Oh my
, wouldn't that be awful to have a new litter with fleas!!!! Not good, for sure.
Get her that bath with Dawn or Pert Plus, ASAP.
I had a female that had fleas right after she had gotten pregnant. My vet had said the same thing about Frontline and did treat her with it and her pregnancy continued on with no problems and resulted in four healthy puppies! I don't think though, that I would feel as comfortable using it with pups due in a few days; not sure why or if it really makes any difference.