American actress Mary McCormack has given birth to her third daughter.

The In Plain Sight star and her husband, Brothers & Sisters producer Michael Morris, welcomed a baby girl on Saturday morning.

The tot joins sisters Margaret, seven, and four-year-old Rose.

McCormack is yet to choose a name for her latest arrival.

In a series of posts on Twitter.com she writes, "It's a girl! She's not named yet... She's so great but I'm biased."