Chris Pratt and Katherine Schwarzenegger are expanding their family ... because she's got another bun in the oven.
Arnold Schwarzenegger's daughter is pregnant with the married couple's third child ... TMZ has confirmed.
Unclear how far along Katherine is in this pregnancy ... ditto for whether it's a boy or a girl on the way.
For what it's worth, Chris and Katherine have been to some public events recently and there was no noticeable baby bump.