ObjectiveTo investigate whether size at birth and growth trajectories in infancy and childhood are associated with determinants of cardiovascular and metabolic risks in young adults born extremely preterm (EP, <26 weeks of gestation).MethodsWe used longitudinal data from the EPICure study of 129 EP survivors up to 19 years in the UK and Ireland in 1995. Determinants of cardiovascular and metabolic risks at 19 years included the presence of metabolic syndrome, body mass index (BMI) and systolic blood pressure (SBP). Predictors were birth weight for gestation and gain in weight z-scores in the following periods: birth–postmenstrual age of 40 weeks (term), infancy (term–2.5 years), early childhood (2.5–6.0 years) and late childhood (6–11 years).ResultsMetabolic syndrome was present in 8.7% of EP participants at 19 years. Compared with subjects without metabolic syndrome, those with metabolic syndrome tended to have a smaller size at birth (difference in means: −0.55 SD, 95% CI −1.10 to 0.01, p=0.053) and a greater increase in weight z-scores from term to 2.5 years (difference in means: 1.00 SD, 95% CI −0.17 to 2.17, p=0.094). BMI at 19 years was positively related to growth from 2.5 to 6.0 years ( β : 1.03, 95% CI 0.31 to 1.75, p=0.006); an inverse association with birthweight z-scores was found in the lower socioeconomic status group ( β : −1.79, 95% CI −3.41 to –0.17, p=0.031). Central SBP was positively related to growth from 2.5 to 6.0 years ( β : 1.75, 95% CI 0.48 to 3.02, p=0.007).ConclusionSize at EP birth and increased catch-up in weight from 2.5 to 6.0 years were associated with BMI and central SBP in early adulthood.