All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
There is no harm in breastfeeding your baby after the abortion; we do not know of any religious impediment to it unless the doctors decide that it would harm you or your baby. If this is the case, then you should not breastfeed him but nurture him by any other means, such as with baby food or milk or the like. The Prophet, sallallahu ‘alayhi wa sallam, said, "Harm should neither be inflicted nor reciprocated." [Maalik and others]
Allah knows best.