Summary: Higher maternal vitamin D levels during pregnancy were associated with higher IQ scores in children at ages 4–6.
Source: Seattle Children’s
Vitamin D is a vital nutrient with multiple roles in the body, including contributions to brain development. A mother’s vitamin D status during pregnancy influences the amount transferred to the fetus and may affect neurodevelopmental outcomes in childhood.
A new analysis published in The Journal of Nutrition found that higher maternal vitamin D levels in pregnancy were associated with higher IQ scores in children at ages 4 to 6. The study also highlighted notably lower vitamin D concentrations among Black pregnant women compared with White pregnant women.
Melissa Melough, lead author and research scientist in the Department of Child Health, Behavior, and Development at Seattle Children’s Research Institute, notes that vitamin D deficiency is common in the general population and among pregnant women, and that Black women are disproportionately affected. She hopes the research will encourage clinicians to recognize and address disparities in vitamin D status for those at higher risk.
“Melanin pigment protects the skin from UV damage, but it also reduces skin production of vitamin D. Given this, the high rates of vitamin D deficiency we observed among Black pregnant women were not surprising,” Melough said. “Although many pregnant women take prenatal vitamins, standard prenatal formulations may not always correct an existing vitamin D deficiency.”
Addressing disparities
Melough and colleagues report that a substantial share of Black pregnant women in the U.S. may be vitamin D deficient. In the cohort they analyzed, about 46% of mothers had vitamin D levels classified as deficient during pregnancy, and average levels were lower in Black women than in White women.
The researchers used data from the CANDLE (Conditions Affecting Neurocognitive Development and Learning in Early Childhood) study, a Tennessee-based cohort that began recruiting pregnant women in 2006 and followed participants and their children over time to assess health and development.
After accounting for several other factors that influence IQ, the investigators found a positive association between maternal vitamin D measured in the second trimester and child IQ scores at ages 4–6. While this observational study cannot establish causation, the results suggest that prenatal vitamin D status may have meaningful implications for children’s neurocognitive development and merit further investigation.
Vitamin D deficiency and practical steps
“Vitamin D deficiency is common,” Melough said. “The encouraging news is that it can often be addressed. It is difficult to obtain enough vitamin D from diet alone, and not everyone can reliably produce vitamin D from sun exposure, so supplementation is a practical option for many people.”
Current recommendations typically list 600 international units (IU) per day as the target for most adults, but average dietary intake in the U.S. is often well below that level. Typical food sources with meaningful vitamin D content include fatty fish, eggs, and fortified products such as milk and some breakfast cereals. Because dietary intake alone is frequently insufficient, supplementation and attention to risk factors for deficiency are key considerations during pregnancy.
Additional research is needed to define optimal vitamin D targets during pregnancy, but the study’s authors suggest that identifying and correcting deficiency—particularly among Black women and others at high risk—could be an important strategy to reduce health disparities and support cognitive development in offspring.
Key takeaways
Three main points from the study:
- Vitamin D deficiency is common in pregnancy; people with darker skin pigmentation, including many Black women, are at higher risk because melanin reduces skin production of vitamin D.
- Higher maternal vitamin D levels in pregnancy were associated with modestly higher IQ scores in children at ages 4–6, suggesting a potential role for prenatal vitamin D in supporting neurodevelopment.
- Targeted screening and nutritional supplementation for those at high risk of deficiency may help correct deficits and could support cognitive outcomes in children.
“I want people to know that vitamin D deficiency is common and can influence children’s development,” Melough said. “Deficiency can occur even with a generally healthy diet and may relate to lifestyle, skin pigmentation, or other factors beyond an individual’s control.”
About this neurodevelopment research news
Source: Seattle Children’s
Contact: Kathryn Mueller – Seattle Children’s
Image: The image is in the public domain
Original Research: Closed access. “Maternal Plasma 25-Hydroxyvitamin D during Gestation Is Positively Associated with Neurocognitive Development in Offspring at Age 4–6 Years” by Melissa Melough et al., Journal of Nutrition
Abstract
Maternal Plasma 25-Hydroxyvitamin D during Gestation Is Positively Associated with Neurocognitive Development in Offspring at Age 4–6 Years
Background
Vitamin D plays a role in embryonic neuronal differentiation and other developmental processes that can influence later neurocognitive function. Prior observational studies have reported inconsistent findings regarding gestational vitamin D and child neurodevelopment.
Objectives
This study evaluated the association between gestational 25-hydroxyvitamin D [25(OH)D] and children’s IQ at 4–6 years and examined whether associations varied by race.
Methods
Researchers used data from the CANDLE cohort. Between 2006 and 2011, CANDLE enrolled 1,503 women in the second trimester of healthy singleton pregnancies. The analysis included participants with gestation ≥34 weeks and available 25(OH)D and IQ data. Associations between second-trimester 25(OH)D concentrations and Stanford-Binet IQ scores at age 4–6 were examined using multivariable linear regression, with interaction terms to explore effect modification by race.
Results
Among 1,019 eligible mother–child pairs, mean 25(OH)D concentration was 21.6 ± 8.4 ng/mL, measured at a mean gestational age of 23.0 ± 3.0 weeks. Vitamin D deficiency (25[OH]D < 20 ng/mL) was present in 45.6% of participants. Mean 25(OH)D differed by race (19.8 ± 7.2 ng/mL in Black participants vs. 25.9 ± 9.3 ng/mL in White participants; P < 0.001). In adjusted analyses, each 10-ng/mL increase in 25(OH)D was associated with a 1.17-point higher Full Scale IQ (95% CI: 0.27, 2.06), a 1.17-point higher Verbal IQ (95% CI: 0.19, 2.15), and a 1.03-point higher Nonverbal IQ (95% CI: 0.10, 1.95). No evidence of effect modification by race was observed.
Conclusions
Second-trimester maternal 25(OH)D was positively associated with IQ at ages 4–6, suggesting that maternal vitamin D status during pregnancy may be an important predictor of neurocognitive development. These findings may inform prenatal nutrition guidance and are particularly relevant for Black and other dark-skinned women who face higher risk of vitamin D deficiency.