Linking anemia to asthma: maternal, childhood and adult perspectives from a meta-analysis of 20 studies.

Background: Anemia has been implicated as a potential risk factor for asthma across different life stages, yet evidence remains inconsistent.

Objective: This meta-analysis (CRD420251008733) aimed to evaluate the associations between maternal anemia and offspring asthma, childhood anemia and asthma, and adult anemia and asthma.

Methods: We searched PubMed, Embase, Web of Science, and Cochrane Library, identifying 20 observational studies. Study quality was assessed using the Newcastle-Ottawa Scale (NOS) and Agency for Healthcare Research and Quality (AHRQ) checklist. Heterogeneity, sensitivity, and publication bias were explored through subgroup analyses, sensitivity tests, and Egger's test. Meta-analysis performed using Stata 17.

Results: Twenty studies involving over 4499364 participants were included. The results showed pooled OR for the association between anemia and asthma (OR = 1.55, 95% CI: 1.36-1.77). Maternal anemia during pregnancy was associated with a modest increase in offspring asthma risk (OR = 1.19, 95% CI: 1.02-1.38), adult anemia was also linked to asthma (OR = 1.94, 95% CI: 1.14-3.30). Childhood anemia showed a stronger association with asthma (OR = 2.22, 95% CI: 1.65-2.99), though Egger's test (p = 0.041) suggested publication bias, with an adjusted OR of 2.03 (95% CI: 1.51-2.74).

Conclusions: Anemia is significantly associated with an increased risk of asthma, particularly in children. These findings suggest a potential role for anemia screening in asthma management.