Changes in family income status and the development of overweight and obesity from 2 to 15 years: a longitudinal study

Background: An emerging body of research suggests the trajectory of a family's income affects children's health and development more profoundly than the often-measured income at a single time point. The purpose of this study was to examine the associations between changes in family income status, early-life risk factors, and body mass index (BMI) z-score trajectory from age 2 to 15 years. Methods: This longitudinal study employed a birth cohort (n = 595) located in a rural region of New York State. Data were collected through an audit of medical records and mailed questionnaires. Family low-income and BMI z-score trajectories were identified using latent-class modeling techniques that group children based on similar trends across time. We examined five early-life risk factors in relation to income and BMI z-score trajectories: maternal overweight/obesity, maternal gestational weight gain, maternal smoking during pregnancy, breastfeeding duration, and early-life weight gain trajectory. We used multinomial logistic regression models to estimate the odds of being in a BMI z-score trajectory group based on income trajectory and early-life risk factors. Results: Children who remain low-income throughout childhood were more likely to maintain overweight (AOR = 2.55, 95% CI = 1.03, 5.42) and children who moved into low-income during childhood were more likely to be obese (AOR = 2.36, 95% CI = 1.12, 5.93) compared to children who were never low-income. Maternal overweight/obesity was significantly associated with a child become obese (AOR = 8.31, 95% CI = 3.80, 18.20), become overweight (AOR = 2.37, 95% CI = 1.34, 4.22), and stay overweight (AOR = 1.79, 95% CI = 1.02, 3.14). Excessive gestational weight gain was associated with increased likelihood of a child becoming overweight trajectory (AOR = 2.01, 95% CI = 1.01, 4.00). Conclusions: Our findings further supports the growing evidence that there are several preventable early-life risk factors that could be targeted for intervention. This study provides new evidence that remaining in low-income and moving into low-income increases risk for adolescent overweight and obesity.