Burt revealed the happy news
on Instagram, sharing a picture of Valerie and their baby. He simply captioned the image: "She did it!"
Burt revealed last December he and Valerie were expecting their first child, a boy, and was relieved everything was "healthy" and progressing well.
Sharing an ultrasound photo, he posted: "I promised to wait until we had the 'all healthy' update, and we got it yesterday.
"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.(sic)"
Burt has recently spoken of how since his father transitioned from Bruce to Caitlyn Jenner, they had bonded "more now than ever" and he thinks the 'I Am Cait' star is a "better person" since undergoing a gender reassignment.
He said: "There's been some trade-offs, I'll admit that. But she is a better person. Honesty is always the building block for any relationship, and at least we have that now."
Caitlyn will become a grandparent again later this year as her daughter Cassandra - who she also had with Chrystie - is expecting her third child, a boy, with husband Mark.
The 66-year-old reality TV star also has sons Brody, 32 and Brandon, 35, with second wife Linda Thompson, who she was married to from 1981 to 1986, and daughters Kendall and Kylie who are aged 20 and 18 years old respectively, from her third marriage to Kris Jenner, which ended in 2014.
