The jokes were rampant many weeks ago, when the pandemic was new and the nation was ordered to stay home in mid-March to prevent the spread of the coronavirus.

Commentators smirked that the United States should expect a baby boom in nine months as couples began to shelter in place with few opportunities for recreation outside of the bedroom.

Now comes a report from the Brookings Institution, the public policy think tank, that puts the lie to those nudge-nudge, wink-winks.

“Tremendous economic loss, uncertainty, and insecurity” brought on by COVID-19 likely will cause a decrease of 300,000 to 500,000 births, according to the Brookings report.

A decline that steep would represent a 13% drop.

The researchers based their forecast on data extrapolated from the Spanish flu pandemic of 1918 and the Great Recession of 2007 to 2009.

Couples often decide to have children based on economic conditions, said Brookings economists Melissa S. Kearney and Phillip Levine. Prior research found that an increase of 1 percentage point in the unemployment rate is linked with a drop of 1.4% in the birth rate.

The unemployment rate now hovers about 13%, and the Federal Reserve expects it will still be at 9.3% by the end of the year.

On top of the economic impact, libido-destroying anxiety and social distancing brought on by the pandemic also will contribute to the decline in births, wrote Kearney and Levine. “Our analysis of the Spanish Flu indicated a 15% decline in annual births in a pandemic that was not accompanied by a major recession. And this occurred during a period in which no modern contraception existed to easily regulate fertility.”

The decline comes on top of decades of plummeting fertility rates, which last year hit their lowest point in 35 years. According to a U.S. Centers for Disease Control and Prevention report released in May, fertility rates in the U.S. dipped to “below replacement levels” in 2019.

“The circumstances in which we now find ourselves are likely to be long-lasting and will lead to a permanent loss of income for many people. We expect that many of these births will not just be delayed — but will never happen,” wrote Kearney and Levine. “There will be a COVID-19 baby bust. That will be yet another cost of this terrible episode.”

A baby bust could have a continuing impact on the economy after the threat of the pandemic has passed, said Mauro Guillén, a professor at the Wharton School of the University of Pennsylvania.

“If you were already assuming that Social Security would be underfunded in several years, this will bring that forward so that it will happen a little bit earlier,” said Guillén, who has written extensively about the impact of demographic trends on industry. “The other more immediate and obvious effect will be on the parts of the economy which cater to the baby population.”

Guillén said there are several other factors, unmentioned in the Brookings report, that may postpone or slow the number of births.

During the COVID-19 peak, all elective health-care procedures were suspended, including fertility treatments. About 78,000 children are born each year with the help of assisted reproductive technologies, according to the CDC. “Even when the clinics reopen, couples may not want to spend the money right now because they’re hoarding cash,” Guillén said.

Unwanted pregnancies also will likely fall, he said. According to the National Institutes of Health, there are three million unplanned pregnancies in the U.S. each year. “They happen mostly with teenagers,” Guillén said. “Now they’re not in school, there are fewer opportunities to meet up. So that rate could be coming down, too.”