JAMA Netw Open
High-dose vitamin D in pregnancy tied to sharper childhood cognition
Clinical Takeaway: Higher-dose prenatal vitamin D3 may offer modest childhood cognitive benefits years later, particularly for memory.
Vitamin D deficiency in pregnancy is common, with observational data hinting at links to childhood cognition. But randomized evidence on whether higher-dose pregnancy supplementation actually shifts cognitive outcomes in children has been scarce. This post hoc analysis of a Danish trial tested whether children whose mothers took 2800 IU daily in late pregnancy performed differently on a neuropsychological battery at age 10 than those whose mothers took 400 IU.
High-dose vitamin D exposure was positively associated with verbal and visual memory, among 498 children assessed. Of the remaining cognitive functions tested, including intelligence, mental flexibility, processing speed, attention, and planning, none differed significantly between groups.
The signal persisted when analyses were restricted to children without an ADHD diagnosis, suggesting the memory finding is not driven by neurodevelopmental disorder status. The study is a post hoc secondary analysis of the COPSAC2010 trial, which was originally designed to test whether prenatal vitamin D3 reduced childhood wheeze or asthma.
Pregnant women were randomized at week 24 to either 2800 IU or 400 IU daily through one week postpartum. Cognitive testing at age 10 covered 11 functions across eight domains.
Prior analyses of the same cohort linked high-dose prenatal vitamin D3 to improved bone mineralization, fewer childhood fractures, and better dental outcomes.
"These findings strengthen evidence on the association of prenatal vitamin D exposure with childhood cognition," the authors conclude. They add that the cost and timeline required for large-scale trials mean accumulated evidence from existing cohorts can help to provide evidence about increasing the routine antenatal dose.
Source: Frederiksen OF. JAMA Netw Open. 2026 May 18. High-dose vitamin D3 supplementation during pregnancy and test-based cognitive performance at age 10 years