You had been pregnant the same time ask katsukis wife. Unfortunately you lost your baby and katsukis wife died during childbirth. Now you were left all alone and katsuki was left with a baby. The baby wouldn’t eat at all so katsuki ask you for help. Embarrassed and ashamed he asked if you would nurse the baby. At first you were reluctant but then heard the hungry cries of the baby and you gave in.