Methods for the Year 6 Follow-up Study of Children in the Infant Feeding Practices Study II

Objective: We describe methods used in the Year 6 Follow-Up (Y6FU) of children who participated in the Infant Feeding Practices Study II (IFPSII). This study consists of a questionnaire administered 6 years after the IFPSII to characterize the health, development, and diet quality of the children.

Methods: The Y6FU sample was a subset of those who participated in IFPSII. The IFPSII participants were drawn from a national consumer opinion panel; neither the IFPSII nor the Y6FU sample is nationally representative. The Y6FU sampling frame included all qualified participants who answered at least the first postnatal questionnaire. One questionnaire was administered by mail in 2012, and nonrespondents were contacted for a telephone interview. Survey topics included measures of health, development, diet, physical activity, screen time, and family medical history. We attempted to contact 2958 mothers and obtained completed questionnaires from 1542, a response rate of 52.1%. We conducted 2 sample evaluations, 1 comparing respondents and nonrespondents on data from IFPSII and the other comparing Y6FU respondents with 6-year-old participants in the National Survey of Children's Health.

Results: Y6FU mothers are more likely to be white, married, older, and of higher education and income than both nonresponders and nationally representative mothers. Comparisons also revealed health-related differences and similarities.

Conclusions: Although not nationally representative, the Y6FU provides a valuable database because of its wide coverage of diet and health issues and its unique ability to link early feeding patterns with outcomes at age 6 years.