Aniston finds her perfect donor in Patrick Wilson. But in a drunken stupor, her best friend (Bateman) accidentally loses the donation, so he secretly makes one of his own.
"The draw to come see this movie is to come see how these guys work their way out of what becomes a pretty complicated and challenging situation," said Bateman.
After giving birth, Aniston leaves town. Seven years later, she returns to New York with her slightly neutrotic son who resembles Bateman.
He has several scenes with supporting player Thomas Robinson, the boy who may be his son.
"He was very sort of even-tempered, talented and kind and he's everything you'd want an adult actor to be at a young age. So I would buy his stock early," said Bateman.
The 41-year-old actor has played a lot of supporting roles in films, so being the leading man in a big-budget movie is a big deal, even if he's trying to downplay it all.
"You know, you wait your turn and even in this case, you know, the bigger, better names were either busy or not interested and it found its way to me. And hopefully I do a good job and they ask me to do more. It's simple math," said Bateman.
"We're coming up with a package rate. We haven't settled on a number, but I think Hollywood's going to like it," said Bateman.