The couple - who are already parents to daughter North, four, and son Saint, 23 months - are expecting their third child via a surrogate and the 37-year-old star has now confirmed the gender of their baby, who will be born early next year.
Kim was discussing her recent baby shower gifts when she revealed North is excited about having a sister.
She told talk show host Ellen Degeneres in an appearance airing on Wednesday (15.11.17): ''My daughter is really tricky. We had a baby shower over the weekend, I wanted her to feel something is coming and for her to understand it.
''People brought toys and gifts and [North] was opening them all up the next day and she said, 'Mom, since baby sister's not here, I think I need all of her toys in my room and I'll play with them and just make sure they're all OK for baby sister.' ''
But the 'Keeping Up With the Kardashians star is unsure whether North will be just as excited when she realised how much of her parents time the baby will take up.
She said: ''North is really excited about that. [Having a brother] was a little trickier, so she's excited.
''Let's see if it lasts. I explained to her, 'Four in the morning, when you come in my room, I'll be with baby sister, I have to feed her', so we'll see how it goes.''
The family have begun ''freaking out'' about the fact they haven't yet chosen a name for their new arrival.
Kim admitted: ''We don't have a name. At the baby shower I was like, 'I don't want to play any games, measuring the belly, that won't work out this time. I just want everyone to write a name on a little tile and we'll see if something sticks.'
''We're freaking out. We have no name.''
To try and help Kim, Ellen used her 'Celebrity Baby Name Generator', which suggested Lip-Kit, West, Star, or Pop, and though her guest rejected all the suggestions, she revealed North was particularly keen on one of the monikers.
She said: ''I'm not gonna name her Star, but my daughter picks that name all the time. She's got a toy, it's a momma and she likes to name the toys.
''I said, 'What do you wanna name it?' and she said 'Star. Star West.' She names everything Star. I'm not vibing on it.''
But Kim did explain what she's looking for in a name.
She added: ''It's so hard. I like different names, short, easy to spell, one syllable, that's my vibe.''
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