The actors are already parents to Violet, age 3. Reps for Garner and Affleck could not immediately be reached for comment.
The couple married in June of 2005, and had Violet in December the same year. In August, Garner told press that the two of them were "so excited" for their second child.
Both parents will soon be appearing in a slate of films, including Affleck's He's Just Not That Into You and State of Play, while Garner will be in The Ghosts of Girlfriends Past and This Side of the Truth, among other projects.