Rising prevalence of stunting and obesity in Iranian schoolchildren: a three-year cohort study

This study aimed to determine the three-year changes in stunting and obesity among Iranian children aged 6–12 years. Data were collected from the first and second phases of the Shahroud schoolchildren eye cohort study, which were conducted in 2015 and 2018, respectively, in Shahroud, northeastern Iran. Students aged 6–12 years were invited to participate through cluster sampling in urban areas and by census method in rural areas. To determine stunting and obesity height-for-age z-scores (HAZ) and body mass index-for-age z-scores (BAZ) were calculated. Factors associated with changes in obesity and stunting were examined using linear and binomial regression models. Data from 5,246 individuals were available and analysed. The three-year changes in HAZ and BAZ were − 0.069 (95% CI: -0.092 to -0.045) and 0.241 (95% CI: 0.211 to 0.271), respectively. After three years, the prevalence of obesity and stunting increased from 9.6% to 12.49% and from 1.6% to 2.4%, respectively. After adjusting for covariates, the three-year increase in BAZ and HAZ was significantly greater in boys than in girls (β = 0.082, 95% CI: 0.032–0.131 and β = 0.055, 95% CI: 0.017–0.092, respectively). HAZ changes were also more negative in overweight and obese students. Age, sex, socioeconomic status, place of residence, and parental education were not associated with the incidence of stunting after three years. The risk of obesity was significantly lower in 10–12 year-olds than in 6-year-olds (P < 0.001). This study showed an increasing trend in stunting and obesity among school-aged children over three years. The increase in the prevalence of obesity is alarming, highlighting the need for new interventions considering the factors associated with obesity identified in this study.