Kourtney Kardashian is having a baby boy

Kourtney Kardashian is expecting a baby boy.

Kourtney Kardashian Source: Bang Showbiz

The pregnant reality star has revealed she is having a son with her boyfriend Scott Disick.

The pair - who are already parents to Mason, four, and two-year-old Penelope - shared the happy news on the latest episode of 'Kourtney and Khloe Take The Hamptons', which aired in America last night.

Recalling the moment they realised what gender their new addition will be, the expectant mother said: "Mason ran in here with the blue stick. There was a red star [for a girl] or a blue star [for a boy]."

Despite Mason's initial excitement, he later revealed how he had been hoping for a little sister.

He moaned: "I wanted a girl."

However, his auntie, Khloe Kardashian quickly soothed him as she reminded Mason of all the fun things he can do with a younger brother.

She said: "Girls don't like aliens and Lego guys. When you have a brother you can say, 'Look at all my Lego guys, brother.' You get to be rough and you can boss him around because you're the older one."

The E! show also included footage which had been filmed by Kourtney's sister Kim Kardashian, which showed the exact moment the entire family found out the good news.

Kourtney - who is due to give birth around the holidays - recently showed off her bump in a nude photo spread for DuJour magazine.

In the latest issue, she shared: "I really feel so comfortable, and almost at my best, when I'm pregnant ... I just feel like it's such an amazing feeling."