Police today said an FIR was registered on Saturday after the victim complained to city's Bhoiwada police that she was allegedly raped by three persons in a car after being kidnapped by them nine months ago at Kansai in Ambarnath township of Thane district.
On the intervening night of Saturday and Sunday, the victim delivered a baby boy at KEM hospital in Parel, police added.
The case has now been transferred to Vithalwadi police station in Thane as the crime allegedly took place in its jurisdiction.
The alleged offence came to light after the victim was admitted to hospital for delivery on Saturday night and she could not provide the name of her husband to hospital authorities.
The doctors advised her to register a complaint after she revealed that three persons had kidnapped her from near her home and raped her in a car nine months ago, police said.
The accused were booked under relevant IPC sections including 376(2)(g) (gang rape), police said adding that further probe was on.