The purpose of this secondary data analysis from two different samples was to examine the effect of early supplementation with manufactured milks on breastfeeding status at 20 weeks postpartum in mothers of healthy term infants. In two convenience samples of 120 and 223, respectively, breastfeeding mothers were followed up for 20 weeks postpartum or until weaning occurred. The breastfeeding rate at 20 weeks postpartum was significantly greater for mothers who reported feeding exclusively mother's milk the second week after delivery compared with mothers who breastfed and simultaneously supplemented with manufactured infant milks. Of the mothers in samples one and two who exclusively fed human milk during week 2 postpartum, 63.0% and 59.7%, respectively, were still breastfeeding at week 20, compared with 28.1% and 24.2%, respectively, who supplemented with artificial milks. There was no significant difference between these two groups of mothers and their intended duration of breastfeeding. Early introduction of supplemental bottles of artificial milks is associated with a decrease in the amount of human milk the infant receives as well as with early weaning.