Police said emergency services were called to the bank of the Cooks River near Wardell Road in Earlwood at 4.30pm on May 27 after evidence was found that suggested a baby had been born there.
”Forensic tests have confirmed the baby born is male,” NSW Police said in a statement.
Officers are still searching for the mother and child.
“Police hold serious concerns for the welfare of the child and his mother,” police said.
“Officers are urging the mother to attend her nearest hospital to receive urgent care for herself and her child.”
The placenta and umbilical cord was found among mangroves.
Earlier in the week Burwood Superintendent Christine McDonald said she just needed to know the mother was safe.
“I need to know she is receiving the support she needs right now.”
She said there was “no judgement” involved in the investigation and no evidence so far the baby had been intentionally harmed.
Police are appealing for anyone in the area with information to come forward.
