The Knocked Up spin-off focuses on married couple Pete (Paul Rudd) and Debbie (Leslie Mann) a few years after the events of the first film.
Melissa McCarthy and Jason Segel appear in the trailer for This Is 40, which takes a lighthearted look at the ups and down of a middle-aged, married couple.
"It's about getting older," Mann told the LA Times earlier this year. "What the hell happened? Am I making all the right choices? Is this where I'm supposed to be? Is this it?
"All of those dreams that you had when you were young, all of the possibilities, when you lock into marriage and kids, do the possibilities dwindle or go away?"
Megan Fox, Lena Dunham, Chris O'Dowd, John Lithgow and Annie Mumolo also star in the movie, which is Apatow's first directorial effort since 2009's Funny People.
Watch the trailer for This Is 40, due out on December 21, below: