Trends in Height and BMI of 6-Year-Old Children during the Nutrition Transition in Chile

Abstract

Trends inheight and BMI of 6-year-old children during the nutritiontransition in Chile. Obes Res. 2005;13:2178 –2186.Objective: We analyzed trends in height and BMI and theirinteraction in 6-year-old Chilean children over the last 15years.Research Methods and Procedures: We calculated heightfor age z-score (HAZ), BMI z-score, prevalence of obesity,underweight, and stunting from cross-sectional nationalschool-based annual population surveys in 1987, 1990,1993, 1996, 2000, and 2002. Using mixed model analysis,we determined the risk of obesity according to height overtime as odds ratios (ORs) and 95% confidence interval andthe potential influence of height and year of study on BMIz-score.Results: Over the study period, height increased by 2.8 cmin boys and 2.6 cm in girls, whereas stunting declined from5% to 2% in both. Tallness increased by ~2%, BMI z-scoreincreased from 0.3 to 0.65 in boys and to 0.62 in girls,and HAZ increased from 0.47 in boys and 0.45 in girlsto 0 in 2002. Underweight declined from 4% to 3%,whereas obesity rose from 5% to ~14%. The probability ofobesity among tall children was significantly greater thanthat for normal height children (OR, 2.3 to 3.5). The lowestobesity risk was observed between 2 and 1 HAZ. TheOR for obesity in the stunted relative to normal heightchildren was variable, ranging from 1.23 to 0.65, whereas itwas significant and consistently positive (1.1 to 1.7) for boys and girls when it was compared with the lowestobesity risk according to height.Discussion: Tallness is significantly associated with increasedobesity risk in children, while stunting is also associated,but to a lesser degree.