Breast milk is typically discussed in three stages: colostrum, transitional breast milk, and mature breast milk. This is also called Lactogenesis I, II, and III. Colostrum is what your body makes from mid pregnancy to birth. Your breastmilk transitions once your placenta is birthed until 20-30 hours after birth and this is transitional breast milk. Once your milk is fully transitioned usually by one week postpartum this is mature breast milk. During these stages your baby is given exactly what your baby needs.