Selma Blair, Jason Bleick Beverly Hills son Arthur Saint

He's already out and about!

Selma Blair looked perfectly posed as she and partner Jason Bleick took their newborn son Arthur out in Beverly Hills on Saturday.

Arthur was born July 25 -- the little guy was overdue, but mom Selma, 39, wanted to have a natural birth. Check out our exclusive video, in which Selma reveals to us that she was almost 11 months pregnant! Crazy!

And see what she tells us that baby Arthur can already do on his own!

Selma and her bf seem on top of the world -- we even caught them in a loving embrace -- see the pic after the jump!