Structural engineers are checking a NSW home after a balcony gave way and a baby boy tumbled to his death.

A 43-year-old woman and her three-month-old son fell from the second-storey balcony at Niagara Park, on the Central Coast, on Sunday afternoon.

Police say a steel panel barrier on the balcony gave way as the mother, holding her baby, stepped back on to it.

It is understood the mother fell more than a metre onto the garage roof below while the baby continued to fall about 4.5 metres onto the driveway.

The baby boy was airlifted to Westmead Children’s Hospital with critical head injuries and later died.

The mother was taken to Gosford Hospital with back and torso injuries.

She is in a stable condition, a hospital spokeswoman said.

Gosford City Council engineers were sent to the Narani Avenue home on Monday.

Gosford Police Superintendent Daniel Sullivan said the fall was being treated as a tragic accident.

“We don’t rule anything in or out and we make sure every single aspect is looked at,” he told reporters.

“But in this particular incident at the moment our priority is on that structural integrity.”