The reason why the mother cat keeps licking her babies:
1. Cats are very clean animals. When a mother cat licks her kittens, she is probably cleaning them to prevent them from getting infected by bacteria.
2. When a mother cat licks her kittens' mouths forcefully, she is helping them learn to breathe and gasp for air. 
3. When a mother cat licks her kittens, it is also a way of expressing her love and care for them.
4. Cats have barbs on their tongues, and when a mother cat licks her kittens, she may be grooming them.
5. Newborn kittens are easily chilled, and the mother cat will keep them warm by licking them.
