Gladesville resident Christine Thomas told police she was pushing her son in a pram along Timbrell Drive, Rodd Point just before 10.30am when a man approached her and began tugging on the pram.
Police said Ms Thomas wrestled the pram off him and the man ran off after a bystander intervened.
She told parent blog Kidspot: “I just remembered thinking, what am I going to do if he gets my son? How am I going to stop him?”
The man was described as being of average height and build. At the time he was covered head to toe in clothing; including a blue hooded jumper, pants, black gloves and had a NRL ‘Bulldogs’ scarf wrapped around his face.
Burwood police are investigating and anyone with information is asked to contact Crime Stoppers on 1800 333 000.
They would like to speak with the male bystander who assisted the woman. He was riding a pushbike at the time.