Blessed (2004)

Heather Graham and James Purefoy play a couple who desperately want to have a baby. Unfortunately, she has been diagnosed as infertile, and the couple can't afford the medical treatments that might allow her to conceive. Good fortune appears to be smiling on the couple when they are given an opportunity to receive free treatments at a mysterious fertility clinic. The woman is soon the expectant mother of twins, but as her due date draws nearer, she begins to suspect something is wrong, and that she has become the unwilling victim of a pact with evil.