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Wise et al.

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Author Manuscript Author Manuscript Author Manuscript Author Manuscript TABLE VI.B-2. Evidence for the effects of pollen allergen exposure (in utero and early childhood exposure) on the development of allergic rhinitis Study Year LOE Study design Study groups Type of exposure Conclusion b Erbas et al. 481 2013 2b Prospective birth cohort 620 children (6–7 years old) from MACS RCT (with at least 1 first-degree family member with a history of eczema, asthma, hay fever, severe food allergy) Pollen exposure a during infancy (at 3– 6 months) Risk factor for hay fever (OR 1.1; 95% CI, 1.01– 1.3) Kihlström et al. 519 2002 3b Cross-sectional 583 children with atopic heredity (4–5 years old) High-dose exposure to birch pollen at 0–3 months No association with allergic rhinoconjunctivitis (OR 1.0; 95% CI, 0.6–1.8) High-dose exposure to birch pollen at 1 year No association with allergic rhinoconjunctivitis (OR 1.3; 95% CI, 0.8–2.2)

a Defined as birth “inside” or “outside” the pollen season and by measuring daily 24-hour average pollen concentrations for grass and others (which include trees, weeds, and herbs). b ORs are adjusted and reported with 95% CIs in parentheses. CI = confidence interval; LOE = level of evidence; MACS = Melbourne Atopy Cohort Study; OR = odds ratio; RCT = randomized controlled trial.

Int Forum Allergy Rhinol . Author manuscript; available in PMC 2020 June 10.