The Switch (I) (2010)
Frequently Asked Questions
That would destroy the whole premise of the movie. Kassie didn't intend to use Bateman's sperm and simply just wanted a baby, she didn't want to pimp her body out; not to mention that Roland was already married, so Kassie wouldn't have wanted to commit adultery.
She was also using a scientific method which is much more effective than sex. If she simply slept with Roland, pregnancy was not guaranteed. (her method is still not 100% effective, but is much more effective than sex)