Chock-full of ABBA pop hits and released in 2008, the first movie musical in the franchise took place as the characters prepared for their wedding on a tiny Greek island and Sophie tries to figure out who of her mother Donna's three former suitors is the father she never knew.
The original film ends with Sophie and Sky ultimately deciding not to tie the knot, choosing instead to travel together, while Donna, played by Meryl Streep, weds her long-lost love Sam, played by Pierce Brosnan.
Thursday's preview of the sequel shows Sophie telling Sky: "I've never felt this close to my mother. In the exact same place she was all those years ago. Only this time, we know who the father is."
"You're pregnant?" Sky asks.
"Yeah, I am," a happy Sophie responds.
There is no indication how long it has been since Sophie and Sky have seen each other or who is the father of her baby.
Streep's Donna is seen in flashback in the trailer for the follow-up, but it is unclear if she is still alive. Her co-stars from the original -- Brosnan, Colin Firth, Stellan Skarsgard, Christine Baranski and Julie Walters -- are all seen in the present. Cher also makes an appearance as Sophie's stylish grandmother.
Seyfried and Cooper dated in real life 2008-10. She is now married to actor Thomas Sadoski and gave birth to their first child, a daughter, last year.