Should I breastfeed if there is blood in my baby's spit-up?
If a mother’s nipples are damaged, they may bleed when the baby is breastfeeding and the baby will take in some blood. This usually happens when the nipple is first damaged. Mothers may notice blood on the nipple or in expressed milk. It may also appear in the baby’s spit-up,vomit or stool (poop). It’s important to make sure the blood is coming only from the damaged nipples and not from another breast problem or from the baby.