Let the countdown begin! Katherine Schwarzenegger is expecting baby No. 1 with husband Chris Pratt later this year, but when exactly is her due date? Turns out, fans won’t have to wait much longer for their bundle of joy.

During a recent virtual appearance on The Tonight Show, the author’s famous father, Arnold Schwarzenegger, accidentally spilled the beans.

“Yeah, can you believe that? I mean, that is really exciting news that Katherine now, you know be pregnant and have a baby. I don’t know when exactly,” he said on May 18, referring to when his 30-year-old daughter is expected to give birth. “Sometime this summer. And, inevitably, I’m really looking forward to playing around with whatever it is, she or he, and have some fun.” Oops!

In April, Life & Style confirmed the couple’s exciting news. “Well, that wasn’t very surprising,” a source divulged at the time, just over one month shy of their first wedding anniversary. “Chris and Katherine have been actively trying to have a baby and now the secret is out — she’s pregnant.”

Chris, 40, is already dad to son Jack Pratt, whom he shares with ex-wife Anna Faris. Luckily, Katherine has an amazing relationship with the 7-year-old.

Katherine Schwarzenegger, Chris Pratt and Jack Pratt Photos

“Chris is blown away at how [Katherine] can handle temper tantrums and silly fits without breaking a sweat,” a second insider revealed to Life & Style. “That’s one of the reasons why he fell in love with her. Jack adores her and Anna appreciates that Chris chose so well. They really are one big happy family.”

Lately, Katherine has been taking daily walks amid the coronavirus pandemic and flaunting her baby bump. Most recently, she stepped out in Los Angeles while walking her dogs on May 28, and it doesn’t sound like the soon-to-be mama will be slowing down anytime soon.

She’s “constantly on the go,” an insider told Life & Style, noting that her husband “is always there making sure she doesn’t over-do it.” They added that if Chris “thinks she’s pushing herself too hard, he’ll tell her. And he’ll happily run errands if she’s suffering from a bout of morning sickness or is feeling tired.”

We can’t wait to meet their little one!