Insights into Allergic Risk Factors from Birth Cohort Studies.

Hossenbaccus, Lubnaa; Linton, Sophia; Ramchandani, Rashi; Gallant, Mallory; Ellis, Anne K

OBJECTIVE To present an update of birth cohort study designs and their contributions to allergic risk. DATA SOURCES The PubMed database was used to search for relevant articles. STUDY Selections Peer-reviewed prospective and retrospective studies involving the assessment of allergy using human birth cohorts between 2014-2021 were examined. RESULTS Parental history of allergic diseases, especially in cases involving both parents, is associated with increased risk of allergy. Exposure to prenatal and postnatal smoking and limited diet diversity were associated with increased allergic burden. The impact of early life infections and antibiotics on disease development may be associated with the onset of asthma, though this remains debated. Cohort studies also revealed that the mode of delivery and breastfeeding duration impacts the odds ratio of asthma and eczema development. Household exposures, including pets, house dust mites, and scented aeroallergens may confer protective effects, while high air pollution exposure and low socioeconomic status may be risk-enhancing. Exposure to antibiotics during early-life may be associated with increased asthma risk while viral infections may lead to disease protection, though the impact of the coronavirus disease 2019 (COVID-19) pandemic on allergic risk is yet to be understood. CONCLUSION While assessing risk of allergic disease development is complex, clinicians can apply these insights on the multi-factorial nature of atopy to better understand and potentially mitigate disease development.