Vitamin D supplementation during pregnancy may be linked to better verbal and visual memory in children. Digest
Vitamin D plays a role in fetal brain development, but it remains unclear whether higher intake during pregnancy leads to measurable cognitive differences years later. A new study examined whether children's cognitive performance differed depending on their mothers' vitamin D dose during late pregnancy.
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The analysis used data from a Danish randomized trial in which 623 pregnant women had been assigned to different vitamin D doses. The researchers focused on 498 children whose mothers had received either the routine pregnancy dose recommended in Denmark of 400 IU of vitamin D3 per day or a higher dose of 2,800 IU of vitamin D3 per day, from pregnancy week 24 until one week after birth. At about age 10, the children took a series of cognitive tests that included measures of memory, attention, processing speed (how quickly they handled simple mental tasks), working memory (holding and using information briefly), executive function (skills such as planning and switching between tasks), and estimated intelligence. In their comparisons between the two groups, the researchers also accounted for the mothers' blood vitamin D levels before supplementation.
- Before supplementation, the typical blood 25-hydroxyvitamin D (25(OH)D) level was 30.3 ng/mL, and 15% of mothers had levels below 20 ng/mL. One week after birth, mothers had a typical 25(OH)D level of 27.5 ng/mL in the routine-dose group compared with 41.9 ng/mL in the higher-dose group.
- Children in the higher-dose group had modestly higher verbal and visual memory function scores than those in the routine-dose group.
- One executive function test initially looked better in the higher-dose group, but the difference was less convincing after more rigorous statistical testing.
- The findings did not suggest a broad cognitive advantage. Eight of the 11 cognitive functions tested were not clearly different between the two groups.
- Estimated intelligence was nearly identical: 107.6 in the higher-dose group versus 107.8 in the routine-dose group.
Vitamin D may influence how the developing brain builds and maintains neural circuits. It is thought to support the growth and maturation of nerve cells, chemical signaling between them, immune regulation, and protection from oxidative stress. Because different brain systems mature on different timelines, vitamin D exposure in late pregnancy may be more relevant to memory-related abilities than to broader cognitive functions. That could help explain why the clearest pattern appeared in memory rather than in estimated intelligence, attention, or processing speed.
A key limitation is that this was a later analysis of a trial originally designed for asthma, not cognition, so the memory findings should be treated as suggestive. Still, the results raise the possibility that prenatal vitamin D could influence specific aspects of later cognitive performance. In Aliquot #100, I discuss factors that influence child development before conception, during pregnancy and infancy, and into the toddler and early childhood years.