Prenatal exposure to air pollution and the risk of eczema in childhood: a systematic review and meta-analysis

An increasing number of studies investigated the association between air pollution during pregnancy and the risk of eczema in offspring. However, no meta-analysis has confirmed the existence and size of their association to date. We systematically searched PubMed, Web of Science, Cochrane Library, and Embase databases to select the observational controlled studies published from the inception date to October 16, 2021. Quality evaluation was guided by the Newcastle-Ottawa Scale (NOS). Sensitivity analysis was applied to assess the impact of each included study on the combined effects, and publication bias was examined by Begg's tests and Egger's tests. A total of 12 articles involving 69,374 participants met our eligibility criteria. A significant association between the maternal exposure to NO2 (per 10 mu g/m(3) increased) and childhood eczema was observed, with a pooled risk estimate of 1.13 (95% CI: 1.06-1.19), but no association was observed between exposure to PM10, PM2.5, and SO2 and the risk of eczema in offspring. Besides, the effect of maternal NO2 exposure on childhood eczema was significant in the first and second trimesters, but not in the third trimester. There was notable variability in geographic location (p = 0 .037) and air pollutant concentration (p = 0 .031) based on meta-regression. Our findings indicated that prenatal exposure to NO2 was a risk factor for elevated risk of eczema in childhood, especially in the first and second trimesters. Further studies with larger sample sizes considering different constituents of air pollution and various exposure windows are needed to validate these associations.