The couple, who tied the knot in 2012, already shares Calvin, 4, and Oliver, 1. Dreyer shared the news with a pre-taped video of her and her oldest son making cinnamon rolls.
The mom-to-be showed off the yummy treats, asking her son if they should "check out this bun in the oven." It was Calvin who officially spilled the pregnancy news, though, adorably declaring, "I'm having a baby!" as his mom rested her hand on her growing bump.
Dreyer told her fellow Today stars that she's not due until November, adding that her husband is "over the moon" about their newest addition.
"It turns out we really enjoy having kids," Dreyer said. "Calvin and Oli, they're so much fun. We're like, 'Let's try for a third.' It wasn't happening and we said, 'Let's forget it. Let's move on.' And then of course, surprise!"
"When we first got married, we thought maybe one day we’d have kids," she added. "But then we became obsessed with them... You just realize they’re the best things in the world."
During the third hour of Today, Dreyer shared that the baby on the way will be a boy, making her mom to three sons. "It’s fun to add another boy to the mix!" she said. "I don’t have to add any toys!"
Dreyer has previously been open about her infertility struggles, revealing in 2019 that she'd miscarried.
"I see Calvin with other kids and I see how loving he is. My friend just had a baby, and he held her and it's just so sweet. And I want to give that to him," she said at the time. "I just want people to know that, yeah, I'm kind of going through it with you. I don't know where this ends."
Dreyer also shared her plan to "go all-in on the IVF" to have a second child, but she got pregnant before she could start that process.
"The day I was going to start my IVF -- I had all my medicines, I brought it to the Kentucky Derby with me -- the doctor calls and says, 'Don't take anything, you're pregnant,'" she recalled in July 2019, just months after opening up about infertility. She welcomed baby Oliver in January 2020.
Watch the video below to see how Dreyer announced her second pregnancy.