Should i treat my preggie cat fleas?

You need to flea treat them both, but you need to use a product safe for nursing cats. The best products are those from your vet, but if you won't take them there, then get Advantage or Frontline from the pet store. Do NOT get any other brand, as only these are safe for your cats and kittens. Products like Hartz will kill the kittens. Fleas will quite literally suck the life out of kittens by causing flea bite anemia, so it's nothing to be taken lightly. Change the bedding daily, and wash it in the hottest water you have to kill the flea eggs. Also vacuum around the nest daily to suck up the fleas that are outside the nest. That - and the Advantage or Frontline - should get the fleas under control in a few days.