Mother cats can reject kittens for a number of reasons. Health and anatomical problems may cause her to reject kittens unlikely to survive, allowing her to concentrate her energy on nursing the rest of the litter.
Begin handling kittens only when the mother is comfortable with allowing human interaction. Forcing this step too early can result in rejected kittens. One to two weeks is the earliest a kitten should be handled.
Handle kittens only under the mother's supervision. Do not remove the kittens from her care or from her sight while handling.
Keep handling of newborn kittens limited to 10 to 15 minute intervals. Continually observe the mother cat's reaction to the handling; if she becomes agitated or restless, return the kitten to her.
Remove any rejected kittens from the mother's care immediately; the presence of a rejected kitten may cause the mother to reject further litter mates.