The year the iPhone launched, 2007, the United States was recording roughly 4.3 million births annually and had maintained broadly stable fertility for nearly three decades. By 2025, the fertility rate had fallen to the lowest level on record, with about 3.6 million babies born, translating to approximately 53 births for every 1,000 women of reproductive age. Economists, demographers, and public health officials have spent years cataloguing explanations: the 2008 financial crisis, the rising cost of childcare, the expansion of contraception access, shifting cultural attitudes toward parenthood. Each explanation accounts for something. None has fully accounted for the timing, the speed, or the geographic consistency of the collapse.
A new working paper published in June 2026 by the National Bureau of Economic Research puts a specific and provocative hypothesis on the table. Authored by Caitlin K. Myers and Ezekiel Hooper, the paper is titled “Is the iPhone Birth Control? Causal Evidence from AT&T’s 2007-2011 Carrier Monopoly.” The argument it makes is neither casual nor easily dismissed: that the arrival of the smartphone did not merely coincide with falling birth rates, it caused them.
The claim has already drawn significant attention from researchers who accept its methodology and from skeptics who question whether any single device can bear that much causal weight. The paper is worth examining carefully not for its headline, but for the specific causal story the researchers identify and the natural experiment they construct to test it.
The AT&T Experiment: How Researchers Isolated Smartphone Access
Most research on technology and social behavior runs into the same problem: the people who use a given technology most heavily tend to differ from non-users in other ways that could independently explain the outcomes being studied. Controlling for those differences is difficult. Myers and Hooper found a way around that problem.
From June 2007 to February 2011, AT&T was the only carrier distributing the iPhone, as documented in the NBER working paper, which pioneered smartphone technology – meaning the researchers were able to create a natural experiment by looking at areas where AT&T was selling the device and comparing them to parts of the country where the phone was not yet accessible. This carrier exclusivity was a commercial decision made by Apple and AT&T, not a deliberate research design, but it functions as one. Counties where AT&T’s mobile broadband network was dominant received the iPhone first. Counties dominated by Verizon and Sprint did not.
Comparing birth rates across counties and controlling for confounding factors, the authors concluded that access to the iPhone reduced births, particularly among younger women. In the first four years of the iPhone’s release, geographies with access to the device saw reduced births from 4.5% to 8% for ages 15 to 19, and a 3.2% to 6.6% reduction in births for ages 20 to 24. These birth rates decreased the most among teenagers, but were reduced in every age group.
Compared to counties with dominant Verizon and Sprint coverage, which only began to receive Android devices in 2009, there was no effect on fertility related to the iPhone release. Pay attention to what that tells you. If something else about AT&T coverage areas – their demographics, their economies, their geography – was driving birth rate declines, you would expect those declines to persist independent of when smartphones arrived. The fact that non-AT&T counties showed no parallel decline during the same period significantly strengthens the case that the device itself was the operative variable.
The Reason: Relationships, Not Reproductive Choice
The paper’s argument is not that the smartphone replaced contraception or that it changed anyone’s conscious decision about whether to have children. The cause runs deeper than that.
The paper found that the advent of the iPhone and other smartphones reduced relationship formation and partnered intimacy. Smartphones changed the way people – especially young adults – spend their time. They’re increasingly likely to be alone, or to have interactions with friends happen online rather than in person. Less time together, in physical proximity, translates directly into fewer pregnancies, both planned and unplanned.
Drops in unintended births to young people are a key factor in the broader decline in US births and smartphone use patterns, the researchers say. In some ways, the smartphone interrupted the spontaneous social encounters that can lead to an unintended pregnancy. The smartphone may have become a substitute for physical contact and in-person human interaction, Hooper said.
Myers summarized the core finding in an email to The Register: “It’s pretty much undeniable that births fell faster in places with AT&T coverage,” she said. “As a scientist, I’m loath to ever say causality is ‘proven’… but I would say that we’ve identified a compelling natural experiment and that it strongly points to a large and causal relationship between iPhones and fertility.”
The paper also does not claim that every birth prevented was an unintended one. Relationship formation – meeting people, dating, building partnerships – is the upstream condition for both planned and unplanned pregnancies. Disrupt relationship formation broadly enough and the downstream effects on births follow regardless of how individuals feel about parenthood in the abstract.
The Broader Decline: A Two-Decade Trend in Context
To understand what the Myers-Hooper paper is actually claiming, it helps to have the full scope of the fertility decline in view. The United States fertility rate has now been in decline for two decades, dropping nearly 23 percent since 2007. A 2% drop in 2023 put US births at fewer than 3.6 million, the lowest one-year tally since 1979. US births fell again in 2025. Slightly over 3.6 million births were reported through birth certificates, about 24,000 fewer than in 2024, appearing to confirm predictions by experts who doubted that a slight increase in births in 2024 marked the start of an upward trend.
The paper is careful about what it is and is not claiming. The study noted that smartphones were not the sole cause of declining fertility, but they could account for nearly half of the drop. That is a significant claim – not that the iPhone explains everything, but that it explains approximately half of one of the most consequential demographic shifts in modern American history.
Wellesley College economics professor Phillip Levine told Reuters that factors such as “greater and more demanding job market opportunities, expanded leisure options, and increased intensity of parenting” have made “the option to have children less desirable.” These explanations and the smartphone hypothesis are not mutually exclusive. Several forces can operate simultaneously, and the paper makes no claim to having found the only cause – only a large and previously underweighted one.
A Global Pattern That Predates Policy Differences
One of the more striking pieces of evidence supporting the smartphone hypothesis is that fertility declines are not confined to the United States, and they track smartphone adoption across very different policy environments.
Fertility rates have plummeted across diverse countries, from wealthy nations like the US and UK to developing economies in Latin America, Africa, and the Middle East, in a remarkably synchronized pattern. Across these countries, the demographic decline accelerated sharply in recent years, with many seeing fertility drop 20 to 40 percent below previous trends exactly when smartphones and high-speed mobile internet became widespread. In the US and UK, the downturn aligned with the iPhone era around 2007. In Mexico, it followed around 2012. Similar patterns emerged in other nations as mobile adoption surged, regardless of prior economic conditions, cultural norms, or government policies.
In a separate but related working paper from April 2026, economists Nathan Hudson and Hernan Moscoso Boedo at the University of Cincinnati examined smartphone adoption and teen fertility across 128 countries and found that teenage fertility rates fell sharply once smartphones became mainstream, regardless of differences in healthcare systems, religion, or economic conditions. As smartphones “changed how teens spend time with each other,” the researchers wrote, teen fertility rates dropped further around the globe. The Financial Times put the study front and center in its own investigation into the global birth rate collapse, published in May 2026.
The cross-cultural consistency cuts against explanations rooted in country-specific policy choices. The United States, Mexico, and several African nations do not share healthcare systems, contraception access rates, or social welfare programs. They do share the moment at which smartphones went from rare to ubiquitous.
The same trend carried a darker parallel statistic. “The same instrument that produces a collapse in teen fertility produces a surge in teen suicides,” the University of Cincinnati study noted. That coincidence has been observed independently in mental health research and lends further weight to the idea that mass smartphone adoption changed the social lives of young people in ways that extended well beyond how they communicated.
The Socializing Collapse
The data on in-person interaction among young Americans over the smartphone era is striking on its own terms. In 2003, US 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, according to the American Time Use Survey. In-person socialization rates among young adults dropped by nearly 50% between 2010 and 2019, and that was before COVID-19 lockdowns made it even worse.
The same period saw steep declines in dating, sex, and marriage. Marriage rates dropped from 9.8 marriages per 1,000 people in 1990, to 6.5 in 2018, to 6.1 per 1,000 in 2023. Rates of sexual activity fell alongside. In 1990, 55% of adults ages 18 to 64 reported having sex weekly, but by 2024 that number had fallen to just 37%.
None of these trends proves causation by themselves. But they are consistent with the story the Myers-Hooper paper tells: a device that redirects attention inward, toward individual screens, makes the physical proximity that leads to relationships, sex, and children less likely to happen. The primary culprit, according to the analysis and supporting research, is a dramatic shift away from in-person socializing. Smartphones and social media have lowered the cost of shallow digital connections while making real-world interactions – essential for forming relationships – harder to initiate and sustain.
Declining social connection and loneliness have been documented extensively across age groups that came of age during peak smartphone adoption, and the Myers-Hooper paper situates the fertility data within that broader pattern of social withdrawal.
The Critics: What the Paper Doesn’t Prove
The paper has generated real skepticism, and the critics are worth taking seriously. Other experts remain skeptical, noting that fertility has declined for decades and pointing to factors like expanded contraception access.
The researchers themselves acknowledge they can’t completely rule out the possibility that areas with AT&T coverage differed in other ways that would make birth rates fall faster. That is the inherent limitation of any natural experiment: you can identify a plausible instrument and control for observable differences, but you cannot guarantee that the instrument is truly exogenous – that AT&T coverage areas were, in every relevant dimension, identical to non-AT&T areas before the iPhone arrived.
Critics at Reason magazine have pointed to a notable gap in the findings: there was “no effect” for Black women of any age. If the iPhone were acting as a uniform suppressor of fertility across the population, you would expect to see consistent effects across demographic groups. The absence of an effect for one large demographic group raises questions about whether the causal story the paper proposes is operating the way the researchers claim.
The study’s formal status is also relevant. NBER working papers are circulated for discussion purposes; they have not yet been through peer review. The findings are preliminary and should be treated as such. What the paper offers is a compelling natural experiment that identifies a strong statistical association and a plausible causal explanation – not a settled scientific consensus.
Policy Responses and Their Limits
The fertility decline has attracted growing political attention, with several governments attempting to reverse it through financial incentives. A pronatalist movement has gained momentum under the Trump administration, buoyed by policy moves geared toward encouraging people to have more children.
The authors of the NBER paper said financial incentives for having children – such as those proposed by the Trump administration – would have only modest effects on boosting birth rates, and that such incentives would come at a “steep cost.” That conclusion aligns with the international evidence. Countries that have tried cash transfers, parental leave expansions, and IVF subsidies have seen, at best, modest and temporary upticks. No high-income country has yet reversed its fertility decline through policy alone.
If the smartphone is genuinely responsible for a substantial portion of the decline, that would reframe the problem in a way that financial policy cannot easily address. The nation’s birth rate is also a key factor in determining the financial health of Social Security’s trust fund. The fewer younger Americans there are, the fewer workers exist to pay into the system that supports more than 70 million retirees and others. Social Security’s trustees have forecast that it would take until 2050 for the total fertility rate to hit 1.9 children per woman, a decade longer than their prior estimate, reflecting expectations that the rate “will recover relatively slowly from current low levels.”
America’s fertility rate hit a new record low of 1.57 in 2025, well below replacement rate. The replacement level is approximately 2.1 children per woman, the number needed to keep a population stable without immigration. The gap between 1.57 and 2.1 is not a rounding error. It is the difference between a stable population and one that will shrink measurably in the coming decades.
Read More: 10 Things Parents Say That Accidentally Crush Their Child’s Confidence
What the Data Actually Demands
The Myers-Hooper paper is not a reason to panic about smartphones, and it is not a reason to dismiss the fertility decline as a technology problem with a technology solution. What it does is shift the frame of the conversation in a way that is both more uncomfortable and more honest than the policy debates currently dominating the discussion.
Financial incentives – the baby bonuses, expanded IVF access, and parental leave proposals that governments from Washington to Budapest have rolled out – assume that people want to have children but face material obstacles. The smartphone hypothesis points at something upstream of that: people are spending less time in the kinds of physical proximity and sustained social contact that lead to relationships, partnerships, and the decision to have children in the first place. A tax credit does not fix a generation that is, as the data on socializing shows, meeting less, dating less, and having sex less than any prior cohort for which records exist.
The clearest takeaway from the combined body of evidence is also the simplest: the conditions that lead to relationship formation, partnered intimacy, and childbearing require physical presence and unmediated time. That does not mean smartphones need to be banned or that screens are the only variable worth watching. It means that policymakers and individuals alike are going to have to reckon with the fact that the same device most people carry everywhere has reorganized the social lives of young adults in ways that are now visible in birth registration data. The fertility decline that began in 2007 is now nearly two decades old. At some point, the timing stops being a coincidence. As Myers puts it: “People just aren’t forming the relationships that result in children.” That is a different kind of problem from the ones that tax credits and IVF mandates are designed to solve, and it will likely require different kinds of answers.
AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.