A cat’s behavior can frequently change when it learns that its owner is expecting a baby, so they might show threatening behavior toward their human owner.
Cats might not want their pregnant owner in their space because they are angry and in pain from chronic stress. So, they are likely to show territorial aggression.
There are several stages in pregnancy where you might feel emotional or quite clingy. So, you might pet your cat more, but your cat might dislike this, since cats seem to have a limit to how much petting they will tolerate!
A cat could attack a pregnant woman without hesitation if she has any past trauma related to them. A cat may harbor resentment for a very long time if a pregnant woman previously beat or yelled at her.