Public health: Diminishing health benefits for young people in cities

Historical growth and developmental advantages for children and adolescents living in cities over rural areas may have diminished in most countries in the twenty-first century, suggests a Nature paper. However, urban advantages were amplified for boys living in some regions of Africa and Asia. The findings, based on an analysis of 71 million young people from 200 countries worldwide, may help to inform policies and programmes that aim to improve growth and development outcomes.

Optimal growth and development in childhood and adolescence is crucial for lifelong health and wellbeing; it is influenced by nutrition and the living environment at home, in the community and at school. However, there are limited data comparing growth and development outcomes in urban and rural communities for this age group. Consequently, many policies and programmes that aim to enhance healthy growth and development in school ages have a narrow focus that often assumes city living is disadvantageous.

NCD Risk Factor Collaboration, an international group of 1,500 researchers and physicians, collated height and weight data from 71 million young people, aged 5–19 years old, who lived in rural and urban areas in 200 countries between 1990 and 2020. They found that in 1990, children and adolescents in cities were taller than their rural counterparts in all but a few countries. However, by 2020, the urban height advantage became smaller in most countries, and in many wealthy western countries — such as the UK, USA and France — reversed into a small urban disadvantage. The exception was for boys in most countries in sub-Saharan Africa, and in some countries in the Pacific, south Asia and the Middle East. In these countries, successive cohorts of rural boys either did not gain height or possibly even became shorter. Body-mass index, which is a measure of whether a person is underweight or overweight for their height, increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa, and some countries in central and eastern Europe.

Understanding the trajectories of growth and development in children and adolescents could guide efforts to improve health outcomes in these important ages, which is something that is particularly relevant given the rise in poverty and cost of food, influenced in part by the COVID-19 pandemic and the war in Ukraine, the authors conclude.