The insert that came with my sealed box of Advantage says it is safe for use on pregnant and lactating mother cats and will protect the nursing babies she comes into contact with. It goes on in the instructions to say that once the kittens are weaned, to dose them with the dark orange tube. It is regular Bayer Advantage - the only difference being that I order mine online from PetShed and it come from Australia at half the price. Would the instructions for use be that different? If I had the kittens, I would go ahead and give them a dose of the medication to get rid of the fleas. When we brought Emily and Eliot to the vet, we had no idea of their age but they had already had flea treatment and still had a few fleas so our vet gave them each another orange dose of Advantage to prevent tape worms and anemia. The orange tube only has 6-7 drops in it. (.4ml)