Behavioral Changes

• According to "Cat Owner's Home Veterinary Handbook" one of the first signs of pregnancy is a change of normal behavior. She may lose all interest in playing, and may become quieter or more affectionate.
  
  

Appetite Change

• Before she starts showing any physical signs of pregnancy, the pregnant cat will have a noticeable increase in appetite. She may also wolf her food down and steal food from other pets or people.
  
  

First Physical Sign

• According to Cats of Australia, the first physical sign of pregnancy are that the cat's nipples will turn pink. This means she is at least 3 weeks pregnant.
  
  

Other Signs

• By the fifth week, the cat will get a larger belly and her breasts may leak milk. She may also experience morning sickness.
  
  

False Pregnancy

• "Cat Owner's Home Veterinary Handbook" also mentions that some female cats, after mating, will have a false pregnancy because their bodies are producing too much progesterone. All signs go away normally in 35 to 40 days.