Rihanna is loving seeing her children grow up

She told Extra: "The babies are amazing. They're all getting bigger and I cannot take it. My sons - oh, my God! - their faces are changing. Their necks are getting longer. I love it."

Rocky, also 37, admitted their kids are as "cute as ever", while he revealed their two boys are "getting along" better than he expected.

He said: "I'm surprised that the older two getting along as much as they are, you know? Usually, you know, for them to be so close in age, they fight a lot, but... happy family."

And a source previously explained that the couple always wanted to have kids who were "close together in age".

The insider told PEOPLE magazine: "Rihanna has always wanted a big family, so she couldn't be more excited. Rihanna and Rocky are thrilled to be growing their family and they can't wait to give their boys another sibling.

"They wanted to have their children close together in age, so that they could grow up together and share a close bond.

"They feel so blessed and are so grateful for this next chapter in their lives. It's a very special time."

Another source previously shared that Rihanna is "all about motherhood" now.

The chart-topping singer has enjoyed huge success in the music and fashion industries, but motherhood has become her firm focus in recent years.

A source told the same outlet: "She brings the kids on every trip, including work trips. The kids come with her everywhere. She never complains that she's tired. She seems to just love life."

Rocky has also been hugely "supportive" of Rihanna since they became parents for the first time.

The insider shared: "They're doing a great job raising their kids. He's very supportive of Rihanna too.

"They're both extremely driven and hard-working. He's the same way - you'll never hear him complain. They're amazing together. Rihanna truly seems the happiest."