This is one nasty city trend that Mayor Bill de Blasio can’t blame on a “perfect storm.”

New York City’s population shrank significantly even before the COVID-19 pandemic took a bite out of the Big Apple, city data reveals.

The city’s population declined 2.6 percent in 2018 — two years before the COVID outbreak, the Health Department’s 2018 Vital Statistics report on health outcomes said.

The report indicated the city’s population dropped from 8,622,698 in 2017 to 8,398,748 in 2018. That’s 223,950 fewer residents.

The figure, if accurate, would represent the biggest one-year population drop since the 1970s.

De Blasio over the past year has taken to blaming a sharp rise in shootings and murders and drop in quality of life on the “global pandemic,” repeatedly calling it a “perfect storm of negative factors.” But this sharp decline predates the city’s COVID-19 shutdown which began in March 2020.

De Blasio over the past year has taken to blaming a sharp rise in shootings and murders and drop in quality of life on the “global pandemic,” repeatedly blaming it all on a “perfect storm of negative factors.” But this sharp decline predates the city’s COVID-19 shutdown, which began in March 2020.

The study revealed a continuing trend of a declining birthrate in the city: There were 114,296 births in 2018, a slight drop from 117,013 in 2017.

And the number of people tying the knot also dropped. The number of couples getting married fell from 82,866 in 2017 to 76,688 in 2018.

Staten Island Councilman Joe Borelli blamed the city’s sky-high cost of living and decline in quality of life as pushing residents to head for the exits well before anyone had even heard of COVID-19.

“It’s all quality of life and cost of living. So many of my friends I grew up with have gone across the bridge to New Jersey, Pennsylvania and other points south,” Borelli said.

He said one frustrated friend who had a real estate business moved to Texas.

“The population loss was only slightly noticeable in 2018. Now we see a tidal wave of people leaving,” the Republican councilman said.

One population expert said the biggest reason for Gotham’s population decline was a drop in foreign immigration, which generally offsets the people fleeing the city.

“Foreign immigration has slowed down a lot under President Trump,” said EJ McMahon of the Empire Center for Public Policy.

He said in previous years, foreign immigration and births offset Big Apple residents who moved to other states, such as New Jersey and Florida.

Previous census data revealed that New York state recorded the nation’s biggest population decline from mid-2019 to mid-2020 — a development that would likely cost the Empire State at least one congressional seat.

The Health Department referred to City Planning Department documents when asked about the population loss.   

“While the city’s population has shown an overall increase since 2010, these estimates also reveal a pattern of population losses in each of the last three years,” the Planning Department said in an analysis of the city’s population through July 2019.

The analysis said international immigration to the city plummeted by 46 percent since 2016 because of more restrictive federal immigration policies. The drop mirrors the national decline in foreign immigration, planning officials said.

By comparison, the analysis said domestic outflow of city residents — those moving to other states —  had not changed much.

The planners also cited the city’s lower birth rates and more deaths from an aging population.

“The recent declines in the city’s population are a result of changes in federal immigration policy that have resulted in fewer immigrants (and also lowered births), and an aging population that has increased the number of deaths,” the planning officials said.