My cat appeared with a newborn kitten but I saw no evidence of afterbirth. The kitten was dry and is healthy. It has been almost seventy two hours and no other babies have been born. I believe she still has babies in her that are yet to be born but how would I know. Could she have delivered them somewhere and only brought one home? Is it abnormal that no signs of aftterbirth were in her nesting area?

Cats eat the afterbirth. If she seems to still have babies in her though and isn't delivering, call the doctor because they could die and she could get a bad infection.