Ethnic differences in height growth trajectories in contemporary children and adolescents: findings from the UK Millennium Cohort Study

摘要

Background: Height is an important biomarker for early life exposures that influence adult disease risk. Recent evidence suggests that height of UK children differs by ethnicity. Research to date on this subject was mostly based on cross-sectional data. The few available studies using longitudinal data focused on growth in the first few years in life, or for a short period during early childhood. We investigated whether height trajectories from early childhood into adolescence differed between ethnic groups, and the role of early life covariates. Methods: We used the data from 15 317 (White, South Asian, Black African and Black Caribbean) singletons in the UK Millennium Cohort Study. Mixed effects fractional polynomial models were applied to height repeatedly measured between 3 and 14 years. Results: Compared with White counterparts, South Asians (9% of study sample) were taller at 3 years by 0.5cm, had similar childhood trajectories, but became shorter in adolescence, particularly in girls, by 0.7cm (95% CI: 0.1, 1.2) at 11 years, increasing to 3.2cm (2.7, 3.7) at 14 years in girls. Boys were shorter by 0.5cm (0.2, 1.2) at 14 years. Height of South Asians relative to White children increased after adjusting for parental height and further for birthweight, but changed little with additional adjustment for prenatal and socioeconomic factors. Black African/Caribbean boys and girls (3.3% of sample) were taller at 3 years by 2.2cm (1.7, 2.7) and 3.2cm (2.6, 3.8), respectively. Differences increased to 3.8cm (3.0, 4.7) and 5.5cm (4.5, 6.4) at 11 years, but reduced to 3.1cm (2.0, 4.2) and 2.5cm (1.7, 3.4) at 14 years. Adjustment for early life covariates did not alter these differences. Conclusions: South Asians had shorter parents and lower birthweight. When adjusting for these factors height differences (relative to White children) increased, indicating greater intergenerational height gains and early life growth in South Asians. South Asians were slightly taller in early life, but shorter by adolescence. Black African and Black Caribbean children were the tallest, with smaller differences in adolescence. Distinct child-to-adolescence height trajectories may partly be due to their different growth tempo.