Soon after Rosemary meets her Terry's body lies in a pool of blood on the sidewalk next to a car with a bloody, bashed in roof (0:16). Those who knew her argue over whether she might have killed herself. Roman describes her as "deeply depressed every three weeks" (0:17). As the story unfolds we find more evidence for suicide as well as more reason to suspect murder. Concurrently evidence develops on both sides of the question of whether Rosemary suffers from delusions or whether others conspire against her invoking witchcraft or other supernatural activity.
When Rosemary tells Dr. Hill about a "plot against me," he appears to believe her, but betrays her and his own disbelief by contacting the doctor (Sapirstein) she believes conspires against her. She does, however, allow that these events might be coincidental. (1:44, 1:46) Dr. Sapirstein threatens she must cooperate to avoid forcing him to "take you to a mental hospital." Later, when she becomes agitated he approaches with a syringe with "nothing but a mild sedative to calm you down" and injects her arm (1:56). A second injection (2:00). Her husband tells her she suffers from "some kind of hysteria" or "pre-partum crazies."
Reference in When Harry Met Sally