Abstract 18234: Body Mass Index and Body Mass Index Z Score Trajectories from Birth to Adolescence

Abstract

Background: There are 3 critical periods for developing obesity during childhood: the fetal period; a period of adiposity rebound between 4-6 years; and during adolescence. The approach of latent class growth ascertains the most interpretable set of classes. The resulting categorical latent variable represents the groups of homogenous individuals within the class to which they belong.

Aim: We hypothesized that the early infantile period is another critical period at risk for developing obesity in adolescents using latent class growth models based on longitudinal height and weight data.

Methods: The study cohort included 913 healthy adolescent volunteers (396 males and 517 females) aged 15-18 years in Japan. Complete data sets for height and weight at birth, 1.5, 3, 6, 9 and 12 years of age, as well as at present, were obtained. Body mass index (BMI) and age- and sex-specific BMI Z scores were used as measures of obesity. Adiposity rebound was defined as the point of minimal BMI during infancy. Three-group latent class growth models were used in the present study.

Results: The BMI trajectories showed that individuals who consistently increased in BMI during infancy, i.e., they showed no adiposity rebound, were at the highest risk for adolescent obesity in both sexes. The Z score trajectories revealed that male subjects who were born with high Z scores and whose scores remained at high levels, as well as those who were born with low Z scores and whose scores had a sharp increase from birth to 1.5 years, were at risk for developing obesity. Female subjects who were born with relatively high Z scores and whose scores had a sharp increase from birth to 1.5 years were at risk. A representative figure is shown as Fig 1.

Conclusion: These data suggest that the early infantile period is important for preventing further development of obesity. Further more detailed studies are required to identify individuals and the exact timing of the critical periods during early infancy to prevent later obesity.