Investigators evaluate 35-year height and BMI trajectories for 200 countries and 65 million participants.
A new global study revealed unhealthy growth trends in several countries, including the United States. Overall, the study demonstrated wide variations in height and BMI among school-aged children in 200 countries from 1985-2019.
Investigators from the Non-Communicable Disease Risk Factor Collaboration pooled data from 2181 population-based studies in order to assess height and BMI trends among individuals aged 5-19 years. Overall, the data included 65 million participants across the globe, thus covering 98.7% of the world’s population for 2019.
Using a Bayesian hierarchical model, they estimated mean height and mean BMI by country, year, sex, age.
Thus, in 2019, the countries with the tallest 19-year-old populations were the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys—and the Netherlands, Montenegro, Denmark, and Iceland for girls. The countries with the shortest populations were Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boy—and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls.
The estimated mean difference between these countries was ≥20 cm.
The countries with the highest BMI were the Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls — South Africa for girls. The countries with the lowest mean BMI were India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls—and Japan and Romania for girls
The estimated mean difference between these groups was about 9–10 kg/m2 (or roughly 25 kg).
They also reported that children aged 5 years tended to have a healthier BMI or weight in comparison to later years as they aged.
“In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand),” they wrote.
On the flipside, they noted that children in other countries either overtook their comparators in terms of height or improved weight gain as they grew older.
The unhealthiest changes, defined as gaining too little height or too much weight in comparison with other countries, were most notable in many countries in sub-Sabaharan Africa, New Zealand, and the USA for both boys and girls.
The authors commented on the implications of their findings and what that potentially reveals about childhood nutrition.
“The finding that children in some countries grow healthily to age 5 years but do not continue to do so during school years shows an imbalance between investment in improving nutrition and growth before age 5 years and doing so in school-aged children and adolescents,” they wrote.
They concluded by suggesting that these findings should motivate further investment in policies and interventions aimed at supporting health growth in individuals from birth to adolescence. These measures may include enhanced nutritional quality, a healthier living quality, and provision of high-quality preventative and curative care.
The study, “Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries and territories: a pooled analysis of 2181 population-based studies with 65 million participants,” was published online in The Lancet.