Officers were called at 12.15pm on Thursday and attended the scene on Norman Crescent, Rossington, alongside the ambulance service.
The baby was pronounced deceased at the scene.
Two women, aged 17 and 45, have been arrested on suspicion of murder and remain in police custody at this time.
Temporary Superintendent Jamie Henderson said: “This is an extremely tragic case and I know the local community, and those further afield, will be very upset to hear about what has happened.
“At this time, our investigation into the circumstances surrounding the baby’s death is in the very early stages and we ask the public not to speculate about the case.
“There is a cordon in place on Norman Crescent in the Rossington area while our officers carry out their work, and therefore we are asking members of the public to avoid the area at this time.”
Police have also reiterated in a statement online
These proceedings are active and the Contempt of Court Act applies to any comments posted on social media. Any material which could prejudice a jury in a future trial is deemed as being in contempt of court and is punishable in a court of law.
Police are appealing to anyone with information which could assist with enquiries into this incident to call 101, quoting incident number 325 of 16 December.
Alternatively, you can stay completely anonymous by contacting the independent charity Crimestoppers via their website Crimestoppers-uk.org or by calling their UK Contact Centre on 0800 555 111.
Date: Thursday 16 December 2021
First Published: 18.30 GMT