Maternal Folate Intake during Pregnancy and Childhood Asthma in a Population‐based Cohort

American Journal of Respiratory and Critical Care Medicine
Q1
Jan 2017
Citations:50
Influential Citations:2
Observational Studies (Human)
83
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Methods
Population-based prospective cohort (Norwegian Mother and Child Cohort Study, MoBa) in Norway; included children born 2002–2006 with asthma outcomes assessed at age 7; asthma defined via Norwegian Prescription Database (n=39,846; 1,901 cases) or maternal report (n=28,872; 1,624 cases); maternal total folate intake estimated from a food-frequency questionnaire around 22 weeks gestation; maternal plasma folate measured in a subsample; analyses used log-binomial and multinomial logistic regression with robust variance; follow-up through 2014; covariates adjusted for and missing data handled with multiple imputation.
Intervention
Daily oral folic acid–containing supplements during pregnancy at or above the WHO-recommended dose of 400 mg/day; median supplement intake among users ~500 mg/day (range 400–600 mg/day); duration: throughout pregnancy.
Results
Total folate intake during pregnancy from foods and supplements was associated with higher asthma risk at age 7. Highest vs lowest quintile: adjusted relative risk 1.23 (95% CI 1.06–1.44) for prescription-defined asthma; similar results for maternal-report asthma. Among current asthma cases at age 7, 45% also had atopy; highest vs lowest quintile showed 33% higher risk for asthma without atopy and 51% higher risk for asthma with atopy. Conclusion: high total folate intake during pregnancy, resulting from folic acid supplementation at or above the recommended dose plus a folate-rich diet, is linked to a small increased risk of childhood asthma, particularly at the highest intake level.
Limitations
Observational design; potential residual confounding; outcome classification based on prescription data or maternal report rather than clinical examination; possible misclassification of atopy; folate intake estimated by FFQ with measurement error; plasma folate data available only in a small subsample; generalizability may be limited to populations with different folate fortification practices.

Abstract

Rationale: A potential adverse effect of high folate intake during pregnancy on children's asthma development remains controversial. Objectives: To prospectively investigate folate intake from both food and supplements during pregnancy and asthma at ...