I personally wouldn't recommend it. They do sell Frontline at petstores like Petsmart and Pets Supplies Plus, probably Petco too for that matter, but make sure you read the directions carefully to see if it is indeed safe for momma cats. If you do get that, I would only put it on the momma, for the babies I would get a flea comb and fix a bowl of really hot dish soapy (like Dawn, that is the most suggested one for this) water, comb the babies and then put the fleas that come off them into the bowl of soapy water, it will drown them. You may have to do this a few times. I would also regularly wash the bedding that momma and babies are in