Baby joy! Chris Pratt and wife Katherine Schwarzenegger “couldn’t be happier” about expecting baby No. 1, an insider tells Life & Style exclusively. “And you can bet this will be the first of many,” the source happily adds.

“Well, at least three. Katherine has always said she wants a big family, at least four kids,” the insider explains of the couple’s family planning. “And they already have Jack, who they say is super excited and will be an amazing big brother.” The 40-year-old dad shares his 7-year-old son with ex-wife Anna Faris.

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It’s no surprise that the two lovebirds are over the moon right now. “Chris and Katherine are the perfect match and starting a family was always their number one goal,” the source gushes. “She’s already an amazing mom to Jack but she’s can’t wait to have a baby of her [own] to look after. She even says she’s looking forward to diaper duty.”

Needless to say, all of their loved ones are also thrilled as can be. “All the extended family members are calling them and congratulating them on the baby news,” the insider reveals. “Maria [Schriver] and Arnold [Schwarzenegger] were waiting for this moment to come, of course they’re overjoyed about becoming grandparents.”

As far as the upcoming arrival’s sex, things are still under wraps. “The gender is still a secret,” the source says. “I’m not sure if they’re planning to do a baby reveal or not.”

The news of the 30-year-old’s pregnancy broke on April 25 — and the same day, the happy couple was spotted on a bike ride together in Santa Monica. Chris rocked a mask while Katherine opted to go without as the dynamic duo rode around in athleisure looks. Plus, the brunette beauty’s baby bump was on fully display under her white T-shirt.

The sweet pair announced their engagement in January 2019 and tied the knot in Montecito, California that June. It seems as though the actor knew how great of a mother Katherine would be from the get-go.

“You’ve changed my whole world for the better. I’m so grateful to have found you,” he wrote to his lady love in honor of her birthday in December 2019. “You’re an incredible wife and stepmom.”