Federal Health Minister Tanya Plibersek says an incident where a woman was forced to deliver her own baby in a New South Wales hospital should never have happened.

The woman, identified only as Kristy, told Channel Nine that she had to give birth at Blacktown Hospital in western Sydney with no medical help, after being asked to leave the hospital's birthing unit and being put in a ward bed.

She says her calls that her baby was coming were ignored and she gave birth in the bed.

Ms Plibersek says the incident should never have occurred.

"The New South Wales Health Minister has to apologise to that woman and explain why it's happened," she said.

"It's not acceptable to give birth without assistance in a hospital.

"It's just not acceptable."

The State Opposition's spokesman Andrew McDonald agrees, and says there were clearly not enough staff to respond to the woman's cries for help.

Dr McDonald blames a policy of not replacing staff who leave.

"This is clearly unacceptable care. This is a very lucky near-miss and tragedy was only just averted," he said.

"You have to take notice of near misses like that because the next time you won't be as lucky.

"It is quite clear that this is unacceptable.

"The person responsible is the Minister for Health and she needs to take responsibility for the care."

Investigation begins

State Health Minister Jillian Skinner has issued a statement saying the Western Sydney health district is investigating.

Blacktown Hospital's nursing and midwifery director, David Simmonds, says the maternity unit did have a full complement of staff.

And the hospital's general manager, Andrew Newtown, says the woman did not tell staff she had complaints.

"We do take all patient complaints seriously," he said.

"In this case, staff have spoken regularly with the patient, however she has not raised a concern or complaint about her care.

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

"I'm pleased to say that the mother and baby are both healthy and doing well."