I was talking about the book, Son of Rosemary. I didn’t realize a movie had been made of it.
There was a made for tv movie sequel within a few years of the original: Look What’s Happened to Rosemary’s Baby (1976) (TV)
I went to see a lecture by Ray Bradbury about a decade ago. He saw Rosemary’s Baby when it came out and was soured by the ending. He’d done screenwriting too (as a script doctor, not just adapting his own works) and postulated his own ending.
He didn’t understand Rosemary suddenly “accepting” the coven and offered up his own ending where Rosemary grabs the baby, flees her apartment, and goes to a church to hold up the child. My recollection is now hazy, he had a succinct phrasing to encapsulate how Lucifer was a fallen angel and how God could redeem this child.
But “creepy” ending wins out over profound.