WIC Infant and Toddler Feeding Practices Study: protocol design and implementation.

The federal Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), which began in the 1970s, has undergone revisions in the past several years, including revision to contents of the supplemental food "packages" in 2009 based on recommendations provided by an Institute of Medicine (IOM) committee of The National Academies. In 2010, the IOM held a workshop to examine and recommend research priorities for the program. The overall purpose of the current (ie, second) WIC Infant and Toddler Feeding Practices Study (ITFPS-2) is to conduct a nationally representative, longitudinal study of contemporary WIC infant and toddler feeding practices. This study will update earlier studies and collect information on variations in WIC program components. The study will also assess ways in which WIC may address obesity in early childhood and examine changes in feeding practices that may stem from the 2009 food package revisions. The sample is drawn from the universe of WIC sites nationally, excluding only those with an insufficient volume of eligible participants. Eligibility for the study includes the ability to be interviewed in English or Spanish. Approximately 8000 women and infants are being sampled, and ∼ 4000 are expected to participate. Eligible women are invited to participate during their WIC enrollment visit, and informed consent is sought. The design includes a core sample to be followed until the infant reaches age 2 y and a supplemental sample to be used in some cross-sectional analyses to ensure adequate representation of groups that might be underrepresented in the core sample. Participants will complete up to 11 interviews (core sample) or 4 interviews (supplemental sample) each except for the prenatal interview, which includes a quantitative 24-h recall of food intake for the infant. Eighty sites have been sampled across 26 states and 1 territory. Instruments have been developed and pretested in both English and Spanish, and interviewers have been rigorously trained. Recruitment and interviewing began in July 2013. This study will provide the only current large-sample longitudinal feeding data available on a nationally representative sample of infants in low-income families, and results will be available to inform the 2020 Dietary Guidelines for Americans for the 0- to 24-mo age group.