A new working paper from the National Bureau of Economic Research claims to have found causal evidence that the iPhone has driven a significant share of America's falling birth rate. Overall, the diffusion of the iPhone explains 33–52% of the decline in the general fertility rate among women aged 15–44, according to economists Caitlin K. Myers of Middlebury College and Ezekiel Hooper.
The finding arrives as the U.S. continues to set unwanted records. The general fertility rate dropped to 53.1 births per 1,000 women ages 15 to 44 in 2025, down from 53.8 in 2024. The rate has been trending downward since 2007 and is down roughly 23% over that period.
The AT&T; Natural Experiment
The Myers-Hooper paper exploits an unusual circumstance: from June 2007 through February 2011, the iPhone was sold only on AT&T;, allowing the researchers to identify its effect from variation in AT&T;'s mobile broadband coverage. Areas with better AT&T; coverage got earlier and fuller access to the first modern smartphone. Those same areas saw earlier and sharper drops in births.
Entropy-balanced Poisson and synthetic difference-in-differences event studies imply that access to the iPhone reduced births by 4.5–8.0% at ages 15–19 and 3.2–6.6% at ages 20–24. The effects diminished but remained statistically significant among older women.
National-survey evidence on time use and sexual behavior is consistent with the iPhone reducing in-person interactions, increasing pornography use, and reducing sexual frequency.
A Global Pattern
The Myers-Hooper paper is not alone. A separate study from University of Cincinnati researchers Nathan Hudson and Hernan Moscoso Boedo examined birth rate patterns across 128 countries with different healthcare systems, religions, and economic conditions. In many of them, they detected the same kink in the curve, shifted in time depending on when smartphones became a mass-market product locally.
Their findings show that the number of births fell first and fastest in the areas that received high-speed mobile connectivity earliest. The mechanism appears to be social rather than biological. In 2003 U.S. teenagers still spent 68 minutes a day in person with friends and other social contacts; by 2019 that figure had fallen to just 38 minutes. Over the same period, the time they spent on screens for leisure activities rose from 22 to 96 minutes a day.
The teen fertility collapse is especially stark. The fertility rate for teenagers fell 7% in 2025 alone and has dropped more than 70% since 2007.
Important Caveats
Critics have raised methodological concerns. What sorts of areas were more likely to get connectivity early? Densely populated metropolitan areas, where residents are more likely to be culturally liberal, where young people with big professional ambitions are more likely to move. The places that got 4G later tend to be more rural and conservative, with different fertility norms to begin with.
The Hudson-Moscoso Boedo paper itself is explicit about scope. "Whatever the smartphone shock is doing to fertility, it is doing to teens," they write. "The entire 25+ population, which accounts for roughly 80 percent of women of reproductive age in these countries, exhibits no detrended response in the typical country." That matters. A collapse in teen pregnancy is, by many public health metrics, a desirable outcome. Whether that same mechanism explains the broader fertility decline among adults is less clear.
The Financial Times' John Burn-Murdoch, who has written extensively on these papers, argues that smartphones and social networks work as "accelerators, amplifiers and internationalizers" of social and cultural changes that have been developing for decades. He added that even if social media disappeared overnight, the trend probably wouldn't reverse immediately, because many of the cultural norms eroded by the internet had been built for centuries in social and economic contexts that no longer exist.
That framing is worth dwelling on. Fertility rates have been falling in rich countries since the 1970s, well before anyone had a phone in their pocket. The reasons for the declines from the 1970s to the early 2000s involve greater female autonomy and a mismatch between the desires of men and women, according to Nobel laureate Claudia Goldin. Smartphones may have accelerated something already underway.
What Happens Next
Women are increasingly delaying childbearing into their 30s. Nearly half of U.S. women around age 30 are now childless, up sharply from past decades. Census data shows the share of childless women ages 25 to 29 rose from about 50% in 2014 to 63% in 2024. Whether these delays translate to permanent childlessness or simply shifted timing remains the critical question.
An analysis by the Federal Institute for Population Research in Germany shows that women would like to have an average of 1.76 children, and men 1.74, suggesting the desire for children persists even as actual births fall. Among women, the so-called "fertility gap"—the difference between the desired and the actual number of children—has recently doubled to 0.41.
The smartphone thesis is provocative because it suggests a technological intervention, not an economic one, may be needed. The debate over technology's social costs is not new, but assigning a specific percentage of fertility decline to a specific device sharpens the stakes considerably.
The University of Cincinnati team is pursuing follow-up research. "In follow-up research we are investigating this shift from deeper relationships to broad and shallow ones facilitated by the digital revolution," said Moscoso Boedo.
For policymakers wrestling with aging populations, shrinking workforces, and strained pension systems, the question is whether any intervention—economic subsidies, parental leave, housing assistance—can counteract a shift in how young people spend their time and form relationships. The broader behavioral effects of ubiquitous digital technology remain poorly understood. If smartphones really do explain a third of the fertility decline, that ignorance may prove costly.
