Derek Jeter knocked this baby announcement out of the park.
No additional details have been made public at this time but Kaius does share a birthday with his mom, Hannah, who turned 33 on May 5.
Their son joins big sisters Bella Raine, 5, Story Grey, 4, and River Rose, 17 months. And his arrival may not come as a total surprise to many sports fans, as the private couple also kept Hannah's pregnant with River under wraps until she was born.
Earlier this year, Derek shared rare insight into his private life as a dad during an exclusive interview with E! News.
"The great thing with having kids is regardless of how your day went, most days they're happy to see when you come home," he said. "And that's a great feeling. Regardless of how good or bad your day was, your kids at this age are happy to see you. It doesn't get any better than that."
And while he admitted he hasn't pushed them into playing sports, "I think it's important for them to do it at some point," Derek added. "The fun part of having kids that are so young is you can introduce them to all different types of career opportunities, all different things and you want them to find what they're excited about."
"They were taking tennis lessons for a while," he continued. "I want my girls to be involved in sports, just because there's lessons that you learn from playing sports like work ethic, teamwork, setting goals and you have to deal with failure."
In fact, it seems Bella may have already found what makes her happy. "My oldest loves taking pictures," he noted. "I just want them to find the thing that they're passionate about and then help them achieve whatever goals they may have."