Police said the baby died on Friday, despite the efforts of medics. It comes after a man and woman were charged following the incident.
A three-month-old boy who was found unresponsive at a house in Seacombe, Wirral, has died.
Officers were called to reports of concern for a child at a property in Percy Road at around midday on Sunday, Merseyside Police said.
The baby was taken to hospital, where injuries were found on his body. His condition was described as "critical".
A police spokesperson said on Friday: "The boy received treatment in hospital but despite the efforts of medical professionals, was sadly pronounced deceased this afternoon".
A man and woman were charged after officers attended the property on Sunday.
Klevi Pirjani, 36, and Nivalda Santos Pirjani, 33, both of Seacombe, are accused of causing grievous bodily harm and wounding with intent.
They were remanded into custody and are due to appear at Liverpool Crown Court on 23 December.