Brandon Jenner's family is growing again.

The reality star and his wife Cayley Jenner are expecting their third child together, they announced on Feb. 27.

Their baby on the way—who is due to arrive in August—will join their 4-year-old twins Bo and Sam, 4, as well as Brandon's daughter Eva, 8, from a previous relationship with Leah James.

The couple found out about Cayley's pregnancy in December, though Brandon—Caitlyn Jenner and Linda Thompson—already had a hunch. As Cayley recounted to People, 

"When I went to tell Brandon that night as we were getting ready for bed he totally beat me to the punch," Cayley told People. "I had the tests in my pocket and I was going to just lay them down as he was brushing his teeth, but before I could do it, he looked at me and said, ‘So how pregnant do you think you are?' I was floored." 

She added, "We conceived on Thanksgiving, which is so cute and special. I feel so grateful to get to do it all over again." 

And Eva was the first one in their brood to find out about the baby news.

"We wrapped a onesie and gave it to her on Christmas Eve while her brothers were napping, and as soon as she saw the onesie, she knew," Cayley recalled. "She gasped and looked at me with the sweetest, knowing eyes, then lunged across the bed to hug me and said, ‘You're having another baby!'"

 

The pregnancy comes amid a major relationship milestone for Cayley and Brandon. Last month, the pair celebrated their fourth wedding anniversary.

"4 years of marriage, 5 years by your side, 3 kids, 11 chickens, 1 tortoise, 2 dogs, and a whole lot of chores and jobs and messes and chaos and food and stuff," Cayley wrote in a Jan. 21 Instagram post. "But really, just an insatiable desire to show up for eachother, for our family, to serve. I am forever grateful to be your partner in this life, to get to do this with you."

 

Meanwhile, Brandon marveled at the "wonderful family we have created."

"4 years married to my partner in everything," he wrote in an Instagram post of his own. "I'll carry the kids, you carry me."

For the latest breaking news updates, click here to download the E! News App