Vitamin D is recognized as critical for the neurological development of fetuses, however it is unclear whether gestational vitamin D levels have an impact on the IQ of children.  Although some data suggests language skills are impaired in those children of mothers with lower vitamin D status, that work was only conducted with children up to 2 years of age.  Melough and colleagues conducted a study to extend those observations into older children and they present their outcomes in a paper published in the January 2021 issue of The Journal of Nutrition.  Because deficiency of vitamin D occurs more frequently in women with darker skin tones, which occurs because the color reduces cutaneous synthesis, the authors also evaluated the impact of race on the outcomes.

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Data for these analyses were obtained from the CANDLE study (Conditions Affecting Neurocognitive Development and Learning in Early Childhood).  Subjects (n=1019 women) were in their second trimester of pregnancy, delivered the child no earlier than 34 weeks of gestation, and provided blood samples for 25(OH)D analyses.  The children underwent IQ testing at 4-6 years of age.

Deficiency of vitamin D occurred in 45.6% of women and levels were 19.8 ng/mL in Black and 25.9 ng/mL in White participants.  Increased maternal vitamin D levels were associated with elevated Full Scale IQ, Verbal IQ, and Nonverbal IQ, but there were no differences in the results caused by race.  These observations led the authors to conclude that maternal vitamin D levels in the second trimester may predict neurocognitive development, and thus child IQ at 4-6 years of age.


Melough MM, Murphy LE, Graff JC, Derefinko KJ, LeWinn KZ, Bush NR, 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, Volume 151, Issue 1, January 2021, Pages 132–139,

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