TORONTO -- A shows the typical Canadian family is diverging further from the nuclear structure that was once the norm, with more couples living in common-law partnerships and without children.

Statistics Canada released results Wednesday from the 2021 national census that show 23 per cent of couples who live together are unmarried -- the highest percentage of any G7 nation.

"Since Statistics Canada first began tracking common law couples 40 years ago, in 1981, there's been enormous growth, both in the number and the proportion of couples that are living common law," said Nora Galbraith, a senior analyst with Statistics Canada's centre for demography.

"The number has actually multiplied over five times in the last 40 years. In comparison, when we look at married couples, the growth has been much more modest."

Over the same period, the number of married couples grew by just a quarter.

The trend, Galbraith said, could be attributed to a number of things.

"It's reflecting different societal changes, potentially more secularization within the culture in Canada," she said.

In many instances, common-law partners are opting for that sort of union after being in a previous relationship, Galbraith added.

"When we look at stepfamilies, the share that are common law is much higher than among couples without children," she said.

Statistics Canada said the prevalence of common-law partnerships is due in part to the union's popularity in Quebec, where 43 per cent of Canada's common-law couples live.

Omitting Quebec, the agency said the share of common-law couples in Canada would have been 17 per cent in 2021.

Meanwhile, the data reveals the percentage of couples with a child at home is on the decline.

On census day in 2021, 50 per cent of couples who lived together had children, compared to 51.1 per cent in 2016. In 1981, the proportion was 64 per cent.

Statistics Canada said that's because of the "combined trends of population aging and decreasing fertility."

"As the average age within the population keeps shifting a bit older, that means that people that are in couples are older on average, so they're less likely to be at that stage of life where they have younger dependent children living at home with them," Galbraith said.

But at the same time, people are less likely to have children. In 2020, the most recent year for which Statistics Canada has data, there was an average of 1.4 children per woman, Galbraith said -- a record low.

"At the same time, the average age of child-bearing has steadily increased over time," she said. "With these shifts, the result is that fewer young adults that are in a couple have children at home today."

The census data show the share of single-parent households has stayed relatively steady, but the percentage of children living predominantly with their fathers has risen.

The share in 2021 was 21 per cent, compared to 14 per cent in 1981.

And for the first time, the snapshot of Canadian families also includes more detailed information on gender diversity within families after Statistics Canada amended the census in 2021 to differentiate between sex assigned at birth and gender.

The data show that one in 250 couples includes at least one person who is transgender or non-binary.

Margo Hilbrecht, executive director of the Vanier Institute of the Family, said census releases like this are key to ensuring government policy keeps up with social change.

"This is the first step in motivating policymakers to reassess what they've been doing and consider where other changes need to be made," she said.

This report by The Canadian Press was first published July 13, 2022