Caitlyn Jenner's eldest child Burt took to social media on 7 July (Thursday) to announce the arrival of his first child with long-time girlfriend Valerie Pitalo. The race car driver has shared an adorable photo of their newborn son on his Instagram account.

The photo shared by the 37-year-old shows Pitalo holding the little one close to her chest while resting in a hospital bed. The baby boy can be seen staring right at the camera lens. He captioned the photo: "She did it!"

Burt first announced his girlfriend's pregnancy in December 2015 by sharing a picture of their baby's ultrasound on Instagram.

"I promised to wait until we had the 'all healthy' update, and we got it yesterday," Burt wrote. "My Lil boy, just chillin... So happy I can't see straight, he can't get here fast enough... Who wants to fab me a stroller with @kingshocks and @gladiatortires like you see at the 1000 every year? #HesSponsoredAndHeDontEvenKnowIt."

Burt is Caitlyn and first wife Chrystie Crownover's son. He is a diehard supporter of Caitlyn's transition.

"Yup all you haters, my dad will still probably whip your ass at 65 with implants," Burt wrote on Instagram in September 2015.

We had a blast today out in Las Vegas! Thanks for the fun @exoticsracing @exrseries #MyDadLooksBeautiful

A photo posted by Burt Jenner (@bjenner) on