"I have a new kid. Since last I played, I have a new kid," said the former O.C. actor, 40. "I have a boy, and he's a dream. He's a dream boy."
Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.
Meester revealed her baby bump in late March, when she was photographed out and about in Los Angeles with her hands on the small of her back, wearing a gray T-shirt underneath a pair of long overalls.
"Somebody just told me I got fat. That's really nice," said the pregnant actress and singer, according to E! News.
Lewis agreed, responding, "That is not nice, you guys."
RELATED VIDEO: Adam Brody: The Best Thing About Working with My Wife Leighton Is …
Brody and Meester rarely discuss their daughter, or even make event appearances together.
"I don't talk about Arlo very much. I am very proud of that area of my life. But I'm also really proud of the show, and of the work I do," Meester told Refinery 29 in 2017. "I think the perception is: You're an ingenue, or you're an icon, or you're a mom. There's no in between."
Speaking to Glamour in September 2018, the actress explained that she still finds a way to relate to her Single Parents character even though she's not a single mom herself.
"Nobody can tell you what parenthood is going to be like," she said. "You think you know, and then it's just so hard. I feel so, so lucky that I have help and a husband. I feel stable, but there are so many people who don't have that. In a really tender way, Single Parents explores how parenting is an emotional roller coaster."