What can providers learn from childhood body mass index trajectories: a study of a large, safety-net clinical population

Acad Pediatr. Nov-Dec 2014;14(6):639-45. doi: 10.1016/j.acap.2014.06.009. Epub 2014 Aug 13.


Objective: To describe childhood weight gain using body mass index (BMI) z-score trajectories in a low-income urban safety-net population and identify among gender- and race/ethnicity-specific groups any trends for increased risk.

Methods: A retrospective cohort study was conducted among 2- to 12-year-old patients (2006-2013) visiting a safety-net provider. BMI z-score trajectories were calculated overall, for gender- and race/ethnicity-specific groups, and for peak BMI percentile subgroups to describe weight gain longitudinally.

Results: From 2006 to 2013, a total of 26,234 eligible children were followed for an average of 3.7 years. At baseline (mean age, 4.2 years), 74% of patients were at a normal weight compared to 65% at most recent observation (mean age, 7.8 years). All gender and race/ethnicity subgroups showed increasing average BMI z-scores during childhood. Children consistently under the 50th percentile and those of white race had the most stable BMI z-score trajectories. BMI z-score increased with increasing age in all subgroups. Hispanic boys and black girls had the most significant increase in BMI z-score during this observation period. Children observed in early childhood and whose BMI exceeded the 95th percentile at any time were often already overweight (20%) or obese (36%) by 3 years of age.

Conclusions: The entire population demonstrated an upward trend in BMI z-score trajectory. This trend was most notable among black girls and Hispanic boys. Many obese children were already overweight by age 3, and persistence of obesity after 3 years of age was high, suggesting that intervention before age 3 may be essential to curbing unhealthy weight trajectories.

Keywords: BMI; obesity; prevention; trajectory.

MeSH terms

  • Body Mass Index*
  • Child
  • Child, Preschool
  • Colorado / epidemiology
  • Disease Progression
  • Female
  • Humans
  • Infant
  • Male
  • Pediatric Obesity / epidemiology*
  • Pediatric Obesity / ethnology
  • Pediatric Obesity / prevention & control
  • Population Surveillance
  • Prevalence
  • Retrospective Studies