Why does a mother cat sometimes eat her kittens?

• Mother cats sometimes eat their kittens if they are unhealthy or have died. This is nature and I would assume the nutrients are needed to feed the other kittens. But sometimes a mother cat will just ignore the ailing or dead kitten. 
  
• The mother cat might eat her kittens if you mess with them too much when they are little. Cats detect a lot by smell, and if the kitten smells wrong (i.e, of you) it might assume it's unhealthy and kill it.
  
• Some cats are genetically abnormal, and can't produce the hormones which trigger maternal behaviour. That means they might treat their own kittens as prey. If you see a mother cat kill her entire healthy litter, you probably shouldn't breed from her again. Be wary of breeding from her surviving kittens as well - it's a genetic trait, which means the problem might be passed on. 

• Kittens born in winter, when they aren't likely to survive, are sometimes killed to save strength for the mother.

• If you put your cat under too much stress, she might decide she can't protect her kittens and give them up as a lost cause. You need to give her a quiet, dark place to make her nest, and leave her alone most of the time. If she moves her nest, stop bothering her.
  
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