How Early Do Racial/Ethnic Disparities in Childhood Obesity Start?: Differences in Growth Trajectories and Early-Life Predictors By Race/Ethnicity

Background: Childhood obesity has become a primary social and public health concern that affects children from low-income and minority groups more than White and middle-class children. In fact, the prevalence of childhood obesity among Latino/a and Black children has been found to be higher (38.9% and 35.2%, respectively) than that of their White (28.5%) and Asian (19.5%) counterparts. Although these rates provide an insight into racial/ethnic disparities in childhood obesity, more research is necessary to understand how these disparities develop over time. In order to address this gap, the purpose of this study was to understand differences in growth trajectories from birth to age 9 among children from White, Black, and Latino backgrounds.   

Methods: Sample: This study used secondary data from Waves 1 (birth) through 5 (age 9) from the Fragile Families Child Wellbeing Study (FFCWS). FFCWS is a national prospective study of non-marital births in the United States. The final analytic sample size included 797 (23.71%) White participants, 1626 (48.38%) Black children and 938 (27.90%) Latino participants.  

Measures: The main measurement used was Body Mass Index (BMI) z-scores. BMI z-scores were used to determine the growth trajectories. Maternal education, maternal age, income, maternal relationship with baby’s father, smoking during pregnancy, number of children in the house and maternal pre-pregnancy BMI were used as predictors.  

Data Analysis: Group-based trajectory modeling was used to identify different patterns of growth over time. Bayesian information criterion (BIC), posterior group membership probabilities, and Wald tests were used to identify the optimal number of groups for each racial/ethnic group. Multivariate logistic regression was used in order to examine whether any of the demographic or maternal health variables were predictors of developing a high-rising trajectory.  

Results: The results demonstrated that children from different racial/ethnic backgrounds had qualitatively different growth trajectories from birth through age 9. Specifically, among White children, a three-group trajectory solution was found. The three trajectories included a “stable”, a “mid-rising”, and a “high-rising” group trajectory. Among Black children, the best solution was a two-group solution, with a “slow-rising” and a “mid-rising” trajectory. For Latino children, the best model was also a two-group solution with a “slow-rising” and a “high-rising” trajectory. The results demonstrated that among White children, more number of children in the house and higher maternal pre-pregnancy BMI were predictors of developing a high-rising trajectory. Among Black and Latino children it was found that higher maternal pre-pregnancy BMI was a significant predictor of following an at-risk trajectory.

Implications: In a sample of mostly low-income, minority participants, this study found that White and Latino children had the most detrimental growth over time. More research and social work interventions need to tackle these populations. Given that maternal pre-pregnancy BMI was identified as the main predictor of at-risk growth, it is necessary to develop interventions that aim to prevent childhood obesity during conception by reducing high pre-pregnancy BMI. Future studies should focus on identifying modifiable factors that can prevent childhood obesity development.