Diminishing benefits of urban living for children and adolescents’ growth and development

Abstract

Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for 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 these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified.

Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

“… 31 , 32 In some countries, equitable economic and agricultural policies and food programmes have improved the quality of nutrition, especially for the poor, 33 – 36 resulting in gains in height, whereas elsewhere weight gain occurred without substantial height gain, leading to increasing obesity. 4 , 11 , 19 , 37 These height gains were similar to those in Europe and north America during industrialisation and economic development. 38 Researchers have also detected a so-far unexplained decline in adult basal energy expenditure, 39 which might have contributed to the rise in obesity.…”

“…We did not report on height, a marker of the quality of nutrition and the living environment, and predictive of health throughout the life course, 15 as reported previously. 4 , 11 BMI is an imperfect measure of the extent and distribution of body fat, but is widely available in population-based surveys, and is used in clinical practice; it is also correlated with the more complex and costly dual-energy x-ray absorptiometry. 16 Cutoffs for thinness and obesity for school-aged children and adolescents are based on BMI distributions in a reference population, and were not selected to represent optimal BMI in epidemiological studies, as was done for adults, or optimal nutritional status, as for children younger than 5 years.…”

“…We pooled population-based studies with measurements of height and weight in samples of the general population from a database collated by the NCD Risk Factor Collaboration (NCD-RisC). Details of the data sources are provided in previous publications 1 – 4 , 10 , 11 and in the appendix (pp 47–51) .…”

“…Data were analysed using a Bayesian hierarchical meta-regression model. The statistical methods are detailed in previous publications 4 , 11 , 12 and in the appendix (pp 52–64) . In summary, the model had a hierarchical structure in which estimates for each country and year were informed by its own data, if available, and by data from other years in the same country and from other countries, especially those in the same region with data for similar time periods.…”

“…Trends in underweight and obesity have varied substantially across countries and age groups. 1 – 4 Furthermore, underweight and obesity have changed independently of each other in some regions. 2 Despite these heterogeneities, global data on how the combined (double) burden of underweight and obesity has changed in terms of magnitude and composition are scarce, and the latest data on their individual prevalence are from 2016.…”