.

Animal studies confirm that a lack of vitamin D during pregnancy can alter the shape and organization of the developing brain, in addition to disrupting fundamental cellular processes, such as cell multiplication and programmed cell death (a natural mechanism that eliminates defective cells).

Research in humans shows that vitamin D deficiency both early and late in pregnancy may be associated with future cognitive problems, suggesting its role throughout pregnancy. However, scientists are uncertain whether there is a specific critical period during which vitamin D has the greatest impact.

Some epidemiological studies, which follow large groups of people over time, have observed that higher vitamin D levels during pregnancy are linked to better cognitive development in the first years of life and also to higher intelligence quotient (IQ) in children between the ages of 4 and 7.

However, other studies have not found this association at slightly older ages, such as 7, 9, 10, or 14. One possible explanation is that, throughout childhood, other factors, such as stimulation received at home, the school environment, and the quality of family interactions, may more strongly influence a child's intellectual development, reducing the perception of the initial effects of vitamin D.

It is also possible that some studies have not detected true associations due to methodological limitations, such as the small number of participants, the lack of diversity in the study populations, or the fact that they measured vitamin D levels only at one point in pregnancy, usually late in pregnancy.

Given these shortcomings, further studies are needed, especially those that evaluate older children and include diverse populations. The present study aimed to investigate the relationship between vitamin D levels during pregnancy and different types of cognition (such as fluid intelligence, crystallized intelligence, and general cognitive performance) in children aged 7 to 12.

This work was conducted as part of a large program called "Environmental Influences on Child Health Outcomes" (ECHO). Furthermore, the researchers wanted to understand whether this relationship might vary according to the mother's race, since melanin, the pigment that gives skin color, reduces the ability to produce vitamin D through sun exposure.

Previous evidence suggests that Black people may have different responses to the effects of vitamin D, both in terms of bone health and other aspects of the body.

The study followed 912 mother-child pairs, approximately 37% from Black families and 52% from white families. Vitamin D levels were measured in the mothers' blood during pregnancy or in umbilical cord blood collected between the 4th and 42nd weeks of pregnancy, with a median around the 23rd week.

The children were assessed between the ages of 7 and 12 using a battery of cognitive tests developed by the United States National Institutes of Health. Statistical analyses took into account potential confounding factors, that is, other variables that could influence the results.

The results showed that the average vitamin D level in pregnant women was 23.8 nanograms per milliliter. Each 10-unit increase in this value was associated with better general cognition and fluid intelligence scores, although it showed no significant impact on crystallized intelligence.

When the data were analyzed separately by race, it was observed that the association appeared to be stronger among children of Black mothers, with greater gains in fluid cognition, than among children of non-Black mothers.

Another important finding was that early pregnancy may be a particularly sensitive period, as the greatest difference in vitamin D levels was observed at this stage when comparing mothers of children with better and worse cognitive performance.

In conclusion, the study showed that adequate vitamin D levels during pregnancy are associated with better cognitive performance in childhood, especially in children of Black mothers.

Given that these women are at higher risk of deficiency, ensuring adequate vitamin D levels before or early in pregnancy may be a key strategy for promoting healthier brain development while reducing racial inequalities in children's cognitive outcomes.

READ MORE:

Gestational vitamin D concentration and child cognitive development: a longitudinal cohort study in the Environmental influences on Child Health Outcomes Program

Melissa M. Melough, Monica McGrath, Meredith Palmore, Brent R. Collett, Jean M. Kerver, Christine W. Hockett, Rebecca J. Schmidt, Rachel S. Kelly, Kristen Lyall, Qi Zhao, Alison E. Hipwell, Susan A. Korrick, Diane Gilbert-Diamond, Scott T. Weiss, Su H. Chu, Hooman Mirzakhani, Jennifer M. Porter, and Sheela Sathyanarayana for the ECHO Cohort Consortium

The American Journal of Clinical Nutrition. Volume 122, Issue 2, August 2025, Pages 571-581

https://doi.org/10.1016/j.ajcnut.2025.06.017

Abstract: 

Low vitamin D concentrations are common—especially among those with darker pigmented skin—and are frequently observed during pregnancy. Given its important role in brain development, inadequate gestational vitamin D may impair child cognitive development. We aimed to evaluate associations of gestational vitamin D concentrations with childhood cognitive scores, explore whether this relationship differs by self-reported race, and examine sensitive exposure windows within pregnancy. This prospective cohort study included 912 mother–child dyads (37.3% Black, 52.3% White) from the Environmental influences on Child Health Outcomes program. 25-hydroxyvitamin D [25(OH)D] concentrations were measured in prenatal or cord blood collected between 4 and 42 wk gestation (median: 23 wk). Children’s cognition was assessed at ages 7–12 y using the NIH Toolbox Cognition Battery. Relationships of 25(OH)D and cognitive scores were examined using mixed-effects linear models adjusted for confounders. Potential sensitive periods were explored by estimating population 25(OH)D patterns across gestation for varying levels of the cognitive outcomes. Mean gestational 25(OH)D was 23.8 ng/mL (SD: 10.0 ng/mL). Each 10-ng/mL increase was associated with greater overall (β: 1.11; 95% CI: 0.08, 2.14) and fluid cognition scores (β: 1.21; 95% CI: 0.07, 2.34), but not crystallized cognition. Although these associations were not significantly modified by self-reported race, associations appeared stronger in children of Black mothers (β: 2.99; 95% CI: 0.82, 5.16) than those in non-Black mothers (β: 0.43; 95% CI: −0.93, 1.78) for fluid cognition. Early pregnancy may be a critical exposure period, evidenced by the greatest divergence in the pattern of 25(OH)D during this period between the mothers of children in the 90th and those in the 10th percentiles of cognitive outcomes. Gestational 25(OH)D concentrations were positively associated with cognitive scores, especially in children of Black mothers. Given higher deficiency risk among Black women, vitamin D repletion before or in early pregnancy may be an important strategy for reducing racial disparities in child neurodevelopment.