The representative confirmed the news to UsMagazine.com Friday.
Blair is best known for her work on the sitcom "Kath & Kim" and the films "Cruel Intentions," "Legally Blonde" and "Hellboy."
She has been dating EVER clothing line founder and creative director Jason Bleick for less than a year, UsMagazine.com said.
Their baby's due date was not reported.
Pistorius testifies he didn't consciously pull trigger when he shot girlfriend
Pregnant Mila Kunis wins 'Best Villain' at MTV Movie Awards