My vet would give Capstar (which is a pill that kills all adult fleas immediately) and then gives Frontline to put on them after the Capstar has done it's job. My vet says both Capstar and Frontline are safe for pregnant and nursing cats.
Do not give her OTC flea products. They are extreamly dangerous. Take her to the vet and the vet will give you flea medicine that is safe for her.
i agree the vets here will give frontline spray(not spot on) for pregnant/nursing cats/kittens this will kill the flees but you will have to treat your home, you can not buy frontline from the shop. they will also tell you the dose to give safely
REVOLUTION is safe for pregnant and nursing mothers! In fact, my vet said it would keep the fleas off the kittens too and prevent flea anemia. As the kittens rub against the mother, they get a little on them, or any fleas on the kittens crawl onto the mother and die there. It has worked for me.