Maternal folic acid supplementation before and during early pregnancy has a well-established association with reduced neural tube development risks in a child, but few studies have examined possible benefits in its continuation past the first trimester, and even fewer have gathered evidence that was not observational in nature.
 
In a recent clinical trial, a team of researchers investigated maternal folic acid supplementation throughout the entire pregnancy, versus controls, in order to determine possible additional cognitive benefits in the children of these pregnancies.
 
“Emerging evidence shows that the period of rapid growth and development of the fetal brain occurring in later pregnancy is particularly sensitive to maternal folate concentrations,” the authors of the study said. “Also, myelination of the brain, which is most intensive from mid-gestation to the second year of life and essential for cognitive development as it protects nerve axons and facilitates communication between neurons, may be particularly vulnerable to deficiency of folate.”
 
The researchers followed up with 11-year-old children of women in Northern Ireland who took part in the randomized trial of Folic Acid Supplementation in the Second and Third Trimesters (FASSTT) study during pregnancy, at which time they received 400 nanograms/day of folic acid, or a placebo, from the 14^th gestational week. In total, 68 children from the 119 mother-child pairs in the initial study were evaluated.
 
Cognitive performance was assessed using the Wechsler Intelligence Scale for Children, which includes metrics related to full scale intelligence quotient, verbal comprehension, working memory, perceptual reasoning, and processing speed. Neuronal function was then assessed using MEG brain imaging.
 
 Compared to the children of mothers who took a placebo, those who were in the folic acid group scored significantly higher in two processing speed tests, namely the symbol search and cancellation tests. Verbal comprehension improvements were only significant in girls.
 
MEG assessment of neuronal responses to a language task showed increased power at the Beta and High Gamma bands in children from FA-supplemented mothers, which the researchers said suggested more efficient semantic processing of language.
 
The authors of the study concluded, based on both observational and neurological evidence, that continued folic acid supplementation, beyond the early period currently recommended to prevent neural tube defects, can benefit the neurocognitive development of a child.
 
“Our results, reporting the third follow-up of mother-child pairs from the FASSTT trial, show that the 11-year-old children of mothers randomized to FA compared with placebo during trimesters 2 and 3 of pregnancy scored significantly higher in specified cognitive IQ domains of the WISC-IV assessment, namely, two Processing Speed tests, i.e. symbol search (by 2.9 points) and cancellation (by 11.3 points), and Verbal Comprehension (by 6.5 points) in girls,” the authors concluded. “In addition to using standardized IQ tests to measure child cognition, we applied magnetoencephalographic brain imaging for the first time in a study of this kind, and the findings not only reinforce our previous findings of cognitive benefits in these children at 3 and 7 years but provide new evidence of a specific role of prenatal FA in semantic processing of language. The totality of evidence has important impacts in informing new policy and clinical practice in relation to FA use in pregnancy.”