Folic Acid Late in Pregnancy May Increase Risk of Asthma Among Children

The findings of a new study suggest that side effects of folic acid used during late pregnancy may increase the risk of asthma in young children.

The results of the study, published in the American Journal of Epidemiology, suggest that expecting mothers should be careful in striking a balance in their intake of folic acid, which is crucial in early pregnancy to prevent birth defects such as spina bifida and anencephaly. But researchers say that the study points to the importance of targeting the use of folic acid only during the first trimester, and then backing off of the supplements later.

Currently, it is recommended that women take about 400 micrograms of folic acid daily before conception and during the first trimester of pregnancy to prevent neural tube defects. However, many pregnant women continue to take supplements loaded with folic acid throughout their pregnancy.

Researchers from the University of Adelaide in Australia conducted a birth cohort study from 1998 to 2005, and found that children were 1.26 times more likely to develop childhood asthma at 3.5 years old if their mother took folic acid supplements in late pregnancy. The study found that in most cases, the mother took folic acid as part of a multivitamin.

Researchers did not find a connection between an intake of folates, a natural form of folic acid, through diet. Folate is present in beans, lentils, orange juice, peanuts and green vegetables.

“Our findings related to timing and sources of folate in pregnancy have important implications for recommendations about optimal folate intake in pregnancy,” researchers concluded. “Our findings are in agreement with current recommendations pre- and in early pregnancy. However, they highlight the need to consider current supplementation strategies so as to maximize the neuroprotective effects of folic acid while minimizing potential adverse postnatal respiratory effects. We acknowledge the need for further studies replicating our findings before any specific recommendations against folic acid supplementation in late pregnancy can be made.”