Oops. Kim Kardashian just accidentally let slip the gender of her third baby.

The Kardashians have been pretty successful at keeping any ~~important~~ baby details under wraps.

After all, no less than two Kardashian sisters are rumoured to be expecting, and even though fans continue to dissect every Instagram post, every Snapchat video and every interview, the world is still unsure as to what is fact and what is fiction.

But when it comes to Kim Kardashian, who is the only sister to confirm she’s expecting a baby, via a surrogate, the details are pretty easy to come by.

Especially when she lets slip the gender of baby number three on a talk show that’s watched by just shy of three million people every day.

LISTEN: How the Kardashians may have us all fooled when it comes to those baby rumours. (Post continues after audio.)

The 37-year-old reality TV star accidentally let the cat out of the bag during an appearance on The Ellen Show while talking about the extravagant, cherry blossom-themed baby shower the family threw over the weekend.

“I thought I really do want to have a baby shower, because I want [Kim’s four-year-old daughter North] to feel that something’s coming, and for her to really understand it,” Kim said.

“So people brought toys and gifts, and she was opening them all up the next day and she said ‘Mum, you know since baby sister is not here, I think I need all of her toys in my room, and I’ll play with them and make sure they are all OK for baby sister’.”

Yes, @KimKardashian did just accidentally tell the world the gender of her baby. pic.twitter.com/clBxCKPvAL

— Ellen DeGeneres (@TheEllenShow) November 15, 2017

DeGeneres was quick to point out that Kim had spilled the beans about the gender, and the star smiled and confirmed the news.

Kim also joked that she was nervous about how her son, Saint, who turns two in December, would react to the sudden appearance of a new baby sibling.

“I don’t know if my son gets it yet. Especially since I don’t have the belly it is a different experience,” Kim admitted.

Yeezy Wave Runner 700 ????

A post shared by Kim Kardashian West (@kimkardashian) on Oct 18, 2017 at 9:11am PDT

“I said to my sisters, ‘Would I be really creepy if I just had someone dress up like a big stork and drop the baby off at the front door?’ Isn’t that what we heard when we were little?”

Ellen said the suggestion would probably “mess [Saint] up real bad”.

Her surrogate is thought to be due to give birth towards the end of the year, so at least there’s still a few weeks to come up with the perfect way to bring baby home.

With AAP.