A trajectory analysis of body mass index for Finnish children

Abstract

The aim of this study is to investigate the early development of body mass index (BMI), a standard tool for assessing the body shape and average level of adiposity for children and adults. The main aim of the study is to identify the primary trajectories of BMI development and to investigate the changes of certain growth characteristics over time. Based on our longitudinal data of 4223 Finnish children, we took anthropometric measurements from birth up to 15 years of age for birth years 1974, 1981, 1991 and 1995, but only up to 11 years of age for the birth year 2001. As a statistical method, we utilized trajectory analysis with the methods of nonparametric regression. We identified four main trajectories of BMI growth. Two of these trajectories do not seem to follow the normal growth pattern. The highest growth track appears to yield to a track that may yield to overweight and the low birth BMI track shows that the girls' track differs that of boys on the same track, and on the normal tracks. The so-called adiposity rebound time decreased over time and started earlier for those on the overweight track. According to our study, this kind of acceleration of growth might be more of a general phenomenon that also relates to the other phases of BMI development. The major change seems to occur especially for those children on high growth tracks.

Group‐based trajectory modelling for BMI trajectories in childhood: A systematic review

“…Table provides an overview of the characteristics of the included studies and their quality ratings, seven of the 14 studies considered of good quality and seven of fair quality . A total of 11 of the included studies were conducted in high‐income countries: one in Singapore, one in Germany, two in Australia, three in the United States, one in Spain, two in Finland, and one in France . One study pooled data from five high‐income countries, and one pooled data from one middle‐income and 10 high‐income countries .…”

“…Sample sizes varied across the studies, ranging from 246 to 12 050, and the median was 1469. Almost all (n = 13) of the studies used data from cohort studies, and one used data from a randomised controlled trial (RCT) . The RCT investigated the effects on the primary prevention of asthma of an intervention comprising house dust mite avoidance and omega‐3 fatty acid supplementation from birth to 5 years.…”

“…Of the 10 prospective studies, five recruited women during pregnancy, three recruited newborn infants, and two used a combination . Of the retrospective cohorts, two used register‐based data, one of which also included a questionnaire follow‐up, and one recruited adult participants with completed weight and height data in childhood …”

“…Of the included studies, five studies identified trajectories in the first 2 years of life, with one of them only tracking BMI in the first year . The other nine studies identified trajectories comprising longer time spans, ranging from 0 to 3.5 years to 0 to 15 years …”

“…Table shows information on the statistical methods used in each study including the outcome measures and predictors explored. Five of the studies used BMI z ‐scores based on WHO child growth standards, one study used BMI z ‐scores based on 1990 standards for British children, one study used BMI percentiles based on WHO growth standards for their trajectories, and seven studies used actual BMI for their trajectories, five of which used percentile curves or reference charts as a comparison (Table ). It was unclear in two studies if the trajectories were compared with a reference chart .…”