False pregnancy, which is also called pseudopregnancy, is uncommon in cats. Pseudopregnancy can occur when a cat has been induced to ovulate but doesn’t actually get pregnant.
A cat with pseudopregnancy might actually look pregnant in some ways, such as with mammary gland development and even milk production. Behavior might also change. A cat might develop nesting behavior to prepare for kittens.
A vet can determine a false pregnancy by looking for fetal kittens with x-ray or ultrasound, depending on the time since ovulation. Once signs develop, they usually stop on their own in cats after one to three weeks and do not require specific treatment.