It definitely can be dangerous for both the puppies and the mother since this might possibly be her first time in heat. But what happens happens, and you might want to call a specialist on this. It can go either ways, so professional help might be the best possible answer. This happens all the time. I don't think abortion should be your first option, though.
Call your vet - definitely!! Although your female came into season, her body is a bit immature to handle the demands a pregnancy will put on her. IF you decide to let her go to term with this litter, make sure you have good prenatal and post delivery care by your vet.