The findings are not surprising to many demographers, who have noted similar declines after catastrophic events such as the 2008 financial crisis and the 1918 influenza pandemic. But they are still noteworthy.

“We definitely expected there to be a drop in birth rates as a result of the [COVID] pandemic because of the history of disasters in general,” says Philip Cohen, a sociology professor at the University of Maryland, who was not involved in the study. “How it would play out was unclear, so it’s really interesting and important that we’re getting these results now.”

Cohen’s own research, described in a recent preprint study that has not yet been peer-reviewed, has shown that Florida and Ohio experienced birth-rate declines during the pandemic. He found steeper drop-offs in counties that experienced greater numbers of COVID cases and lower levels of mobility. Cohen notes that the PNAS study includes U.S. data through December 2020 and that more recent numbers show a larger decline.