Jennifer Lopez's 'Back-Up Plan'

J.Lo returns to the silver screen in "The Back-Up Plan," her first starring role since the birth of twins Max and Emme in February 2008 -- and she's opening up to "Extra" about her babies, being a working mom, and losing all that pregnancy weight!

Lopez reveals that she and hubby Marc Anthony want to have more children. "I would love to have more kids. I don't know if we will. I don't know if that's in the cards for us. But we'll see."

Jennifer revealed that she loved staying home with her kids, but was ready to get back to work. She brought little Max and Emme to the set nearly every day. "They've been with me almost every day on the set. I don't think they realize what I do. Once in awhile, they look at the monitor and go, 'Mama.' They're just starting to talk."

J.Lo plays a woman who is artificially inseminated on the same day she meets Mr. Right -- and sports a fake belly bump for the film. "A bunch of us who have babies, we're like, 'It would be great when you are pregnant...you could take it off five times during the pregnancy, only for a half hour. Then you have to put it back on.' That would be awesome. It would be perfect. But you can't."

Lopez admits that shedding the baby weight took hard work. "Just like everybody else, the first big amount of pounds comes off pretty quickly and then you have those last 10 or 20, 15 or 20 that just don't want to go and you have to work really hard and I had to work really hard too. I had to diet and work out. I had to do a lot."

Jen's twins are only 18 months, but the actress laments how fast her little ones are growing up. "They're more than walking now...they're starting to talk. I put Max to bed yesterday...and I said, 'I love you baby. I'll see you tomorrow.' And he was like, 'I love you.'"