A Sydney hospital says it wasn't understaffed at the time a woman was forced to give birth on her own and hasn't received a complaint from the new mother about her care.

The NSW government's budget cuts have been blamed for the "incredibly distressing" incident in the early hours of Wednesday morning.

The Mount Druitt woman was reportedly forced to take painkillers from her own handbag to ease the pain of labour in the maternity suite at Blacktown Hospital.

She gave birth to a daughter before waiting up to 10 minutes before nursing staff arrived, the Nine Network reports.

"This is an incredibly distressing case and the health minister needs to explain how on earth this was allowed to happen," said opposition health spokesman Andrew McDonald.

He said other patients in the room came to the woman's aid after she called out for help.

But David Simmonds, acting director of nursing and midwifery at Blacktown Hospital, said the woman had not complained about her care.

"We take all patient complaints seriously. In this case staff have spoken regularly with the patient, however she has not raised a complaint," he said in a statement on Friday.

"We are looking into this matter and, as with all matters, we will investigate it thoroughly."

Mr Simmonds said the birthing and maternity units at Blacktown-Mt Druitt Hospital were well staffed with highly trained midwives.

"The maternity unit had a full complement of staff at the time," he said.

"Birth can be unpredictable and can at times come on quite quickly.

"Staff provided regular monitoring of the patient and offered the best possible care in the timeframe."