In addition to the assumptions listed in Tables E-1 and E-2, several assumptions were used to distribute mother/infant pairs by the feeding method used. These are described as follows.
Assumptions on Infant Feeding in the WIC Program
A recent survey by the CDC on breastfeeding practices showed that among women participating in the WIC program, at 3 months postpartum 64 percent of mothers report breastfeeding in any amount with 36 percent reporting breastfeeding exclusively (CDC, 2004b). Based on these estimates, 28 percent (64 percent minus 36 percent) were partially breastfeeding at 3 months postpartum. The same survey indicated that at 6 months postpartum, 28 percent of mothers were breastfeeding in any amount with 11 percent exclusively breastfeeding (CDC, 2004b). Based on these estimates, 17 percent (28 percent minus 11 percent) were partially breastfeeding at 6 months postpartum. From these estimates (partial breastfeeding rates of 28 percent at 3 months and 17 percent at 6 months), a partially breastfed rate of 20 percent for infants ages 4 through 5 months of age was extrapolated.
For older infants, survey estimates of reported breastfeeding rates at 6 months (29 percent) and 12 months (14 percent) were used to extrapolate a rate of 21 percent breast-fed infants for the 6 through 11 month period (CDC, 2004b). The 21 percent of mothers who breast-fed infants were either fully or partially breastfeeding; the committee distributed them as 5 percent fully breastfeeding and 16 percent partially breastfeeding based on 2002 data from the Feeding Infants and Toddlers Study (Briefel et al., 2004a).
For the program cost analyses, breastfeeding rates were assumed to remain the same for both the current and revised food packages. Therefore, the following assumptions were used for the calculations: