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.
To review the evidence exploring the association between maternal folate exposure in pregnancy and childhood asthma or wheeze.
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 folic acid exposure. A fourth study found little association between maternal dietary folate in pregnancy and infantile wheeze.
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.
Folate is a water soluble B vitamin that must be obtained in the diet or through supplementation. For more than 50 years it has been known that folate plays an integral role in embryonic development.1 Periconceptional folic acid in doses of at least 0.36 mg has been shown to prevent approximately 72% of neural tube defects,2,3 and therefore a daily dose of 0.4 mg is widely recommended for all women at average risk from at least 1 month preconception to 12 weeks pregnancy.4 Despite this, many Australian women do not have sufficient folate intake in pregnancy,5 thus mandatory folic acid fortification of flour was introduced in Australia in September 2009.6
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