12/29/2008 AT 01:50 PM EST
actress Chyler Leigh is expecting her third child, PEOPLE has learned exclusively.
"They are absolutely thrilled and looking forward to the new addition to their young family," her rep tells PEOPLE.
The actress, 26, and her actor/musician husband, Nathan West, are already parents to two children.
Leigh's pregnancy will not be written into the Grey's
storyline, according to her rep Marcel Pariseau.
Leigh plays "Lexie," the half sister of Meredith (Ellen Pompeo) on ABC's hit medical program. She joined the show
in July 2007.
, Leigh previously starred in the short-lived series Reunion
and That 80s Show
. She also starred in 2001's Not Another Teen Movie.RELATED ARTICLE:
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