If she doesn t bury her waste, there s a highly probable chance that the kittens won t either. This is an ongoing lesson. The kittens learn from watching her, as much as anything. If the kitten is removed at 5-8 weeks, they don t benefit from this continuing lesson. This, then, is my 3 rd reason for waiting.
Kittens get passive immunity to illness from the mother s milk.
This starts to decrease and then disappear at about 6 weeks of age. This is why we like to start their shots at that age. One shot doesn t give immunity. It lasts only until the next shot is given 4 weeks later. This is why kittens have a series of 3 shots, the last one falling at about 14-16 weeks of age.