Ryan's representative, David Lust, told the magazine the 39-year-old actress and her husband, French chef Christophe Eme, are thrilled with the news.
"She is thrilled about the new addition and they are very, very happy," Lust said. "They are beyond excited and are beaming from ear to ear."
The film and TV actress, who already has a 12-year-old son from a prior relationship, is due next March.
The couple married in June at a French castle in Eme's hometown, and now own the French eatery Ortolan in Hollywood.
People said Ryan will soon be on the air again when CBS begins showing the second season of "Shark" Sept. 23.