The long-term cardiovascular implications of body size across the life course remain incompletely defined, particularly regarding transitions from childhood to adulthood. A prospective cohort analysis using UK Biobank data published in the International Journal of Obesity evaluated the independent and combined associations of childhood body size, adulthood body mass index (BMI), and life-course trajectories with incident cardiovascular disease (CVD) and mortality.

The study included 456,461 participants free of CVD at baseline. Childhood body size at age 10 was self-reported as thinner, average, or plumper relative to peers, while adulthood BMI was measured and categorized as normal weight (<25 kg/m²), overweight (25–29.9 kg/m²), or obesity (≥30 kg/m²). Cox proportional hazards models estimated associations with stroke, coronary artery disease (CAD), heart failure (HF), and mortality, with sex-stratified analyses.

During follow-up, 2,703 stroke, 13,349 HF, and 37,365 CAD events were recorded. Compared with average childhood body size, plumper childhood was associated with higher risks of HF (HR 1.21; 95% CI 1.14–1.28) and CAD (HR 1.08; 95% CI 1.04–1.11). Adulthood obesity showed stronger associations with HF (HR 1.91; 95% CI 1.80–2.02), CAD (HR 1.59; 95% CI 1.53–1.64), and all-cause mortality (HR 1.16; 95% CI 1.12–1.20). 

The highest risks were observed in individuals transitioning from thinner childhood to obesity in adulthood (HF: HR 2.18; CAD: HR 1.72; mortality: HR 1.21). Associations with stroke were modest and primarily observed in this trajectory.

Body size trajectories across life showed graded associations with cardiovascular outcomes. Progression to obesity from childhood was linked to the highest risks, with stronger associations observed in women.