According to the findings of a prospective cohort study published early online in the American Journal of Obstetrics and Gynecology, folic acid intake during the first trimester of pregnancy is not related to asthma in young offspring.
The authors note that there are conflicting results as to whether folic acid intake before and/or during pregnancy is associated with an increased risk of allergic disease in the offspring. They say that as the use of folic acid supplements to prevent neural tube defects is one of the most important neonatal advances reported in recent years, it is ‘important that it does not gain distrust on unsubstantiated scientific grounds’.
The purpose of their study was to assess the association of first trimester folic acid supplementation with asthma in the offspring at 6 years of age in a cohort of 1,499 US women with prospective information about folic acid intake during pregnancy. Around half of the women (51%) used folic acid in the month prior to conception and 88% in the third month of pregnancy. Logistic regression was used to assess the association between folic acid supplementation in pregnancy and asthma in the children, with the effect estimates expressed as odds ratios (ORs). The effect of supplementation was assessed for the continuous variable (per 100mcg increase in daily folic acid intake), and successively for the four categories of intake (no use; <400mcg, 400-800 mcg and >800 mcg daily use).
The adjusted OR per 100mcg increase in average intake of folic acid was 0.98 (95% CI: 0.93-1.04). For the different categories of daily folate intake, there was no evidence of any associations with childhood asthma and no evidence of any dose response relation for any time period (all p >0.05).
The authors conclude that their findings do not support any association of folic acid supplementation and asthma risk in offspring by the age of 6 years; however they say that further studies are needed to assess both the risk at doses higher than 800mcg in early pregnancy as well as the risk, at all doses, of folic acid supplementation in the second and third trimesters.