Developmental Trajectories of Body Mass Index ：Patterns and Onset of Overweight among 1st to 6th Graders
Date Issued
2011
Date
2011
Author(s)
Lin, Li-Ju
Abstract
Objective: To investigate developmental trajectory patterns
of body mass index (BMI) and onset of overweight from the 1st to 6th grade. Methods: Data was obtained from the Children and Adolescent Behaviors in Long-term Evolution project. Participants included 1,609 students who were followed from the 1st to 6th grade (2001-2006). Data included height and weight of students and their parents. The concept of an ecological model was used to indentify the individual, family, school, and community level factors associated with BMI developmental trajectories among students. Group-based trajectory models and multinomial logit models were used in the statistical analysis. To explore the onset of overweight and related factors during elementary school years, we excluded students who were overweight at the beginning of 1st grade, leaving a total of 1249 participants for the survival analysis. Results: 1.There were significant sex differences in BMI developmental trajectory patterns from the 1st to 6th grade. 2. Among boys the four BMI developmental trajectory patterns included the normal that became slightly underweight group (40.62%), the persistently normal group (34.69%), the overweight that became obese group (18.15%), and the persistently obese group (6.54%). Among girls, the BMI developmental trajectory patterns included the persistently slightly underweight group (31.04%), the persistently normal group (40.18%), the persistently overweight group (22.03%), and the persistently obese group (6.76%). The mean BMI in each group demonstrated an upward trend over time. 3. In boys, developmental trajectories of overweight were significantly associated with after-school exercise, academic performance, family interactions, having overweight parents and father''s education level. In girls, developmental trajectories were significantly associated with watching television and using the computer, family interactions, peer interactions, and having overweight parents. 4. The onset of overweight during elementary school among boys ( 5.24 years) was earlier than that in girls (5.44 years). In addition, the onset of overweight occurred earlier in those living in Hsinchu County (5.27 years) compared to Taipei city (5.39 years). 5. In boys, early onset of overweight during elementary school was associated with having overweight parents, higher peer interactions, and less community interactions. In girls, early onset of overweight was associated with having overweight parents, earlier puberty, higher peer interactions, living in Hsinchu County, and coming from a low-income household. Conclusion: Among elementary school students, different patterns of BMI developmental trajectories exist in boys and girls. Similarly, the onset of overweight in elementary school differs by gender. Children who are overweight and obese in the 1st grade, or even in preschool, are an important target for health promotion policies and interventions. Based on our findings we recommend that children be encouraged to participate more in after-school exercise, reduce their time spent watching TV and using computers, pay attention to the content of their interactions with family and peers, and increase their community-level interactions.
Subjects
body mass index
development trajectory
overweight
obesity
onset of overweight
survival analysis
SDGs
Type
thesis
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