Folic acid in pregnancy and psychomotor development

Folic acid is an essential vitamin, proven to prevent neural tube defects, and it can therefore only be a good thing to take lots of it in pregnancy – right? Well, not necessarily, if we are to believe the findings of a Spanish observational cohort study (Valera-Gran D et al. JAMA Pediatr. 2014; doi:10.1001/jamapediatrics.2014.2611). Over 2200 pregnant women were recruited from four diverse areas of Spain, and their offspring's developmental status was assessed using standard Bayley Scales at between 1 and 2 years. Data on folic acid consumption, both dietary and as supplements, were gathered by questionnaires completed during pregnancy, but serum levels were not measured. They found a significantly lower mean psychomotor scale score (difference −4.35 points; 95% CI, −8.34 to −0.36) in children whose mothers took supplement dosages higher than 5000 μg/day, compared to those who took the recommended dose of 400–1000 μg/day. In multivariate analysis they attempted to control for measurable confounding factors, such as social class differences and low birth weight, and the association persisted. There was significant variation between the four different sites. The authors cite some animal evidence that high intakes of manufactured as opposed to dietary …