- Health Data: The study will also collect data from hospital birth records on the infants' weight at birth; and from WIC administrative records on the infants' length and weight and WIC package prescription at four times during the study (at ages 6, 12, 24 and 36 months). When participants consent to enroll in the study, we will ask them to sign a Health Insurance Portability and Accountability Act (HIPAA) form releasing the records for the study. If a child in the core sample has dropped out of WIC, we will request data from their health care provider or ask the participant to travel to the nearest WIC site to be measured.