Jen announced her pregnancy in August 2011, but they had kept the sex of the baby a secret from everyone until today.
She did however hint she was having a boy. "It would be so weird to have a boy," the actress told Ellen DeGeneres, but also said the experience would be "cool and different."
And just last month she told Jay Leno: "I would have thought [he wanted a boy]. At first...I really thought so," the Arthur actress told Jay Leno in January. "And then [Ben] kind of said, 'Well, we have girls. We know how to do girls. My girls love me. I'm the big guy in the house.' So, now I'm not sure."
I'm pretty excited about her giving birth, I was really starting to think Jen was just having back to back babies, it seemed like she had been pregnant on for 18 months. Seriously, I was uncomfortable for her.
So what's his name? Your guess is as good as ours. They haven't released any info about their new baby boy just yet, but if big sisters Seraphina, 3, and Violet, 6 have any say, he's going to be named after a Disney flick. "[They suggested] Donald Duck, Minnie Mouse Affleck," Jen joked. "And then they moved on...[to] Peter Pan, Captain Hook, Smee."
Stay tuned for more info!