A dead baby found abandoned in a garden with its umbilical cord still attached was stillborn, a post-mortem examination has found.
The white boy was found wrapped in a T-shirt in gardens at Skelton Close in Hackney, east London, on Sunday morning.
Detectives said it was urgent the baby's mother came forward as she was likely to be in need of medical help.
Officers have been making checks at maternity units and homes in the area.
Det Insp Colin Burgess said: "Because the placenta was still attached to the baby's body it is likely that the mother is very poorly.
"At this stage we are very concerned over the physical and mental well-being of the mother and urge her or anyone who knows her to come forward."