The Last Trimester is a 2006 made-for-TV movie starring Chandra West, Jim Thorburn, Matthew Harrison and Lara Gilchrist.
Tracy (Chandra West) and Eric Smythe (Jim Thorburn) are a happily married couple who find it difficult to have children.
Closer to the due date, Gabby starts appearing unstable, openly flirting with Eric, acting scary to Tracy, and destroying their home.
While gardening Tracy stumbles upon a shirt with blood and fears that Eric murdered Gabby to gain custody of the baby.
Eric then puts the pieces together, discovers that Nick was involved with Gabby, and rushes home to find that Tracy has taken off with the baby.
While at the cabin Tracy tries to find out information on Eric's case, and discovers that Nick had a child who died, and he tells her that baby Sarah looks just like her father.