"I couldn't be happier," Richie tells PEOPLE. "The only thing you want is for your kids to be healthy and happy, and they are. I'm right where I belong."
In an interview at their home in Laurel Canyon in Los Angeles, Richie, 28, and Madden, 30, her boyfriend and front man of the band Good Charlotte, say they are deprived of sleep, but grateful their daughter Harlow is now fawning over a baby brother.
"I'm glad I had a girl before I had a boy," says Richie. "She just loves him so much." Adds the children's proud papa, "She's very gentle with him."
For much more on Richie and Madden's expanding family – including the decision to name their baby boy Sparrow, how Richie's second pregnancy was different from her first, and how she's losing her baby weight – pick up the latest issue of PEOPLE, on newsstands Friday. (Save a dollar on the new issue. Click here for coupon.)
PeopleTV Archive: Watch Nicole’s Changing Look