Pam is married to paper and printer salesman Jim, played by John Krasinski, on the show.
In real life, she has been wed to screenwriter Lee Kirk since 2010 and is pregnant with their first child.
"Pam will be pregnant when the season starts," TVGuide.com quoted Fischer as saying. "Pam and Jim snuck away last season on Valentine's Day, and they had sex. The story is that they conceived this baby at that time and were keeping it a secret until we come back from the summer."