Vitamins in pregnancy are usually discussed in terms of a baby’s health at birth. But could the amount of vitamin D taken during pregnancy also influence how a child’s brain works many years later?

A recent Danish study suggests that it might. 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 findings are intriguing, but they need to be kept in perspective. The differences were small, and the higher dose was not linked to better intelligence, attention, thinking speed, planning or working memory. The researchers also did not examine whether the memory differences affected schoolwork or daily life.

The study followed children whose mothers had taken part in a randomised trial originally designed to determine whether high-dose vitamin D supplementation during pregnancy reduced the risk of persistent wheeze and asthma in offspring. From the 24th week of pregnancy until one week after birth, one group received 2,800 international units (IU), or 70 micrograms, of vitamin D each day. The other received the standard Danish dose of 400 IU, or 10 micrograms.

Of the 623 children in the original trial, 498 returned for cognitive testing at around ten years old. After accounting for factors that might have influenced the results, the researchers found that children in the higher-dose group performed slightly better at recalling words and objects and remembering where visual patterns had........

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