The 32-year-old actress appeared on Good Morning America on Tuesday to promote her new film, The Rhythm Section, and was asked about having three children all under the age of 6. Lively and 43-year-old Reynolds are parents to 5-year-old James, 3-year-old Inez and a third daughter they welcomed last year.
"It's like going from two to 3,000," she said about the difference between having two children and three. "I mean, we have so many children. It's pretty crazy. We're outnumbered, and it's a lot."
"People say going from two to three, it's the same, you know, it's kind of easy -- those people do not have three kids," she continued to joke. "It is real crazy. But I'm here."
"That day was not my favorite day," she told ET. "I'm not sure if it's the take that's in the movie, because I did shoot 'till the end. I'm the person who doesn't ask for directions and I have a real ego about all that stuff. I was like, 'It's fine, my hand's fine!' After a few days, when my hand just looked like Jell-O, I thought, 'You know, it's time to go to the hospital.'"
For more on The Rhythm Section, which hits theaters on Jan. 31, watch the video below: