Periconceptional folic acid supplementation and risk of parent-reported asthma in children at 4-6 years of age.

backgroundFolic acid supplementation is universally recommended for women of child-bearing age to prevent fetal neural tube defects (NTDs). Concerns have arisen over the potential risk for childhood allergy and asthma due to folic acid supplementation. We examined whether periconceptional supplementation with low-dose folic acid only was associated with an increased risk for allergy symptoms or asthma in offspring at 4-6 years of age.

methodsOut of 247 831 participating women enrolled in 1993-1996, 9090 were randomly selected and their children were followed up in 2000-2001. Information on mothers' demographic characteristics, folic acid supplementation and allergic diseases among children was collected. We used logistic regression to evaluate the association between folic acid intake and risk for allergic disease while adjusting for potential confounding factors.

resultsThe rate of allergy symptoms was 1.54% among children whose mothers had taken folic acid compared with 2.04% among those whose mothers had not taken folic acid, and the rate of asthma was 0.92% and 0.88%, respectively. Maternal folic acid supplementation was not associated with risk for allergy symptoms or asthma, with odds ratios (95% CI) of 0.80 (0.58-1.11) and 1.04 (0.67-1.61), respectively. No differences in the occurrence of allergy symptoms or asthma were observed when data were analysed by timing of supplementation or compliance with folic acid supplementation.

conclusionsSupplementation with low-dose folic acid only during the periconceptional period did not increase risk for allergy symptoms or asthma in children at 4-6 years of age in a population without staple fortification with folic acid.