Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries: Pooled analysis of 2,182 population-based studies with 65 million participants

• Published in: The Lancet
• Main Authors: NCD Risk Factor Collaboration, Boddy, LM
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2020
• Subjects: RJ101 Child Health. Child health services; New Zealand; Pacific; Iceland
• Online Access: http://researchonline.ljmu.ac.uk/id/eprint/13810/; https://researchonline.ljmu.ac.uk/id/eprint/13810/10/Height%20and%20body-mass%20index%20trajectories%20of%20school-aged%20children%20and%20adolesecents%20from%201985%20to%202019%20in%20200%20countries%20and%20territories.pdf; https://doi.org/10.1016/S0140-6736(20)31859-6

Background: There are limited comparable global data on health and nutrition of school-aged children and adolescents. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected due to height gain, for school-aged children and adolescents. Methods: We used data from 2,182 population-based studies, with measurements of height and weight in 65 million participants. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in one-year age groups from five to 19 years in 200 countries. The model allowed for non-linear changes over time in mean height and BMI, and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Results: In 2019, there was a ≥20 cm difference in mean height of 19-year-olds between the tallest populations (Netherlands, Montenegro, Estonia and Bosnia and Herzegovina for boys; Netherlands, Montenegro, Denmark and Iceland for girls) and shortest populations (Timor-Leste, Lao PDR, Solomon Islands and Papua New Guinea for boys; Guatemala, Bangladesh, Nepal and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (Pacific island countries, Kuwait, Bahrain, Bahamas, Chile, the USA, New Zealand and, for girls, South Africa) and lowest mean BMI (boys and girls in India, Bangladesh, Timor Leste, Ethiopia and Chad, and girls in Japan and Romania) was ~9-10 kg/m2. In some countries, five-year-olds started with height or BMI that was healthier than the global median, and in some cases as healthy as the best performing countries, but became progressively less healthy relative to their comparators as 3 they grew older, by not growing as tall (e.g., boys in Austria and Barbados; girls in Belgium and Puerto Rico) or gaining too much weight for their height (e.g., girls and boys in Kuwait, Bahrain, Fiji, Jamaica and Mexico, and girls in South Africa and New Zealand). In other countries, growing children overtook their comparators’ height (e.g., Latvia, Czech Republic, Morocco and Iran) or curbed their weight gain (e.g., Sweden, France and Croatia) in late childhood and adolescence. When changes in both height and BMI are considered, girls and boys in South Korea, girls in some central Asian countries (e.g., Armenia, Azerbaijan, Turkey) and boys in central and western Europe (e.g., Portugal, Denmark, Poland, Montenegro) experienced the healthiest changes in anthropometric status over the past 3.5 decades because, compared to other countries, they achieved a much larger gain in height than they did in BMI. The unhealthiest changes – i.e., gaining too little height alongside too much weight for their height compared to other countries – were experienced in many countries in sub-Saharan Africa, Pacific island nations, New Zealand and the USA; boys in Malaysia; and girls in Mexico. Interpretation: School-aged children and adolescents’ height and BMI trajectories over age and time are highly variable across countries, which indicates heterogeneous nutritional quality and life-long health advantages and risks.