The Nancy Mohrbacher Breastfeeding Reporter asserts that even after a baby has been bottle-fed for a year or more, the child can still be breastfed. When a baby has been breastfed, then becomes exclusively bottle-fed, the mother can go back to breastfeeding; this is accomplished through the process of relactation.
During relactation, the body learns to produce milk again, and the baby becomes accustomed to nursing again. If a woman's milk supply was high before, it is easier to reintroduce the child to nursing. Breastfeeding Magazine asserts that if a baby is younger than 4 months, it is easier to acclimate the baby to breastfeeding.