Pollen exposures in pregnancy and early life are associated with childhood asthma incidence

Background: Pollen exposure is an environmental risk factor for asthma symptoms and allergic reactions in children. The extent to which pollen exposure in pregnancy and the first year of life influences the development of childhood asthma and rhinitis is not fully understood. Objective: We aimed to investigate early life exposures to pollen with childhood asthma and rhinitis at age 6 in a longitudinal birth cohort of the United Kingdom. Methods: In this retrospective cohort study, via logistic regressions, we analyzed the associations between pollen exposures in pregnancy and the first year of life with childhood asthma and rhinitis. Results: Higher pollen exposure accumulated during pregnancy and during the first year of life both associated with an increased odds of asthma at age 6 (OR = 1.14, 95% CI 1.03-1.26, p = 0.01; OR = 1.15, 95% CI 1.03-1.29, p = 0.02, respectively). We did not observe statistically significant associations between early life pollen exposures and the odds of rhinitis at the same age. Conclusion: High pollen exposure during early life (prenatal and postnatal) associated with an increased risk of asthma incidence at age 6. Further studies are desired to validate these findings and to elucidate the mechanisms of early life exposures to pollen on asthma etiology.