Police have released a picture of the newborn boy found abandoned in an east London park on Sunday.
Officers hope the picture of the baby will encourage his mother to come forward.
Police said they were "growing increasingly concerned" about the child's mother and want to reunite her and her son.
The baby, named Harry by medical staff, was found wrapped in a white blanket in a bush near to Balaam Street, Plaistow.
Det Insp Ian Baker, leading the inquiry, urged Harry's mother to come forward.
"Baby Harry is doing well under the care of hospital staff, but we are very worried about his mother.
"If you see this, please come forward and let us know you are safe.
"Little Harry needs to be reunited with his mother.
"We would urge anyone else with information, or who saw anything out of the ordinary in the Balaam Street area on Sunday morning, to please come forward," he said.