Kim Kardashian West forgot to tell Scott Disick she was having another baby.

Kim Kardashian West

Kim Kardashian West

The 37-year-old reality star and her husband Kanye West welcomed their third child, a daughter named Chicago, into the world last month when she was born via surrogate mother, but in a preview clip for an upcoming episode of 'Keeping Up with the Kardashians' - which was shot before Chicago's birth - it seems she forgot to tell one family member.

In the clip, Scott - who is the former boyfriend of Kim's sister Kourtney Kardashian, with whom he has Mason, eight, Penelope, five, and Reign, three - was confused when he paid a visit to Kim's home to find her decorating the nursery for her impending arrival.

He says: "I'll be quite honest: I don't even know what this room is."

To which Kim, unaware of her blunder, replied: "Nursery. So like the little open tub, crib ..."

Scott then asked: "Do you really think you need to worry about redoing these cabinets if this is going to be a nursery for a kid that you don't even have? Are you pregnant?"

Kim - who also has four-year-old daughter North and two-year-old son Saint with her spouse - originally thought Scott was joking, before realising she hadn't told him she was expecting a third child.

She said: "Is this a joke? Do you not know we're having another baby? Scott, we're having a baby in like a couple of months. I'm dead serious. I swear."

The beauty then clarified that she wasn't carrying the child herself, after Scott appeared more confused by the situation.

She added: "No I'm not [carrying the baby]. We went the surrogacy route. I never had this conversation with you? I swear I'm not joking with you. Scott, I swear I'm not joking with you."

Chicago West was born on January 15, and Scott has yet to publicly comment on the news.