During an appearance Wednesday morning on CBS' The Early Show, the Accidentally on Purpose actress, 37, revealed that she is expecting her second child with husband Bodhi Elfman.
"I have a baby in my tummy – but a real one, not just for my TV show," she shared. "My character's pregnant the whole first season, so I said, 'It's a good time to have another baby, because we won't have to hide it.' "
On the show, Elfman plays a woman that becomes pregnant by a much younger one-night stand, who then moves in with her. Eagle-eyed viewers should keep an eye out for her own burgeoning bump, Jenna jokes.
"By episode three if you look closely once it airs, you'll see ... 'Oh is she a little bloated? Did she have a big dinner?'"
The Elfmans – already parents to 2-year-old son Story Elias – were married in 1995.
Accidentally on Purpose premieres Monday, Sept. 21 at 8:30 p.m. on CBS.