Folic acid during pregnancy and cognition during childhood Original paper

The Centers for Disease Control and Prevention recommends that individuals who are planning to become pregnant take 400 micrograms (μg) of folic acid daily to prevent neural tube (related to the brain and spine) defects. The tolerable upper intake level (the highest level of nutrient intake likely to pose no risk of adverse health effects for most people) for folic acid is 1,000 μg per day, based on the potential for high-dose folic acid to mask a vitamin B₁₂ deficiency.

Some evidence suggests that supplementation with 400–1,000 μg of folic acid during pregnancy is also associated with improved cognition during childhood, whereas <400 or ≥1,000 μg may adversely affect child cognition. However, more research was needed to examine these associations.

This longitudinal study assessed the association between both low (<400 μg/day) and high (≥1000 μg/day) doses of a folic acid supplement during pregnancy and cognitive function in children. A total of 1,609 mothers in Spain completed two food frequency questionnaires during pregnancy: at weeks 10–13 to assess their reported folic acid use from 3 months preconception to the third month of pregnancy (the periconceptional period), and at weeks 28–32 to assess folic acid supplement use from months 4–7 of pregnancy (the second trimester). Folic acid dosage was categorized as <400, 400–999, or ≥1000 μg/day. The children completed working memory and attentional function assessments between ages 7 and 9.

The authors of the analysis adjusted for a number of factors, such as maternal age, energy intake, parental BMI, sex, and age.

Compared with the children of mothers who took 400–999 μg/day of folic acid, the children of mothers who took <400 μg/day during the second trimester had lower levels of alertness.

When adjusted for the child’s sex, taking <400 μg/day of folic acid during the second trimester was associated with lower levels of alertness in girls and lower working memory in boys. In addition, taking ≥1,000 μg/day before conception through the second trimester combined was associated with higher levels of attentional function (concentration) and working memory in girls.