Unfortunately not I think Green Apple for I'm pretty sure that Thailand does not have reciprocal rights with Australia - Skilled – Regional Sponsored (Provisional) Visa (Subclass 475)

And Roelant, one the smaller funds but a reasonable one - Health Insurance, Private Health Cover, Home & Contents Insurance, Private Health Insurance - Australian Unity you may want to try but I think you'll find that most private funds will have that pre-existing condition exclusion and waiting time.

What you may also be able to do if you find a good obstetrician is to have him/her be your attending birth doctor at a public hospital, pretty sure that kind of thing still occurs for many specialists who have private practices also do work at public hospitals or they used to anyway.

That way, the hospital charges would be met by medicare and there may even be an arrangement whereby you can pay something extra to have a private room rather than be in a shared one [not for the delivery of course for that happens in special delivery rooms as far as I know] and then the doctor would charge you and you could get some rebate from medicare.

And I would not know whether travellers insurance covered a pregnancy but no harm in asking!