Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. 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 from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5–19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9–10 kg/m 2 . 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). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, the...

Vitamin D deficiency in pregnancy may increase the risk of prenatal and early postnatal overweight in offspring. Clinical trials are warranted to determine the role of vitamin D in the early origins of obesity.

31Exposure to environmental pollutants, particularly during pregnancy, can have adverse consequences 32 on child development but little is known about the effects of pollutant mixtures on endogenous 33 metabolism in pregnant women. We aimed to identify urinary metabolic signatures associated with 34 low level exposure to multiple environmental pollutants in pregnant women from the INMA (INfancia y 35 Medio Ambiente) birth cohort (Spain, N=750). 36 35 chemical exposures were quantified in first trimester blood samples (organochlorine pesticides, 37PCBs, PFAS), in cord blood (mercury), and twice in urine at 12 and 32 weeks of pregnancy (metals, 38 phthalates, bisphenol A). 1 H nuclear magnetic resonance (NMR) metabolic profiles were acquired in 39 the same two urine samples. We explored associations between exposures and metabolism through 40 an exposome-metabolome wide association scan and multivariate O2PLS modelling. 41Novel and reproducible associations were found across two periods of pregnancy for 3 non-persistent 42 pollutants and across two sub-cohorts for 4 of the persistent pollutants. We found novel metabolic 43 signatures associated with arsenic exposure: TMAO and dimethylamine possibly related to gut 44 microbial methylamine metabolism and homarine related to fish intake, of tobacco smoke exposure 45 related to coffee metabolism and PCBs with 3-hydroxyvaleric acid, usually released under 46 ketoacidosis. 47 These findings will have implications for further understanding of maternal-fetal health, and health 48 across the life-course. 49