Kris Jenner is keeping tight-lipped regarding daughter Kim Kardashian West's forthcoming addition to the family.

Kris Jenner

Kris Jenner

The 64-year-old matriarch is set to become a grandmother for the 10th time in May, as the 38-year-old reality star and her rapper husband Kanye West are expecting their fourth child - their second via surrogacy after daughter Chicago was born in January last year.

Kris was recently quizzed on their "expanding family", but appears to be waiting for the couple to share their baby news.

When 'Extra' host Mark Wright asked: "It looks like [your family] is expanding, Kim and Kanye having another baby", Kris replied: "Well ... it's always a full house!"

Kim, 38, and Kanye, 41, have "just recently" started to share their baby news with their family, and the 'Keeping Up with the Kardashians' star is said to be planning "some sort of shower" to celebrate.

An insider said recently: "They just recently began sharing the news with friends that they were having a fourth. They've been so busy with their three kids and the holidays they haven't had a lot of time to do anything else.

"Kim will have some sort of shower to celebrate. It's a different experience for Kim when she isn't pregnant. But she's happy she has been through this before and knows what to expect. She had such a positive experience the first time and is really thrilled to be able to do this again this way."

Meanwhile, the couple - who also have North, five, and Saint, three, together - are starting to buy "everything" they need for their fourth child.

Despite already having three other children, sources say the pair are stocking up on new clothes and baby supplies, as they "don't really do hand-me-downs".

A source said: "They don't really do hand-me-downs, so each baby is like their first. They're buying everything they need for him, and Kanye insists they go top-of-the-line for everything. So they've been shopping."