Kittens can be born with worms transmitted from their mother. Most of the time we won’t see them in the stool. This is why deworming is so important at a young age. Most deworming programs start as early as 2 - 3 weeks of age. Deworming kills the adult stage of the worm. As eggs hatch, additional deworming is necessary. For this reason, your veterinarian will likely recommend multiple doses.