Do you have a lot of flies around the litter box? Maggots would only be present if the flies are laying eggs on your cat's fresh stool.
Maggots can infest the skin of cats/dogs also. If there is a wound in the skin, or feces on the fur, the flies will lay eggs there, and the maggots can then start eating through the skin. It is very gross, and can kill an animal if not treated right away. If there is any afterbirth mess still on her fur, this can attract flies.
One thing that some people confuse with maggots are tapeworms. Tapeworms are small, white worms that you can see on fresh feces, and sometimes crawling around the fur around the anus. The tapeworms are smooth, while maggots have a more rough appearance. Tapeworms move slow, while maggots tend to move very fast. Tapeworms can be caught from the cat eating fleas, or also if they eat rodents or rabbits, which carry the tapeworms. The tapeworms will dry up, and then they look like small sesame seeds, and you can find these on the cats fur or on their bedding.
This website has a picture of the tapeworms in stool and the dried segments on the fur. They have a dog in the pictures, but they look the same in cats. http://www.thepetcenter.com/exa/worms.html Scroll down to the last section.
Do you think that it might be tapeworms you are seeing vs. maggots? Please reply to discuss further!