AbstractBackgroundThe characteristics of allergic sensitization profiles can differ between populations and geographic regions, contributing differently to the association with allergic diseases. Consequently, the sensitization trajectories found in previous studies conducted in Northern Europe may not apply in Southern European countries.ObjectiveTo identify trajectories of allergic sensitization profiles during childhood and evaluate the association with allergic outcomes, using data from a Portuguese birth cohort.MethodsA random sample from Generation XXI was screened for allergic sensitization at 10 years of age. Among 452 allergic sensitized children, 186 were tested with ImmunoCAP^™ ISAC multiplex array that detects 112 molecular components, at three follow‐ups (4, 7, and 10 years old). Information on allergic outcomes (asthma, rhinitis, atopic dermatitis) was obtained at the 13‐year‐old follow‐up. Latent class analysis (LCA) was used to identify clusters of participants with similar sensitization profiles. Then, sensitization trajectories were defined based on the most prevalent transitions between clusters over time. Logistic regression was applied to estimate the association between sensitization trajectories and allergic diseases.ResultsFive trajectories were proposed: “no/few sensitizations,” “early persistent house dust mites (HDM),” “early HDM and persistent/late grass pollen,” “late grass pollen,” and “late HDM.” The “early HDM and persistent/late grass pollen” trajectory was associated with rhinitis and “early persistent HDM” with asthma and rhinitis.ConclusionDistinct sensitization trajectories pose different risks in the development of allergic diseases. These trajectories present some differences from those in Northern European countries and are important for planning adequate prevention health plans.