The 32-year-old shared the news on Instagram, captioning the sweet photo: Welcome Arnold Martin Kavalee 💙👶🏼.
Hall, who is married to funnyman Ed Kavalee, announced in February she was pregnant.
The fitness star opened up about earlier this year about potential baby names for their first born.
"We don't know the gender of our baby yet so we have a shortlist for a boy or a girl," Hall tells WHO. "Ed keeps joking he wants to call the baby Hashtag."
Hall revealed that Kavalee has been preparing for fatherhood by spending time with her younger brother and reading a lot. "But he's such a loving wonderful hands on husband that I think being a parent will come naturally to him," she said. "All you have to do is love them, right?!"
This article originally appeared on WHO.