The couple welcomed son Arthur Saint Bleick on Monday, Blair's rep tells Us Weekly. It's the first child for Blair and Bleick, who met while collaborating on Bleick's EVER fashion line. The newborn weighed in at 7 lbs., 12 oz.
"I feel like the luckiest girl in the world," Blair, 39, told Us at her June baby shower, hosted by BFFs Sarah Michelle Gellar, Jaime King, Karen Zambos and Janey Lopaty.
The Cruel Intentions actress -- who ended her two-year marriage to Ahmet Zappa in 2006 and dated her Kath & Kim costar Mikey Day from 2008 until 2010 -- announced her pregnancy in January.