Research paper
Prenatal folic acid and risk of asthma in children: a systematic review and meta-analysis.
Study answer
What this study found
Periconceptional folic acid supplementation was not associated with an increased risk of childhood asthma. The pooled estimate for asthma was RR 1.01 (95% CI 0.78, 1.30), and when asthma and wheeze were combined the RR was 1.05 (95% CI 1.02, 1.09). Excluding one influential study changed the combined estimate to RR 1.04 (95% CI 0.92, 1.17). The authors concluded that more research is needed because of heterogeneity in exposures and outcomes and the limited number of studies, especially for non-asthma allergic outcomes.
- Study & population
- Systematic review and meta-analysis of observational cohort and nested case-control studies from multiple countries; no randomized trials were identified.
- Intervention
- Exposure was periconceptional or first-trimester folic acid-containing supplement use, generally around 400-500 mg/d where reported, versus no folic acid use.
- Key limitation
- Evidence came entirely from observational studies, so residual confounding and exposure misclassification remain possible.
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Open PDFOriginal abstract
BACKGROUND Childhood asthma has become a critical public health problem because of its high morbidity and increasing prevalence. The impact of nutrition and other exposures during pregnancy on long-term health and development of children has been of …