SummaryBackgroundFew studies have tracked growth in children born extremely preterm (EP, <28 weeks’ gestation) beyond late adolescence. The relationships between growth parameters (including weight and BMI) through childhood and adolescence with later cardiometabolic health, are unclear in those born EP. We aimed to (i) compare growth from 2 to 25 years between EP and controls; and in the EP group (ii) determine the associations of growth parameters with cardiometabolic health.MethodsProspective state-wide cohort of all EP livebirths in Victoria, Australia, in 1991–1992 and contemporaneous term-born controls. Z-scores for weight (z-weight), height (z-height) and BMI (z-BMI) at 2, 5, 8, 18 and 25 years, and cardiometabolic health at 25 years (body composition, glucose tolerance, lipid profiles, blood pressure, exercise capacity) were measured. Growth trajectories were compared between groups using mixed models. The relationships between z-BMI changes/year, and being overweight at different ages, with cardiometabolic health were explored using linear regression.FindingsZ-weight and z-BMI were lower in EP than controls, but the gap decreased with age due to a more rapid rate of rise in z-weight and a decrease in z-height in the EP group compared with controls. Greater increases in z-BMI/year in the EP group were associated with poorer cardiometabolic health [coefficient (95% CI) per 0.1 z-BMI increase/year: visceral fat volume (cm3) 217.8 (160.9, 274.7), triglycerides (mmol/L) 0.45 (0.20, 0.71), systolic blood pressure (mmHg) 8.9 (5.8, 12.0), and exercise capacity (BEEP test maximum level −1.2 (−1.7, −0.7)), all p < 0.001]. The association between being overweight with poorer cardiometabolic health strengthened with age.InterpretationThe catch-up in weight and BMI by young adulthood in survivors born EP may not be desirable as it is associated with poorer cardiometabolic health. The associations of being overweight from mid-childhood with poorer cardiometabolic health may provide a window for intervention.Funding10.13039/501100000925National Health and Medical Research Councilof Australia.