WATCH | Chrissy Teigen lets slip she's having a boy: 'best gender reveal ever'

US model Chrissy Teigen has accidentally revealed the gender of her unborn baby, a move fans have hilariously labelled the “best gender reveal ever”.

Teigen, 34, let slip the good news in one of the videos she posted to her Instagram stories on Thursday.

The mom of two was updating fans on complications around her current pregnancy, which have forced her to be on bed rest. 

Teigen has a daughter Luna and son Miles with her singer husband John Legend.

“Hello friends ... I just wanted to update you ... my placenta sucks. It's always been kind of like the bad part of my pregnancies with Luna, with Miles. It just stopped feeding him [Miles], stopped taking care of him, I was like just stealing all his food because I was getting huge but he wasn't growing at all so he had to come out early and Luna had to come out early.

“Anyways, it's super weak. It's so weird because the baby is really healthy, he's big, he's probably...oops,” Teigen said as she realised the slip-up.

The Cravings author seemed unfazed by the accidental reveal however, simply laughing it off and captioning it “hahahahaha, might as well tell you”, before continuing with the health update.

Fans congratulated the model on the news while quipping that it was the “best gender reveal ever”.