OTTAWA -- With new research showing that more babies are born in Canada to foreign residents than Statistics Canada realized, the federal government is studying the issue of "birth tourism" in the hope of better understanding how many women travel to Canada to have babies who are born Canadian citizens.

Using numbers from the Canadian Institute for Health Information (CIHI), which captures billing information directly from hospitals, researcher Andrew Griffith found over 3,200 babies were born here to women who weren't Canadian residents in 2016 -- compared with the 313 babies recorded by Statistics Canada.

The finding suggests not only that the numbers are higher than previously reported, but that it's a growing trend, Griffith says.

"(The data) shows the steady growth in the number of babies born in hospitals to women who are residents of other countries, by absolute numbers and percentage, for all provinces except Quebec," Griffith wrote in an article in Policy Options, published by the Institute for Research on Public Policy. "These births total just over one per cent of all live births in English Canada."

A petition tabled recently in the House of Commons by Liberal MP Joe Peschisolido calls on Canada to take stronger measures to end birth tourism, saying it abuses Canada's social-welfare system.

Immigration Minister Ahmed Hussen responded by saying his department has commissioned research to get a better picture of the scope of the issue in Canada.

"While these statistics indicate that this is not a widespread practice, the government of Canada recognizes the need to better understand the extent of this practice as well as its impacts," Hussen said in his response, tabled in Parliament.

The department has commissioned CIHI to perform this research.

The issue of so-called birth tourism has been polarizing in Canada, with the Liberals defending the current law that gives automatic citizenship to anyone born on Canadian soil except for children of foreign diplomats.

Conservative party members passed a policy resolution during their biennial convention this summer calling on the government to end birthright citizenship "unless one of the parents of the child born in Canada is a Canadian citizen or permanent resident of Canada."

Leader Andrew Scheer said at the time one of the goals would be to end the practice of women coming to Canada simply to give birth to a child that will automatically have Canadian citizenship.

Other countries have ended or modified their birthright-citizenship laws, including the United Kingdom, Australia, Ireland, New Zealand, India, the Dominican Republic, Thailand and Portugal. Recently, U.S. President Donald Trump has threatened to end birthright citizenship in the United States, although critics have argued such a change could violate that country's constitution.

Canada did explore changing Canada's existing birthright policy under Stephen Harper's Conservative government. This work ultimately found any change to the law would have significant impacts, according to a senior government official who spoke to The Canadian Press on background.

Many Canadians -- 40 per cent or more -- don't have passports and use birth certificates to prove their citizenship. A change in birthright-citizenship rules would mean they'd need new forms of identification to prove their citizenship and get government services.

A 2013 estimate pegged the cost of changing the rules at $20 million to $30 million, plus $7 million in extra costs for the federal government every year, the senior official said. He further noted this did not include costs to the provinces and territories, which would be even higher because they're responsible for more personal documents than the federal government is.

The Conservatives did not change the policy. Nor will the Liberals, said Mathieu Genest, a spokesman for Hussen.

"The birth-on-soil principle has been enshrined in our legislation since Canadian citizenship first came into existence in 1947. A change to this principle was planned by the Harper Conservatives, but abandoned after listening to the advice of experts," Genest said. But the Immigration Department still wants a better understanding of what's going on.

Griffith said he was inspired to delve into the question of how prevalent birth tourism is in Canada after he noted the number of non-resident births reported for Richmond Hospital in B.C. were disproportionate to the rest of the country, as calculated by Statistics Canada.

The data he collected from CIHI captured the number of mothers who paid out-of-pocket for their hospital bills, which was at least five times higher. He acknowledged this would include Canadian expatriates and foreign students whose hospital expenses were not covered by Canadian medicare.

Ontario immigration lawyer Gordon Scott Campbell said he's had several clients in recent years who have given birth while in Canada while in the middle of legitimate refugee or immigration processes.

For example, he said some women with visitor status live with their spouses while applying for spousal sponsorship, and some refugees arrive pregnant or become pregnant while waiting for their claims to be processed.

"It would seem extremely punitive, even misogynistic, arguably, to say that no woman should be able to become pregnant or be pregnant if you're not a permanent resident or a citizen of Canada," Campbell said.

"Are we talking about three people a year, four people a year, flying into Canada (to give birth)?" he asked. "I'm not sure we even have any proof of that. There might be anecdotal proof out there in media articles, but if we're talking two or three people a year, it's hardly a national crisis justifying legislation."

Vancouver Coastal Health, the authority that oversees the Richmond Hospital, said Thursday that taxpayers don't pay for non-resident births. The agency provided its own statistics, which differed slightly from Griffith's findings but which were also out of keeping with the numbers of non-resident births in Canada reported by Statistics Canada.

Statistics Canada says it generates its data from demographic information provided by vital-statistics registries in the provinces and territories. Parents complete these registry forms and are responsible for filing them with local registrars, the agency said. Griffith believes Statistics Canada might record lower numbers of non-resident births because parents put local addresses on these forms that aren't their real permanent addresses.

As part of his response to Parliament, Hussen said Canada does not collect information on whether a woman is pregnant when entering Canada, nor can a woman legally be denied entry solely because she is pregnant or might give birth in Canada.

With files from Laura Kane in Vancouver.