Kim Kardashian West. Picture: Instagram

Kim Kardashian West accidentally leaked the news she was expecting a fourth child via a surrogate when she was drunk at her family Christmas party.

The 38-year-old beauty rarely touches alcohol and admitted the fact she was so loose-lipped at her family's Christmas party last December that she let slip to "multiple people" she and husband Kanye West had a surrogate carrying another baby for them was one of the reasons why.

In a bonus clip from the last season of "Keeping Up with the Kardashians", Kim told her sister Khloé Kardashian, mother Kris Jenner and Scott Disick: "I told someone at Christmas Eve and I don't remember who I told 'cause I was drunk."

Scott, 36, asked: "Multiple people? Are you upset?"

Kim laughed and replied: "No, 'cause I mean, it was my fault. That's why I don't drink."

The "Keeping Up With the Kardashians" star didn't let allowing her secret out to upset her because she and husband Kanye West were so "excited" about having a sibling for North, now six, Saint, three, and Chicago, 18 months.

She added: "I'm so excited."

But Kim admitted she was initially worried about being a family of four.

She said: "At first I was having so much anxiety, just because I'm going to be a mom of four."

Scott interrupted and joked: "Look at your mom, she's got 19 kids. She's not stressed."

Mother-of-six Kris quipped: "Yeah, I want to kill myself."

The family welcomed son Psalm into the world in May and Kim recently praised the tot as being her "best baby".

She wrote on Instagram last month: "My little man is the sweetest ever! He's honestly the best baby. Sleeps through the night and by far my most calm. How did I get so lucky?"

The reality star recently insisted she's not looking to have any more children because she can't "handle" more than four.

She said: "I LOVE my babies so much but 4 is all I can handle with how busy I am, and each one of my babies needs so much attention."