Folic acid in pregnancy Is there a link with childhood asthma or wheeze?

Background Folic acid supplementation has an established role in early pregnancy for preventing neural tube defects. However, there is controversy over a possible link between late pregnancy folic acid supplementation and childhood asthma. Objective To review the evidence exploring the association between maternal folate exposure in pregnancy and childhood asthma or wheeze. Results Four relevant observational studies were identified. Two found statistically significant associations between childhood asthma and late (but not early) pregnancy maternal folic acid exposure. Another found a statistically significant association between childhood wheeze and early (but not late) pregnancy maternal folk acid exposure. A fourth study found little association between maternal dietary folate in pregnancy and infantile wheeze. Discussion The currently available evidence regarding an association between folate in pregnancy and childhood asthma or wheeze is conflicting. We offer suggestions for discussing the potential risk with patients and recommend further research on this subject be conducted.