ET's Will Marfuggi joined the Hills alums, who are expecting their second child together, for the reveal of the sex of their baby. The future mom and dad of two got their answer when blue confetti erupted from the cannons they each were holding.
"It's a boy!" Montag shouted. Soon-to-be big brother Gunner, whom the pair welcomed in 2017, was nearby to bring his parents a blue cake in honor of the big reveal. However, the revelation was especially surprising for the expectant star, who thought she was pregnant with a girl.
"My whole intuition is off," she told ET.
"I wanted whatever she wanted," Pratt added.
While Montag would have also loved a girl, Gunner's wish came true. "Growing up I always wanted boys and then recently, I kinda started thinking, I don't know, I kinda want a girl and having one of each," she said. "For Gunner, he really wants a brother, so, you know, ultimately I want what would be the best for him and his life."
Though, after the couple spent more than a year trying to get pregnant with a second baby, a healthy child is the ultimate goal. "As long as a human is in her belly, that's a win," Pratt said. "We're way past worrying about a gender in my brain. Thank you, God, there's a baby here."
The pregnant star got emotional as she remembered all the months of struggling before they conceived. "I felt responsible," she said. "I felt like it was, like, my fault... It was really hard to feel like you want something so bad and it's just not possible... There's nothing else I could have done."
Montag elaborated, "I felt like I was older. I felt a little bit maybe broken down with it. I just felt like maybe I missed an opportunity, maybe I made a bad choice."
While she called the experience "one of the biggest challenges" she's been through, the star made it clear she had not lost sight of all that she already had. "I know I'm so blessed and I'm healthy and I have a beautiful son, so I don't wanna sound ungrateful at all because I am so grateful for everything that I have," she said. "At the same time, I was just hoping to have one more chance to be a mom to a little baby and to have that opportunity for my son to experience having a sibling."
As the family awaits their second baby boy, the pregnancy has not been all smooth sailing for Montag. During her first trimester, Montag experienced some bleeding, which made her worry about a miscarriage. However, it turned out to be the result of a tear near the baby that repaired itself. After also being sick on and off for about a month, Montag said she is finally in a good place and in her second trimester. "I'm sleeping better, I'm feeling good," she said.
Plus, her hands are more full this time around. "I have to keep reminding myself that I'm pregnant because I'm so busy," she told ET. "My first pregnancy, that was all I was thinking about and looking at all my apps and reading all the books and we were in Santa Barbara transitioning to L.A. and now I'm just so busy being a mom and running Pratt Daddy Crystals, which is our company that we have, and studying for a real estate exam and cleaning our house and just L.A. traffic, so I'm so busy throughout the day."
Still, she's trying to cherish the experience since it will likely be her last time expecting.
"I need to remember to just slow down, enjoy the time because this might be my last pregnancy -- it most likely will -- so I'm just trying to enjoy it as much as I can and soak it up and remind myself," she said. "But the feelings are coming back and I personally love being pregnant. I think it's one of the most incredible experiences. It's such a miracle. It's such a blessing and so, I just wanna really embrace it."
As for Pratt, his candidness may be comforting to fellow dads with another little one on the way. "I'm not ready because I still don't actually feel ready currently as a father," he shared. "Every day, it's a new day of a journey. I don't think you can get ready. You can pretend, but like, 'Oh, here's another life you're responsible for.'"
While the couple has about five months left until Montag's Dec. 1 due date to prepare, Paramount is also getting ready to birth a new installment of The Hills -- this time with a brand new cast. The working title for the project is currently The Hills: Next Gen and it sounds like it has Pratt's support.
"I think it's the best thing I've ever heard. It's amazing," he said. "I think a cast that deserves to be on television."
While the official cast has not been announced yet, Pratt said he's seen a short list of contenders and their content. "You need to have a cast that wants to be on TV if you're gonna film a reality show," he said, noting that was apparently not the case for the cast of New Beginnings. "I think the younger kids want to be on TV and that energy translates and transmutes into the TV box."