The Stranger Within (1974)

Who is the father of Ann Collins’ baby? Her husband had a vasectomy years ago. And Ann hasn’t been with another man. Even more mysterious: as the baby grows inside her, Ann begins to change. She is beset by strange illnesses, pours tablespoons of salt on her food, turns the thermostat to 50 degrees, speed-reads academic tomes. But much bigger shocks are yet to come. Barbara Eden stars in this hypnotic, swiftly paced blend of horror and sci-fi from Richard Matheson, the popular and prolific writer who also penned the novel I AM LEGEND and several notable THE TWILIGHT ZONE scripts.