Two men, aged 37 and 47, and a woman, 29, are arrested on suspicion of concealing the birth of a child.
Three people have been arrested after the bodies of two babies were found at a home.
Officers were called to a house in Wildmill, Bridgend, just before 20:00 GMT on Saturday.
Two men, aged 37 and 47, and one woman, 29, have been arrested on suspicion of concealing the birth of a child.
Supt Marc Attwell, of South Wales Police, said the incident was “distressing” and appealed for anyone with information to contact the force.
“There will be a visible police presence in the area as extensive inquiries continue over the weekend and we encourage anyone with information or concerns to talk to officers,” he added.
All three suspects remain in police custody.