Cesarean delivery is associated with atopic sensitization to inhalants but not food at age 5

Abstract Purpose Intrauterine and early neonatal exposures, including maternal, obstetric, and postnatal factors, may influence the risk of atopic sensitization in offspring. However, their independent associations with inhalant and food sensitization remain underexplored. Methods In the prospective Kuopio Birth Cohort, allergen-specific serum immunoglobulin E (IgE) levels for six food and eight inhalant allergens were measured in 619 children aged 5 years. Atopic sensitization was defined as IgE ≥ 0.70 kU/L. Information on maternal, obstetric, neonatal, breastfeeding, and environmental factors was collected from questionnaires and hospital records. Results Overall, 31.3% of children were sensitized, including 22.9% to inhalant and 18.7% to food allergens. Lower maternal weight was associated with higher odds of any sensitization, inhalant sensitization, and food sensitization. Maternal smoking was associated with increased odds of any sensitization, whereas twin pregnancy was associated with reduced odds. Cesarean delivery increased the odds of inhalant sensitization by 1.7–1.9-fold but was not associated with food sensitization. Keeping cats indoors during pregnancy was linked to a 50% lower risk of any sensitization and inhalant sensitization. By contrast, maternal pregestational diabetes and hypertension showed stronger associations with increased odds of food allergen sensitization. Other maternal and perinatal factors showed no significant associations. Conclusion Prenatal and perinatal factors may differentially influence sensitization to inhalant and food allergens, with cesarean delivery and early-life cat exposure being associated primarily with inhalant sensitization.