Pregnant women considered "non-residents" have paid more than $3.3 million for births at New Zealand hospitals in the past five years.
And in Auckland, where new mums have paid back at least $1.7 million for the delivery of their babies, there have been cases of fraud by non-resident women trying to get free care.
The figures were released to the Herald under the Official Information Act as Canada grapples with a "birth tourism" problem.
Here Auckland's three district health boards - Auckland, Waitemata and Counties Manukau - were the only DHBs of 20 surveyed that confirmed cases of non-residents using another person's identity to get a free birth or access free care elsewhere in the DHB.
In total there were 4682 births to non-resident women across the country between 2013 and 2018.
But some of those women were eligible for free health care because either they qualified or their partner did.
At least $649,184 is currently outstanding from the births and the DHB with the highest number of births was Counties Manukau with 730.
Counties Manukau DHB said it could not break down invoices solely for deliveries but the total amount invoiced for maternity services provided to non-residents during the past five years was $3.1m.
The most expensive birth was $56,533 at Bay of Plenty District Health Board and the least expensive was $1401 at Waikato DHB.
In the Bay of Plenty case the mother had so far paid back $49,053 and payments were still being received.
Some births cost more than others because of complications involving extra clinicians such as theatre staff or the need for a baby to have neo-natal care after delivery.
The highest amount paid back to any one DHB by 254 patients was $948,869 at Waitemata DHB where $209,763 was still owing.
Women were allowed to pay their deliveries off in instalments and DHBs said they did not take legal action against women who failed to pay.
Instead they sold the debt to debt collectors who kept up to 25 per cent of the amount recovered.
DHBs said they never turned away an expectant mum at the point of labour.
"We have a duty to treat and provide care - and then to determine/confirm eligibility," said the then Counties Manukau DHB acting chief executive, Gloria Johnson.
At Waikato District Health Board 73 non-resident births cost the DHB $582,496 with more than $216,000 outstanding.
The most expensive birth there, $25,654, had not been paid and was handed to a debt collection agency.
Capital and Coast DHB in Wellington had collected $365,275 for 92 non-resident births and there was $145,252 remaining to be paid.
Canterbury DHB registered 2484 non-resident births in the timeframe but said only 89 were not eligible and so far 47 had paid back $220,294. A further $17,938 was outstanding.
DHBs said there was no issue of "birth tourism" in New Zealand, where mothers give birth here to claim citizenship for their child, a rising phenomenon in other countries.
That's because you are born a New Zealand citizen only if at least one parent is already a citizen or permanent resident.
Kiwis born here before 2006 are automatic citizens.
In Canada the practice came to a head in the case of Yan Xia who gave birth at Richmond Hospital in British Columbia in 2012.
Something went seriously wrong and it was months before Yan, a non-resident of Canada, and her child were discharged, leaving behind a large hospital bill.
With interest, it now stands at almost C$1.2 million ($1.3 million).
A lawsuit was filed in April in pursuit of the unpaid money.
In New Zealand no fraud hot lines had been set up to catch non-resident health care cheats though there is a Ministry of Health "integrity line" where anonymous tips relating to health care fraud can be reported.
People eligible for free public health care in New Zealand include citizens, permanent residents, Australian citizens and work visa holders who have been here two years, young people in the care of an eligible person, interim visa holders, New Zealand Aid Programme and Commonwealth scholarship students, foreign language teaching assistants and refugees.
Top five DHB non-resident birth repayments
1 Counties Manukau $3.14m (*includes all maternity services) 730 births
2 Waitemata $948,869 254 births (*152 invoiced)
3 Auckland $771,606 170 births (*125 paid or invoiced)
4 Waikato $365,684 73 births (*47 paid)
5 Capital & Coast $365,275 92 births (*62 paid)