Provisional 2016 data showed a 1% decline from the year prior. That brings the general fertility rate among women 15 to 44 to 62.0 births per 1,000 women.
Experts in demographic trends fear the falling rate could signal the beginning of larger economic woes for the US.
In many industrialized countries around the world, the male-dominated labor force is shifting to become more egalitarian. As more members of both sexes choose to prioritize their careers over their personal lives, family planning is taking a backseat.
In the most extreme cases, such as in the so-called "demographic time bomb" that has formed in Japan, populations have actually started declining. Economists have forecasted this demographic time bomb - a way of referring to the vicious cycle of low fertility and economic downturn - could spread in 20 years' time to other countries that have similar demographics as Japan in the late 1990s.
They call it the "Japanization" of the global economy.
US population growth has followed a similar, albeit less extreme, trajectory. Millennials are increasingly choosing to forgo parenting in an effort to move up in their careers, pay off their massive student debt, and gain financial independence from their parents.
The US case is notable, however, when it comes to its lack of federal parental leave policies. There are only three other countries on Earth that do not offer employees paid time off on a national level. Research has found this factors into low fertility because poor work-life balance forces couples to choose between having kids or pursuing careers. They can't do both.
For that reason, demographers often encourage world leaders to enact more family-friendly policies if they want to boost fertility rates.
"The countries that have been most successful at adjusting for a dual role for women, both as mothers and as professionals or at least workers, interestingly end up with more of both," Richard Jackson, president of the nonprofit research group Global Aging Institute, told Business Insider in 2016. " They end up with higher fertility rates and more working women."