Katherine Schwarzenegger and Chris Pratt are ''so happy'' to be expecting their first child together.

The couple - who tied the knot in June 2019 - were reported over the weekend to be set to welcome a baby into the world, which will be a brother or sister for Chris' seven-year-old son, Jack, whom he has with ex-wife Anna Faris.

And now, an insider has said Katherine and Chris had originally been keeping the news private so they could ''enjoy this time'' for themselves, but are now ''excited to share the news with everyone''.

Speaking to People magazine, a source said: ''Chris and Katherine are so happy. They wanted to enjoy this time privately for as long as possible, but now that Katherine is showing more, they're excited to share the news with everyone.''

The news came after Chris admitted his wife will make ''a great mum one day''.

The 40-year-old actor said: ''She has changed my life for the better in so many ways. My heart, my soul, my son I feel are all so safe with her. She's a great step mum. She's, God willing, going to be a great mum one day. She's got great parents, great siblings, she fills in all my many deficits. My nickname on these press tours is Yard Sale because I'm such a scatterbrain. And she doesn't mind helping me with that stuff. It's a good match.''

Katherine's father Arnold Schwarzenegger has also spoke about the prospect of his daughter starting a family with Chris - whom she married in June 2019 - as he said he is ''looking forward'' to becoming a grandfather, but isn't ''pushing'' the pair to have kids.

He explained: ''I don't push it because I know it's going to happen eventually. It's up to Chris and her when they want to do that but I'm looking forward it to, yes.''