The unidentified representative told People.com exclusively Friday that the 40-year-old actress, who plays Sarah Walker on the ABC drama, is expecting another child.
The Australia-born Griffiths already has a 3-year-old daughter, Adelaide Rose, and a 5-year-old son, Banjo Patrick, with her husband, Andrew Taylor.
In addition to "Sisters," Griffiths has starred in the HBO series "Six Feet Under" and has appeared in movies such as "The Rookie," "Blow" and "Muriel's Wedding."
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