Kim Kardashian West is "freaking out" about having a fourth child.

Kim Kardashian West

Kim Kardashian West

The 'Keeping Up With The Kardashians' star is set to welcome another baby into the world, via a surrogate, and Kim admits she is incredibly nervous about the prospect of adding to the family's brood.

Talking to sister Kylie Jenner about the news on the family's E! reality show, she said: "I'm low-key freaking out. I didn't think it was going to happen. I thought like, 'Oh, it probably won't even take.'"

During the show, Kanye West - with whom Kim has North, five, Saint, three, and Chicago, 14 months - opens up for the first time on the reality programme in a confessional piece where he likened him and his family to animated superheroes 'The Incredibles'.

He said: "This is my first time doing this. I'm not actually attempting to do good, I just like, part of the reason why I even thought about or considering doing this recording like - what do you call it? this interview - is because of the movie 'The Incredibles'. It starts off with the interviews. The superheroes are giving interviews. The wife got a big butt and I just see our life becoming more and more and more like 'The Incredibles' before we can finally fly."

Kim previously revealed she is feeling "calm" about her impending arrival, though she was initially "stressing" about welcoming another tot.

She said last month: "I was kind of stressing. My house is so full [but] I heard that parents of four are the most enlightened and calm of all parents."

And sources previously claimed Kim and Kanye had always wanted a "big family" and are blessed to have an "incredible gift" on the way.

They said: "The couple has always wanted a big family and their first time with surrogacy went so well, they decided to do it again. The couple is excited to welcome such an incredible gift in 2019. They've also talked that after this child, they are most likely done having kids."