Children whose mothers received a higher dose of vitamin D during late pregnancy performed slightly better on tests of verbal and visual memory at age ten than children whose mothers received the standard dose. The differences were small, and the higher dose was not linked to better intelligence, attention, thinking speed, planning or working memory. A child’s vitamin D level after birth is influenced by sunlight, food and supplementation, as well as maternal factors such as breastfeeding, and maternal vitamin D status. For example, it is unclear whether the effects were caused by vitamin D exposure during pregnancy, after birth, or by vitamin D supplements taken during childhood up to the age of ten. The researchers found no convincing evidence that the higher dose worked differently according to the mother’s starting vitamin D level.