Caregiver Feeding Practices and Late-Preschool BMI-for-Age z-Score Trajectories Among WIC-Enrolled Children: A National Longitudinal Study

Background/Objectives: Early childhood is an important period when growth and adiposity patterns emerge and may persist into later childhood. Children enrolled in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) face elevated obesity risk. We characterized BMI-for-age z-score (BMIz) trajectories from 24 to 60 months and their child-, caregiver-, and household-level correlates. Methods: This was a secondary analysis of the WIC Infant and Toddler Feeding Practices Study-2 (ITFPS-2) public-use dataset. We analyzed 5,583 BMIz observations from 2,247 dyads; adjusted models used 4,314 observations from 1,738 children. Linear mixed-effects models tested individual, interpersonal, and household predictors. Restriction and pressure-to-eat were lagged, time-varying exposures. Results: Mean BMIz was elevated at all waves (0.46 to 0.56). Obesity prevalence rose from 15.4% to 18.5%. Unconditionally, BMIz was stable from 24 to 48 months and rose by 60 months. Adjusted models linked higher BMIz to higher birth weight, Hispanic or Latino ethnicity, birth complications, maternal overweight or obesity, paternal overweight, prenatal smoking, adolescent maternal age, and lower maternal education. Male sex was associated with lower BMIz. Prior-wave restriction was associated with higher, and pressure to eat with modestly lower, subsequent BMIz. Household indicators showed no independent association. Conclusions: Caregiver and perinatal characteristics and feeding practices were the most consistent modifiable correlates of late-preschool BMIz. These observational, complete-case findings warrant caution. The 48–60-month window may be a promising period to target for WIC-based obesity prevention.