The Participants: Women and Their Infants
Approximately 4,000 pregnant women from across the nation began their participation in the Infant Feeding Practices Study II (IFPS II) between May and December 2005. The success of the research depends upon a high level of participation by the selected women over the course of 15 months. To maximize participation rates, the study selected the sample from a national consumer opinion panel consisting of 500,000 households from throughout the United States. Women who regularly volunteer to participate in opinion surveys are more likely to comply with the lengthy requirements of the IFPS II than are women chosen randomly from the U.S. population.
While the study begins with 4,000 pregnant women, about 2,250 are expected to qualify and continue their participation through their baby's first year. To qualify, a healthy women must give birth to one healthy, full-term or near-term infant weighing at least 5 pounds at birth.
With the exception of a brief telephone interview near the time of the infant's birth, all data will be collected using mailed questionnaires. A subset of women in the sample will be asked to complete a modified Diet History Questionnaire prenatally and about 4 months postpartum, adapted from one developed by the National Cancer Institute, National Institutes of Health. For comparison purposes, the same dietary information will be collected from a sample of women of child-bearing age who are neither pregnant nor post-partum.