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The Participants: Women and Their Children During the First Year of Life and at Six Years of Age

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 depended 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. Between March and June of 2012, FDA and CDC conducted the Year Six Follow-Up Study (Y6FU) to characterize the health, development, and diet quality of children who participated in the IFPS II. To qualify for the IFPS II, a healthy woman must have given birth to a singleton, full-term, or near-term infant weighing at least 5 pounds at birth. About 2,000 qualified and continued their participation through their baby's first year for IFPS II. To qualify for Y6FU, the mother had to have answered at least the prenatal and neonatal IFPS II questionnaires and not have been disqualified afterwards due to some medical reasons that affected infant feeding. Of 2,958 mothers who qualified for Y6FU based on IFPS II, 1,542 women participated in the follow-up study yielding a response rate of 52.1%.

With the exception of a brief telephone interview near the time of the infant's birth, all IFPS II data were collected using mailed questionnaires. A subset of women in the sample were asked to complete a modified Diet History Questionnaire prenatally and at about 4 months postpartum, adapted from one developed by the National Cancer Institute, National Institutes of Health. For comparison purposes, the same dietary information was collected from a sample of women of child-bearing age in the same mail panel who were neither pregnant nor postpartum. For Y6FU, two methods were used to collect the data to maximize the response rate. Mothers were first sent a questionnaire through the mail; however, those who did not respond after two attempts of mailed questionnaires were contacted by telephone to obtain the same information by telephone interview.

The Questionnaires of IFPS II

The Prenatal Questionnaire was sent when the woman was in the third trimester of pregnancy. It focused on factors associated with infant feeding choices, the baby's family medical history, and the mother's employment and social support system.

The Neonatal Questionnaire was sent to the mother when her infant was approximately 3 weeks old. This questionnaire examined factors that commonly occur near the time of the birth and that may affect infant feeding choices. It also asked about early feeding practices (including herbal intake by the infant), sources of information, sources of support, and any feeding-related treatment for jaundice.

The Postnatal Questionnaires consist of various combinations of eight modules that were mailed to the mother approximately monthly from the time her infant was 2 months through 7 months of age, then three times (about every 7 weeks) until 12 months of age. Many of the modules included questions that were asked in some months but not others. View the timetable [PDF-43k] for the administration of each topic.

Module A: Infant Feeding and Health

Module A was sent with each Postnatal Questionnaire. This module contained one of the major measures of the study, the infant's food frequency checklist. It also asked about dietary supplement and herbal intake by infants, details about breastfeeding and infant formula feeding, infant health and use of medicines, infant weight and length, stool characteristics, and feeding of commercial baby foods. In month 2 only, it included a measure of postpartum depression.

The food frequency checklist enabled researchers to analyze patterns of breastfeeding exclusivity, in particular whether mothers occasionally gave formula to an infant who was otherwise exclusively breastfed. Patterns of feeding foods other than breast milk and formula indicated the extent to which mothers followed current infant feeding guidelines, such as those published by national professional organizations. Information on whether foods fed to infants are baby foods or not provided information about exposure of infants to foods marketed for older children and adults, including foods fortified at levels only appropriate for older age groups.

Module B: Breastfeeding Cessation

Questions regarding breastfeeding cessation were included on each Postnatal Questionnaire, but they were answered only once, just after the mother had completely stopped breastfeeding. This module established the infant age when breastfeeding ceased and asked reasons for breastfeeding cessation and attitudes toward breastfeeding.

Module C: Food Allergy

Module C asked whether the mother believed that her infant had a food allergy or sensitivity, details of the implicated food, and details of the infant's symptoms, diagnosis, and treatment. Module C was sent at infant ages 4 months, 9 months, and 12 months.

Module D: Breastfeeding, Pumping and Expressing Milk

Module D asked for details about breastfeeding, the mother's sources of information about breastfeeding and breast pumps, any maternal dietary change due to breastfeeding, her reasons for supplementing with formula, and details of her experience expressing breast milk manually or with a breast pump. Module D also included a measure of the mother's embarrassment about breastfeeding and how she managed breastfeeding and work. This module was sent three times, at months 2, 5, and 7.  

Module E: Infant Formula

Module E asked for details about formula feeding, formula label use and understanding, sources of information, brand formula choice, brand formula changing, and food safety practices. Module E was sent four times, at months 2, 5, 7, and 9.

Module F: Information Sources

Module F had questions that were not asked together, but rather were inserted among questions in the other modules as appropriate. A question about sources of information on herbal products was sent at months 3 and 10. Questions about information sources for breastfeeding were sent in month 2, and questions about information sources for general infant feeding were sent in months 4 and 10.

Module G: Breastfeeding Awareness Campaign Evaluation

Module G included the direct measures of the mother's awareness of the National Breastfeeding Awareness Campaign messages and whether she agreed with those messages. Like those questions presented in Module F, questions from Module G were not asked as a separate module but rather as questions incorporated at appropriate places in other modules. Questions from Module G were sent in months 3 and 7.

Module H: Sleeping Arrangements, Child Care, Employment, and Health

Module H asked about all topics other than feeding. These included sleeping arrangements and position; child care and child care support for breastfeeding; details of the mother's employment and employer support for breastfeeding; how mothers managed to combine breastfeeding and work for pay; and the mother's overall health, weight status, and tobacco use. Module H was sent in months 3, 6, 9, and 12. A question about exposure to sunlight was administered at infant age 9 months.

Module J: Other Information

Questions about WIC participation and any severe health problems the infants may have encountered were placed at the end of each Postnatal Questionnaire. The presence of severe health conditions disqualified infants from participating in the rest of the study. Certain questions from other modules that did not fit elsewhere were also included in Module J in the months those modules were administered.

The questionnaires of Y6FU have the following five sections:

Section A inquires about child care and characteristics including who cares for the child when not in school and where the childcare occurs, type of school and grade, provision of an individualized education program or any special developmental services, cognitive stimulation at home, and the Strengths and Limitations Questionnaire for evaluating psychosocial development of children.

Section B documents information related to the child’s current health status and includes questions that document the measurement of the child’s weight and height. The mother was sent a tape measure and instructions on measuring the child’s height and was asked to report the measurement. She was also asked to weigh the child on a scale and report the weight. In addition, the mother was asked to report the last height and weight from a doctor’s office and the date of the measurements. Section B continues with questions about the mothers’ perceptions of her child’s weight, dental care, the child’s health, and the child’s use of herbal or botanical remedies. This section also has detailed questions about breathing difficulties and food allergy. Use of herbal or botanical remedies was included in this section on health rather than in the dietary intake section to measure use of such supplements as medicines rather than as beverages (e.g., herbal tea consumed as a beverage).

Section C asks about the child’s level of physical activity, screen time, and sleeping characteristics.

Section D begins with questions about exposure to pets and inhaled contaminants other than cigarette smoke, including air fresheners, scented candles, and pesticides. The remainder of the section is about the child’s eating patterns, dietary intake measured by a food frequency questionnaire, the food environment, such as the availability of healthful snacks, and parent control of the child’s diet and eating.

Section E is about the mother and family. It includes a family medical history, mother’s anthropometry, cigarette smoking by the mother and in the home, mother’s physical activity level, a depression scale for the mother, pregnancy and child feeding history, employment, insurance coverage for the child, and receipt of government benefits (including WIC participation for the 6-year-old and any children born after the 6-year-old).

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