2021 saw a mini “baby bump” among U.S.-born mothers, according to a new working paper from the National Bureau of Economic Research (NBER). While the fertility rate declined in 2020, a small baby boom helped it bounce back beyond pre-pandemic trends by 6.2%. The mini boom resulted in a net increase of 46,000 births, the study found.

It’s the first major reversal in U.S. fertility rates since the Great Recession, the NBER researchers wrote: “large enough to reverse two years of declining fertility rates.” The total number of children a woman was projected to have during her lifetime dropped from 2.1 to 1.6 from 2007 to 2020, and birth rates hit a record low during the pandemic. It’s all prompted some demographers and Musk to fear a demographic crisis (other experts have said the declines are nothing to worry about if our economy adapts accordingly). But the NBER researchers attribute the drop in fertility rates in 2020 to fewer births among foreign-born mothers, who couldn’t travel to the U.S. during lockdown. 

The researchers looked at births in the nation from 2015 to 2021 and in California from 2015 to August 2022, noting that the California data tracks “closely” with overall U.S. data. They found that this “bump” was most evident among first-time mothers and women under 25, leading them to believe that the pandemic sped up family planning. Indeed, spending more time at home created boredom or baby fever for some Americans; a 2020 Fortune poll found that 34% of respondents were planning to start a family earlier than expected due to the pandemic.

The bump was more pronounced for women aged 30 to 34 as well as college-educated women aged 25 to 44, the study found. The researchers suggest that the ability to maintain job security and work remotely made it easier for these demographics to have children. Recessions typically go hand in hand with declines in birth, as people tend to wait to have kids during times of economic difficulty. But the coronavirus recession ended up being different because of extra unemployment assistance from the government, the rise of remote work, and less access to abortion or reproductive care, the researchers wrote.

U.S. fertility rates have been declining for decades, falling in line with worldwide trends. It’s partly the result of economic progress, as more women push back having children to prioritize their career or decide not to have them at all. An analysis from Professor Myers for the New York Times found that birth rates were declining more in places with more career opportunities. 

But children are also expensive, especially in this economy. Even though federal assistance helped households save more, inflation has bumped the cost of having one child to around $300,000. The childcare crisis has only made raising a kid even more pricey. Finances often deter individuals from having kids, the Pew Research Center finds.

As Americans dip into their savings, who knows how long the nation’s baby bump will last?