Giving seven times more vitamin D during pregnancy improves children’s memory at age 10. The problem is in the fine print

A Danish follow-up of a randomized pregnancy trial re-tested 498 children at age 10.

Children whose mothers took 2,800 IU of vitamin D daily from week 24 of pregnancy showed modestly better verbal and visual memory than those whose mothers took 400 IU.

IQ did not differ between groups.

The findings suggest a possible small long-term cognitive benefit, but the result is secondary and not strong enough to change routine prenatal guidance.