From the 2006 National Immunization Survey
Was [child] ever breastfed or fed breast milk?
(If No, the child is not considered a breastfed newborn and is not included in the denominator.)
How old was [child's name] when (he/she) was first fed formula?
The National Immunization Survey (NIS) is conducted annually and collects data on children through age 35 months, and enables CDC to calculate breastfeeding rates each year. Because children are 19-35 months of age at the time of the NIS interview, each cross-sectional survey includes children born in three different calendar years. Using a computer-generated list, the NIS identifies households across the United States with children aged 19–35 months and interviews the person who is most knowledgeable about the child’s immunization status (“caregiver”). Starting January 2003, all respondents to the household telephone survey were asked questions related to breastfeeding, with modification of breastfeeding questions in 2004 and 2006. Survey years are combined to calculate breastfeeding by year of child’s birth (cohort) instead of year in which the participant was surveyed. To calculate breastfeeding indicators by year of child birth, data are combined across all available survey years1.