Cost for Delivering Baby in Melbourne. Will it covered by the health insurance ? ?

If you haven't had your OSHC insurance since before you became pregnant, it's very unlikely that that will cover your delivery (and perhaps not even your pre-natal expenses) as it would be a pre-existing condition and they're not usually covered by any insurance. You must speak to OSHC urgently and find out for sure. Australian hospital care is very expensive for people without Medicare or insurance cover and there is no way to avoid the expense which would be many thousands of dollars.

You will need to talk to your OSHC because your pregnancy is a pre-existing condition. If you were an Australian citizen and covered by Medicare, your prenatal care plus delivery would be free if you went through the public system. If you decided to go through the private system you usually would have an out-of-pocket charge for some services which could add up to hundreds or even a couple of thousand dollars. If your OSHC refuses to cover this you probably will be up for many thousands of dollars. It is really important that you talk to them now.

i doubt very much the birth will be covered you will have to pay all medical bills yourself also having a baby in australia will not allow you to stay once your visa has expired

ring OSHC and ring Medicare australia, i dont know the number but if you googled it you will get a contact number. i'm sure its not as dire as people make out.