High-dose vitamin D3 supplementation during pregnancy is associated with better cognitive function in offspring at 10 years of age, particularly visual and verbal memory and cognitive flexibility, according to a post hoc analysis of the Copenhagen Prospective Studies on Asthma in Childhood 2010.
Globally, vitamin D deficiency is a widespread problem among pregnant women. Vitamin D plays a role in foetal brain development during pregnancy, and in vitro and animal models highlight its involvement in key neurodevelopmental processes, such as neuronal differentiation, neurotransmitter synthesis, intracellular calcium signalling, and antioxidant activity, said the researchers.
This analysis involved 623 pregnant women who were randomly assigned to receive either a higher dose (2,400 IU/d) of vitamin D3 or a placebo in addition to the standard dose (400 IU/d) of vitamin D3 from the 24th week of pregnancy until 1 week postpartum.
A cohort of 498 children (mean age 10.3 years, 51.8 percent boys) born to mothers exposed to either a high-dose (n=247) or a standard-dose (n=251) vitamin D3 underwent assessment of cognitive function across domains, including intelligence, processing speed, reaction time, attention, motor function, memory, working memory, and executive functions using a neurocognitive test battery.
During the 10-year visit, offspring of mothers who received high-dose vitamin D3 had significantly higher scores in verbal (ẞ=0.17; p=0.02), visual (ẞ=0.24; p=0.01), and cognitive flexibility or set shift (ẞ=0.19; p=0.04) than those who received a standard dose. [JAMA Netw Open 2026;doi:10.1001/jamanetworkopen.2026.11464]
However, no significant differences were observed between the high- and low-dose vitamin D3 groups in the remaining cognitive functions.
The researchers noted that although a prior analysis of this RCT found no significant effect of prenatal vitamin D3 supplementation on cognition at 2.5 years, their current 10-year findings indicate that the association between vitamin D3 supplementation and certain cognitive functions may become measurable later in childhood.
“Overall, we found that high-dose supplementation was positively associated with three of the 11 functions assessed: verbal memory, visual memory, and cognitive flexibility or set shifting. However, the association with cognitive flexibility or set shifting was not significant after correction for multiple testing,” said the researchers.
“These findings support the hypothesis that prenatal vitamin D3 exposure may be positively associated with a subset of cognitive functions in childhood,” they added.