Kanye West and Kim Kardashian West. Picture: Instagram

Kim Kardashian West surprised her husband Kanye West with a surprise wedding vow renewal after their son Psalm was born in May.

The high-profile couple tied the knot in a lavish ceremony on May 24, 2014, and to mark their five-year anniversary and the arrival of their fourth child, who was born in May 10, 2019, Kim decided to surprise her rapper husband with a vow renewal.

During Sunday's episode of "Keeping Up with the Kardashians", Kim - who also has North, six, Saint, three, and Chicago, 17 months, with the 'Jesus Walks' star - told Scott Disick: "I think it's so special that all four of our kids are here.

"It'll just be really sweet, and I'm excited that everyone is coming over."

The actual ceremony wasn't shown, but Kim shared the first line from her speech.

She read: "You are my husband. You are my best friend. My biggest believer and my one true love."

The reality star - who turned 39 on Monday - also shared how Kanye "stepped up" his game after Psalm was born as she opened up about having "anxiety".

She said: "Things are definitely more chaotic like all the time, but I make it a serious point to spend time with him.

"Kanye knows that I've had such anxiety with the new baby and everything going on.

"He's stepped up so much and has been the most amazing dad, playing all the games with the kids and things like that."

The KKW Beauty businesswoman also revealed that she was planning on calling Psalm "Ye" at one point, but Kanye - whose name is often shortened to Ye - "didn't like it".

It was her half-sister Kylie Jenner who suggested Psalm would work well with Saint.

She said: "His name was going to Ye, but Kanye didn't like Ye because Ye it doesn't mean anything.

"We looked up every name in the bible that had Ye in the beginning, and the only name was Yehezkel, and Kylie called at the last second and was like, 'no!' Pslam and Saint sound good together."

Kim admitted having four kids has made her feel "complete" as she gushed about their "amazing" surrogate.

She said: "Our surrogate is so amazing. She had the easiest delivery.

"She pushed literally maybe one time.

"Kourtney and Kanye were in the room with me.

"I feel so complete. I really do feel like four [kids] is the perfect number for me. I feel so full in the best way, but I'm done."