Are Ben and Jen expecting a girl? Jennifer Garner appeared on NBC's Tonight Show on Tuesday night, and seemed to refer to her baby as a "she."

"You can just start to feel really pregnant. Like you are the hugest person on the face of the planet. ... And then I felt just bigger and bigger like she ..." Oops. Garner put both hands over her mouth.

"We have one or the other for sure," replied Garner, who is married to her Daredevil co-star Ben Affleck.

The 33-year-old actress stars as Sydney Bristow on ABC's Alias, which returns Thursday for its fifth season.

Garner's pregnancy was written into the show, even though her character is a globe-trotting spy.

"My stand-in has a little bump. My stunt double has a bump, and the other day I walked in, and my stunt double just looked a little different to me and I said, 'Did they graduate your bump?' ... And she said, 'Yeah, we went to a bigger bump.'"

Garner and Affleck were married in June. Their baby is due around Christmas.