Two men and a woman were arrested on suspicion of concealing the birth of a child.
Three people have been released on bail after the bodies of two babies were found.
Officers were called to a property at Maes-y-Felin, Wildmill, Bridgend county, on the evening of 26 November.
Two men, aged 37 and 47, and a woman, 29, were arrested on suspicion of concealing the birth of a child.
South Wales Police continue to investigate the discovery of the bodies of two babies.
The police confirmed that detectives were conducting several lines of enquiry in relation to the discovery of the bodies of two dead babies. This includes holding a number of scenes, including properties, so that enquiries can be made.
For guidance, one of the scenes was released yesterday and the other should be released later on.
Det Supt Darren George said: “My thoughts remain with anyone affected by this traumatic incident.
“I am are aware of the impact this incident has had on the community and would like to thank witnesses and local residents who have come forward and worked closely with us over the last few days.
“This is a complex and sensitive investigation and there has been an increased police presence in Wildmill since Saturday, this will continue over the coming days as enquiries continue.
“We know this update will impact on the local community where this incident happened and beyond, and I’d encourage anyone with concerns or worries to speak to their local Neighbourhood Policing team.”
South Wales Police have appealed to anyone with information to get in touch.