There's a few reasons a mother might not be able to breastfeed her second child after breastfeeding the first child. It can have anything to do with her employment, if it was odd hours that she might be working, or work travel time that she might have to take that could interfere with pumping scheduling, any of that time away from the baby might be difficult. It could be medication, it could be any medical reasons. If the mother is on medication or if the baby was a preemie the baby might have issues latching on and learning to breastfeed, or the mother and baby learning together to breastfeed. In our case, it was adoption. Our fourth child was adopted and so we went with a formula feeding route.