Cooks River, Earlwood: Major update in urgent effort for baby delivered along Sydney reiverbank

Fears remain for the safety of a mother and her newborn baby nearly seven days after a placenta and umbilical cord were found on a Sydney riverbank.

Investigators are yet to track down the woman or the child nearly three days after a dog walker found a placenta and umbilical cord on the banks of the Cooks River at Earlwood.

Testing of the material revealed the placenta and cord belonged to a baby boy, police said on Thursday.

Authorities have held fears for the safety of the mother and newborn since it was found on Monday afternoon.

The mother is being urged to seek medical attention at a nearby hospital as police insist the health of her and her son remains their top priority.