"Rhea's very happy," her manager, Liz Dagostino, told the Associated Press.
No further details were provided. However in January Wahlberg told PEOPLE that they had already picked a name for their son: "My dad called me Mike since I was a kid. So in honor of my dad, I think we're going to name him Michael."
Wahlberg, 34, who's one of nine children (including former New Kids on the Block singer Donnie, 36), also has a 2-year-old daughter Ella Rae, with Durham, 27.
Of fatherhood, Wahlberg told PEOPLE last year, "It changes every aspect of your life, and every one for the better."