Arie Luyendyk Jr. and his wife Lauren Burnham Luyendyk are expecting a baby girl

During the special occasion - which they filmed and uploaded to YouTube and Instagram - Arie admitted he was convinced the baby was a boy.

He could be heard saying in the video: "I think it's a boy. And I thought it was a boy the entire time. If my instincts are wrong, I'm going to be so shocked. I'm wearing blue because I think it's a boy. This pregnancy feels different."

Shortly after the TV personality's prediction, the couple burst a balloon to cause pink, white and gold confetti to explode out of it.

They told their kids: "You're going to have a little sister!"

Alessi, Senna and Lux were able to announce the gender themselves, as they dipped glasses into a cake with pink filling.

The former 'Bachelor Nation' stars announced to the world in March that they are expecting their fourth child.

Lauren shared a photo of her showing off the baby bump on Instagram on March 10, and she captioned it with: "Our last missing piece, coming this September."

It comes after Arie underwent a vasectomy reversal in summer 2024 to try for another child with Lauren.

She said in a previous YouTube vlog: "We said we were done having kids, like, a couple years ago, but I think we're going to do it one more time.

"That sounded funny, like, we're only going to do it one time."

Arie explained: "As you guys know, I got the vasectomy [in 2022] after the twins were born.

"Ever since, I think I rushed it, honestly. It's more on me [and] I think having the twins was hard at first."

Lauren added: "He was like, 'OK, it's happening. We have got do this. And we did. I got on board."

Arie continued: "All of our kids are at the best age right now, and I just felt like, 'Dang it, I think we could do this again.' If we had a singleton, we could totally handle that."

The couple have both insisted that the new baby will be their last.