Diminishing benefits of urban living for children and adolescents' growth and development.

Optimal growth and development in childhood and adolescence is crucial for lifelonghealth and well-being1-6. Here we used data from 2,325 population-based studies, withmeasurements of height and weight from 71 million participants, to report the heightand body-mass index (BMI) of children and adolescents aged 5-19 years on the basisof rural and urban place of residence in 200 countries and territories from 1990 to2020. In 1990, children and adolescents residing in cities were taller than their ruralcounterparts in all but a few high-income countries. By 2020, the urban heightadvantage became smaller in most countries, and in many high-income westerncountries it reversed into a small urban-based disadvantage. The exception wasfor boys in most countries in sub-Saharan Africa and in some countries in Oceania,south Asia and the region of central Asia, Middle East and north Africa. In thesecountries, successive cohorts of boys from rural places either did not gain heightor possibly became shorter, and hence fell further behind their urban peers. Thedifference between the age-standardized mean BMI of children in urban and ruralareas was <1.1 kg m-2 in the vast majority of countries. Within this small range, BMIincreased slightly more in cities than in rural areas, except in south Asia, sub-SaharanAfrica and some countries in central and eastern Europe. Our results show that inmuch of the world, the growth and developmental advantages of living in cities havediminished in the twenty-first century, whereas in much of sub-Saharan Africa theyhave amplified.