And hopefully her last unless you are an experienced, responsible and knowledgable breeder. You should have her spayed as soon as possible either right now and then she won't have the babies or else after they are born and weaned. There are far to many cats in this world being put to sleep and abandoned for people to let their cats have litters for no particular reason.
Do you know who the father is? What if he is diseased and now your female cat has the disease too and will pass it on to her babies as well?