Changes in High Weight-for-Length among Infants Enrolled in Special Supplemental Nutrition Program for Women, Infants, and Children during 2010-2018.

Background: Infants and young children with high weight-for-length are at increased risk for obesity in later life. This study describes prevalence of high weight-for-length and examines changes during 2010-2018 among 11,366,755 infants and young children 3-23 months of age in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). Methods: Children's weights and lengths were measured. High weight-for-length was defined as ≥2 standard deviations above sex and age-specific median on World Health Organization growth charts. Adjusted prevalence differences (APDs) between years were calculated as 100 times marginal effects from logistic regression models. APD was statistically significant if 95% confidence interval did not include 0. Results: Adjusted prevalence of high weight-for-length decreased from 2010 to 2014, and leveled off through 2018 overall, in boys and girls, those 6-11 and 18-23 months of age, and non-Hispanic whites, non-Hispanic blacks, Hispanics, and Asians/Pacific Islanders. For 12-17 months old and American Indian/Alaska Native infants and young children, adjusted prevalence decreased from 2010 to 2014, and then increased slightly through 2018. Among 56 WIC state or territorial agencies, 33 had significant decreases between 2010 and 2018, whereas 8 had significant increases. Between 2014 and 2018, prevalence decreased significantly in 12 agencies and increased significantly in 23. Conclusions: The results indicate overall declines in prevalence of high weight-for-length from 2010 to 2018, with a prevalence stabilization since 2014. Continued surveillance is needed. Obesity prevention strategies in WIC and multiple settings are important for ensuring healthy child growth.