Smoke exposure and childhood atopic eczema and food allergy: A systematic review and meta‐analysis

Abstract

BackgroundThere is no consensus on the effect of timing and type of smoke exposure on early allergy development. This study aimed to determine the relationship between early eczema or food allergy/hypersensitivity development in children by firstly investigating the effect of smoke exposure across critical development periods and secondly by analyzing effects of parental atcive or passive smoking.MethodsFour databases (PubMed, Web of Science, Scopus and Embase) were searched in May 2022 and assessed by two independent reviewers. Case–control, cross‐sectional or cohort studies reporting on smoke exposure from preconception to postnatal periods and atopic eczema, food allergy and/or hypersensitivity outcomes by age 3 years were included. The Newcastle–Ottawa Scale was used to assess study quality. Random effects model was used to estimate the pooled risk ratios.ResultsFrom 1689 identified records, 32 studies with nearly 190,000 subjects were included. Parental smoking during preconception, pregnancy and postnatal periods was generally not associated with the risk of eczema, food allergy and food sensitisation development by age 3 years. Maternal active smoking during pregnancy was negatively associated with self‐reported doctor diagnosis of eczema (RR = 0.87, 95% CI 0.77–0.98; I2 = 50.56) and maternal passive smoking during pregnancy was positively associated with clinician assessment of eczema in one study (RR = 1.38; 95% CI 1.06–1.79).ConclusionOur findings highlighted the importance of in utero programming in early‐life allergy development. Despite the weak evidence, our results suggest pregnant women should minimise their contact with second‐hand smoke to prevent offspring eczema development. There is a need for greater utilisation of objective allergy assessments in future studies.

Nurturing Infants to Prevent Atopic Dermatitis and Food Allergies: A Longitudinal Study

“…Smoking has previously been recognized as a contributing factor to DNA methylation when offspring are exposed to it before birth [ 29 , 30 , 31 ]. As a result, a hypothesis suggests in-utero programming in early-life allergy development, which has been recently supported by a meta-analysis [ 32 ], which suggests smoking cessation for pregnant women and emphasizes the importance of avoiding secondhand smoke to prevent the development of AD [ 3 ].…”