Prenatal folic acid supplementation improves long-term postnatal maternal cognitive performance: findings from a cohort study

Folic acid (FA) is a crucial component of the nervous system’s functions at all ages and is involved in a number of metabolic activities. We hypothesized that prenatal FA supplementation may profoundly affect women’s postnatal cognitive function, which has not been tested before. This study was based on a cohort study (GDM follow-up study, GFS), which is a sub-cohort study derived from Ma’anshan Birth Cohort Study (MABC). A total of 182 women who had prenatal FA supplementation information and completed postnatal cognitive function tests were included in this study. FA supplementation data were prospectively collected in the 1st /2nd /3rd trimester of pregnancy by questionnaires. Cognitive functions were assessed with Stroop Color-Word Test (SCWT), Digit Symbol Substitution Test (DSST) and Montreal Cognitive Assessment (MoCA) in-person interviews conducted by qualified investigators at postpartum follow-up (the mean duration of postpartum follow-up of 7.9 (± 0.4) years). The associations between prenatal FA supplementation at different periods, cumulative FA supplementation, and early postnatal cognitive performance were investigated using linear regression models. After adjusting for confounding factors, FA supplementation during the 1st trimester of pregnancy (β = 9.15, 95%CI: 2.67 ~ 15.62, p = 0.006) and entire pregnancy (β = 8.88, 95%CI: 1.61 ~ 16.15, p = 0.017) were significantly associated with higher DSST scores. Supplementation of FA one month prior pregnancy was significantly associated with shorter Stroop Test A time (β= -0.67, 95%CI: -1.30~-0.05, p = 0.035), Stroop Test A time/Correct number (β= -0.03, 95%CI: -0.05 ~ 0.00, p = 0.036), and Stroop Test B time (β= -0.87, 95%CI: -1.73~-0.01, p = 0.047). Supplementation of FA during the 3rd trimester of pregnancy was significantly linked to shorter Stroop Test B time/Correct number (β= -0.06, 95%CI: -0.12 ~ 0.00, p = 0.048). FA supplementation during the entire pregnancy was associated with shorter Stroop Test B time (β= -1.95, 95%CI: -3.53~-0.37, p = 0.016), Stroop Test B time/Correct number (β= -0.09, 95%CI: -0.15~-0.02, p = 0.014). Furthermore, cognitive function scores increases progressively with longer periods of prenatal FA supplementation. Our study is the first study suggested that FA supplementation from one month prior pregnancy to delivery could significantly improve maternal postpartum cognitive performance, and that the longer FA were taken, the greater benefit was likely to be.