Caitlyn Jenner has broken her silence on the birth of her fourth grandchild after she was left out of her daughter's pregnancy video.

Kylie, 20, and her rapper boyfriend Travis Scott welcomed their daughter on 1 February and chronicled her pregnancy in an 11-minute homemade film.

Taking to Instagram, Jenner shared a throwback snap of Kylie and a gushing message with her 8.8 million followers in a bid to quell speculation that their relationship had become frosty.

"My daughter just had a daughter. It's amazing to be by your side through this journey," she captioned the snap which shows baby Kylie grinning at the camera - with food smeared around her mouth.

"She's SO beautiful already. Can't wait to watch her grow. Throwback to my baby, as a baby."

As her daughter went into labour in Los Angeles, the former Olympian was in Dublin where she was a guest at the Xpose Benefit Awards.

It was previously reported Jenner was not pleased about Kylie becoming a young mother, with a source telling Hollywood Life: "Obviously, Kylie has more than enough money to ensure that she can pay for help, but Caitlyn still thinks that having a baby will take a huge toll on Kylie's life.

In a lengthy statement to fans, Kylie revealed why she had shunned the limelight as she prepared to become a mother.

"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," she explained. "Pregnancy has been the most beautiful, empowering, and life-changing experience I've had in my entire life and I'm actually going to miss it.

Watch Kylie Jenner's pregnancy video here:

"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.

"Pregnancy has been the most beautiful, empowering, and life-changing experience I've had in my entire life and I'm actually going to miss it. I appreciate my friends and especially my family for helping me make this special moment as private as we could."