A study of 1,800 mother-infant pairs evaluated the blood levels of vitamin D in pregnant women and then looked at the mental scores of their babies at 14 months of age. The babies of mothers who had a vitamin D level greater than 30 ng/mL during their pregnancy had significantly higher scores on the mental and psychomotor scales of a commonly used developmental assessment test.
This study conducted in Spain shows another remarkable effect of maintaining adequate vitamin D levels during pregnancy. Other studies have shown significant benefits for immune function in infants whose mothers have a vitamin D level of at least 70 ng/mL.
I recommend that all pregnant women have their blood tested during early pregnancy and take enough vitamin D to raise their levels to at least 70 ng/mL. This may require supplementation in the range of 5,000-10,000 IU of vitamin D each day.
Morales E, Guxens M, Llop S, et al. Circulating 25-Hydroxyvitamin D3 in Pregnancy and Infant Neuropsychological Development. Pediatrics. 2012 Sep 17.