what is the first thing I need to do after finding out my cat is pregnant?

Plan a visit to your veterinarian. Just a good physical exam will do, and then perhaps even taking a stool sample to check for intestinal worms. That is a problem that we will sometimes see with cat pregnancy. The hormonal changes that cats go through during pregnancy can cause them to begin to shed intestinal worms, even though they might've been negative before then. Those are good approaches to take when you first find out about cat pregnancy.

The first thing you should do is to determine how far along the pregnancy is. If the birth is imminent, within a couple of days, start preparing. Ensure the cat has a dark, covered, comfortable place to give birth that's quiet, with access to water and food nearby so she doesn't have to move far. Cats prefer dark, quiet places to give birth, so try to control where she has her babies by gating off your bedrooms or closets.