The Irishwoman, who wishes to remain anonymous, had fallen pregnant before arriving in Australia.
Irish citizens on 457 visas are ineligible for Medicare, unlike those from the United Kingdom.
Like other nationalities, Irish 457 visa-holders are required to arrange private health insurance.
The pregnant woman became concerned when private health insurer IMAN said it would not cover costs during her pregnancy because she had been a policyholder for less than 12 months.
Irish health insurers also apply a 12-month waiting period before covering pregnancy care. But the woman learned from a major public hospital in Sydney last week that all her care would be covered.
The hospital’s patient liaison officer told the woman the public system was obliged to treat pregnancy care as if it were a medical emergency.
“Some subclass 457 visa holders may have access to Medicare under reciprocal health cover agreement (RHCA) arrangements with other countries,” said the Department of Immigration.