Kim Kardashian West thought her ''life was over'' when she found out she was pregnant.

The 36-year-old reality star - who has daughter North, four, and son Saint, 21 months, with husband Kanye West - was ''hysterical'' when she learned she was expecting for the first time because she'd been warned it would be ''really hard'' to conceive and, at the time, she and the 'Famous' rapper hadn't been thinking about starting a family.

Kim, who married Kanye in May 2014, was in Florida shooting 'Kourtney and Kim Take Miami' when she found out the news.

She recalled: ''I don't even think we thought of kids. Khloe and I had gone to a fertility doctor, and they said they [thought] it would be really hard for me, so I was about to freeze my eggs. And then I randomly got pregnant.

''I remember calling [Kanye] and he thought a family member had died because I was so hysterical. I thought my life was over, [because] I was pregnant. It was so hard for me.

''Obviously it's the best thing that ever happened to me.''

Kim's pregnancy was filled with complications and she even thought she'd had a miscarriage at one point.

Speaking on the 'Keeping Up With the Kardashians' 10th anniversary special, she said: ''It was just a few weeks in, and I was so scared. I mean, at one point I thought I had a miscarriage. I was pretty certain about it.

''I didn't know what was going on. So I flew all the way home on Thanksgiving and the doctor told me, 'There's no heartbeat, you had a miscarriage. Let's get through it.'

''I went in [the next] morning and he's like, 'There's a heartbeat. You didn't have a miscarriage!' And I was like, 'Oh my God, this is a sign.' It was such an emotional Thanksgiving.''

The brunette beauty initially didn't want her children to feature on the family reality show, but softened her stance as time went on because they are ''so cute''.

However, Kim insists they will never be the focus of their own storyline.

She said: ''At first we were like, 'Our kids will never be on!' I said that. 'No my daughter is never going to be on.'

''But she's like, always around me, and she's so cute, so I'm like, 'I just want people to see a little bit!'

''It's never a story revolving [around] them or about them, or anything too personal.''