McCarthy, 48, and Wahlberg, 51, who both have grown children from previous relationships, "used to say their family is complete," says the source. "But now they're telling friends they want a baby together."
According to the source, McCarthy's been feeling "her maternal instincts kicking up a notch," and Wahlberg's warmed up to the idea of expanding their blended brood now that the kids are older. Given McCarthy's age, "she's keen to make this happen sooner rather than later, so they may hurry and go the IVF route," continues the source.
"They'd love to have a baby girl, and Donnie says he hopes she's got Jenny's baby blue eyes." She'll certainly have her pick of '90s lullabies!
The couple started dating in 2013 and tied the knot one year later at Hotel Baker in St. Charles, Ill.
Since then, the pair revealed what makes their marriage work. "We don't really fight, we just get quiet and go to our neutral corners," Wahlberg admitted on Watch What Happens Live! in October 2017. "We have a rule — no makeup sex."
"It's very hot and sexy — and it drains your brain!" McCarthy admitted.
"We call it 'hold the light,'" Wahlberg revealed. "So, if one of us is in a bad way we kinda count on the other one to hold the light. So, if I'm in a bad mood or she's in a bad mood, it's like, 'don't engage.'"
McCarthy added, "Defense is the first act of war, we tell ourselves. It's a real therapeutic way to realize what's going on now that we've brought in from the past."
In August, the blonde beauty couldn't help but gush over the singer. "The love, light, and compassion my husband radiates daily, is the very reason I worship the ground he walks on. Happy Anniversary, my love. I’m truly the luckiest girl in the world. I adore you. ❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️," she captioned a video from their wedding day on Instagram.