Caitlyn Jenner responds to Kylie Jenner's baby news with moving message.

Caitlyn Jenner has responded to the news of her daughter’s first baby with a public message on Instagram.

Writing alongside an image of Kylie, 20, as just a baby, Caitlyn wrote:

“My daughter just had a daughter. It’s amazing to be by your side through this journey. She’s SO beautiful already. Can’t wait to watch her grow. Throwback to my baby, as a baby.”

A post shared by Caitlyn Jenner (@caitlynjenner) on Feb 5, 2018 at 5:09pm PST

The 68-year-old’s message comes just days after her ex-wife Kris Jenner shared a similar sentiment.

“God is SO good!! I am so excited and thrilled to welcome another precious baby girl to our beautiful, ever growing family. We are blessed beyond belief!”

Though rumours of her pregnancy had been swirling – with exceptional vigour – since September last year, it was only this weekend that Kylie confirmed what the world knew to be true: She had been pregnant, and now she has a baby.

“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. 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,” she said in a statement shared on Sunday.

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“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,” she continued.

“I appreciate my friends and especially my family for helping me make this special moment as private as we could. My beautiful and healthy baby girl arrived February 1st and I just couldn’t wait to share this blessing. I’ve never felt love and happiness like this I could burst! Thank you for understanding.”

The family are yet to reveal the baby’s name.