Background & aimsUltra-processed foods (UPF) consumption has been associated with unhealthy outcomes. However, the literature lacks robust longitudinal studies considering its cumulative effect, particularly in young populations. This study aimed to evaluate the relationship between UPF consumption patterns throughout childhood with growth and adiposity trajectories. MethodsGeneration XXI population-based birth cohort (Porto, Portugal) participants were included. Food frequency questionnaire items at 4, 7 and 10 years were classified according to the processing degree using NOVA. UPF consumption patterns based on total quantity were identified using a probabilistic Gaussian mixture model using participants with complete data and predicting for the total sample (n=8647). To assess whether the outcome trajectories from 4 to 13 years [body weight (kg), height (cm), body mass index (BMI) z-score, waist circumference (WC) (cm) and fat mass (FM) (%)] depend on UPF patterns, a mixed-effects model with linear and quadratic terms for age adjusted for confounders was used. Participants with at least 2 measurements at 4, 7, 10 or 13 years were included in this study (n range: 5885-6272). ResultsFour UPF consumption patterns were identified: constantly lower consumption (15.4%), constantly intermediate consumption (56.4%), transition from low to high consumption (11.2%), and constantly higher consumption (17.1%). Compared to the constantly lower UPF consumption, the constantly higher consumption pattern was associated with greater acceleration in body weight (β: 0.119; 95%CI: 0.027;0.212), BMI z-score (β: 0.014; 95%CI: 0.004;0.023), WC (β: 0.232; 95%CI: 0.144;0.319) and FM% (β: 0.200; 95%CI: 0.092;0.308) and with lower acceleration in height (β: -0.063; 95%CI: -0.111;-0.015). The constantly intermediate UPF consumption pattern was associated with greater acceleration in body weight (β: 0.123; 95%CI: 0.043;0.203), WC (β: 0.120; 95%CI: 0.045;0.195) and FM% (β: 0.146; 95%CI: 0.054;0.238). ConclusionConstantly higher and constantly intermediate UPF consumption throughout childhood were associated with worse growth and adiposity trajectories until adolescence.