Kylie Jenner says 'I'm pregnant' at Khloe Kardashian's birthday

Kylie Jenner may have let slipped she is expecting another baby. Photo / Instagram

Kylie Jenner has said "I'm pregnant" in a video taken at her sister, Khloe Kardashian's birthday.

The 21-year-old billionaire can be heard in the video declaring she is pregnant as the camera pans across a doughnut tray.

Jenner is already the mother of 18-month-old Stormi with her rapper boyfriend, Travis Scott, 28.

She has made no secret of her wish to expand her family.

In April she posted a picture on social media for Scott's birthday, saying "Let's f**k around and have another baby!"

Jenner has also said on Snapchat that she "wants another girl".

Jenner was super secretive during her first pregnancy and didn't confirm the news until the last minute. She had started dating Scott just a month before they fell pregnant.

"My pregnancy was one I chose not to do in front of the world. I knew for myself I needed to prepare for this role of a lifetime in the most positive, stress free, and healthy way I knew how," Jenner said in a video at the time.

"There was no gotcha moment, no big paid reveal I had planned. I knew my baby would feel every stress and every emotion so I chose to do it this way for my little life and our happiness."