Child-to-adult body mass index and height trajectories: a comparison of 2 British birth cohorts.

Markers of growth and changes of body mass index (BMI) are associated with adult chronic disease risk. To better understand such associations, the authors examined the 1946 (n approximately 5,300) and 1958 (n approximately 17,000) British birth cohorts to establish how child-to-adult height and BMI have changed across generations. Individuals born in 1958 were no heavier at birth than those born in 1946, but they were taller in childhood by about 1 cm on average, grew faster thereafter, and were 3-4 cm taller by adolescence. The 1958 cohort achieved adult height earlier and were taller by 1 cm, an increase that was entirely due to their longer leg length. BMI trajectories diverged from early adulthood, with a faster rate of BMI gain in the 1958 cohort than in the 1946 cohort, although the mean BMI at 7 years and rate of childhood gain had not shown an increase. By midadulthood, the 1958 cohort had on average a greater BMI (1-2 kg/m(2)), larger waist (6-7 cm) and hip (5 cm) circumferences, and a higher prevalence of obesity (25.1% vs. 10.8% in males and 23.7% vs. 14.8% in females). Changes in height and adiposity over a relatively short period of 12 years suggest the likelihood of opposing trends of influences on later disease risk in these populations.