Higher Vitamin D Levels during Pregnancy are Linked to Higher IQ in Five to Six Year-Old Offspring

by | Feb 2, 2021 | 2021, Infant and Children's Health, Pregnancy and Lactation, Vitamin D - Recommended Levels

Written by Joyce Smith, BS. This study finds that maternal 25(OH)D during pregnancy is positively associated with children’s neurocognitive development through ages four to six.

pregnancyVitamin D deficiency is prevalent within the general population worldwide and is problematic for   women of reproductive age, particularly for women with darker skin 1. Also vulnerable are children born to mothers with low maternal vitamin D levels, and while a positive association has linked gestational vitamin D levels with developmental brain disorders including autism 2, not all studies 3 have validated an association between gestational vitamin D and offspring IQ.

The CANDLE (Conditions Affecting Neurocognitive Development and Learning in Early Childhood) study is a prospective pregnancy cohort study designed to examine biological and environmental influences on early childhood neurocognitive development 4. Tylavsky and colleagues, in a previous CANDLE study of predominantly black women found that maternal 25(OH)D was positively associated with language development in two year old offspring 5. Building on that study, the team investigated whether the association would persist through ages four to six 6. They recruited 1,503 pregnant women at 16 and 28 weeks of gestation between December 2006 and July 2011. The women provided self-reported demographics, socio-economic data, and food frequency questionnaires, as well as blood samples at baseline (16-18 weeks gestation) for vitamin D blood levels. Offspring IQ assessment was done at 4-6 years of age. Primary outcome was the full scale IQ scores (FSIQ); secondary outcomes were the verbal (VIQ) and non-verbal (NVIQ) scores.

Mean concentration of 25(OH)D in the 1,019 mothers and 4-6 year old children pairs was 21.6 ±8.4 ng/mL. Vitamin D deficiency of ≤ 25(OH)D ng/mL was present in 45.6% of women and was more prevalent in Blacks than in Whites [± SD of 19.8 ± 7.2 ng/mL vs. 25.9 ± 9.3 ng/mL (P<0.001]. Researchers suggest that white women were more likely to experience socioeconomic advantages including higher educational attainment, greater income, and higher diet quality. Maternal 25(OH)D during pregnancy was positively associated with children’s FSIQ, VIQ, and NVIQ at age 4–6 years. After adjusting for social and economic factors they found that a 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 points), a 1.17-point higher Verbal IQ (95% CI: 0.19, 2.15 points), and a 1.03-point higher Nonverbal IQ (95% CI: 0.10, 1.95 points).

While the associations between 25(OH) D concentrations and offspring IQ were similar between races, the authors suggest these findings are particularly relevant for Black women who are at higher risk of vitamin D deficiency because of their lower skin melanin content. Study results highlight the importance of assessing and addressing vitamin D deficiencies in women. Randomized controlled trials have suggested that daily supplementation of 800to 1000 IU 7 may be needed to restore levels in pregnancy, and that doses as high as 4000 IU may be ideal in cases of severe deficiency 8. Vitamin D is an inexpensive and modifiable factor, which can through screening and nutritional intervention support the more vulnerable black population.

Researchers did not examine the genetic profile of the study participants and recommend that future studies investigate the several known single-nucleotide polymorphisms in vitamin D pathway genes 9 that could potentially modify the outcome of an association between gestational vitamin D levels and offspring cognition. Future studies are recommended.

Source: Melough, Melissa M., Laura E. Murphy, J. Carolyn Graff, Karen J. Derefinko, Kaja Z. LeWinn, Nicole R. Bush, Daniel A. Enquobahrie et al. “Maternal Plasma 25-Hydroxyvitamin D during Gestation Is Positively Associated with Neurocognitive Development in Offspring at Age 4–6 Years.” The Journal of Nutrition 151, no. 1 (2021): 132-139.

© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society for Nutrition. All rights reserved.

Posted February 2, 2021.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

References:

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