The answer to what’s driving the steep decline in fertility in the U.S. that began in 2007 has eluded researchers for some time. Now, a new study suggests that the advent of smartphones is at least partially responsible, as some social scientists have long suspected.

The study, released in June, used mobile coverage maps cross-referenced with fertility data to conclude that the release of the iPhone, the first modern smartphone, is associated with an accelerated decline in fertility that has continued to the present day.  

In 2025, 710,000 fewer babies were born in the U.S. than in 2007, the year the first iPhone went on sale. The use of iPhones, specifically, may account for between 33% and 52% of the drop in in births among women aged 15 to 44 in the four years since the product’s initial release, the authors of the study argue.

In terms of the reasons why a society with smartphones might produce fewer babies than a society without them, the researchers theorize that the opportunity for more screen-mediated rather than in-person interaction has likely led to fewer people forming in-person relationships, thus leading to fewer pregnancies. The researchers also note that smartphones provide easier access to pornography — which may be used as a substitute for sex — as well as access to information about contraception and abortion. 

For many Catholic social scientists and those who work with families and young people, these speculative reasons ring true — they reinforce the insight, widely shared among Catholics, that the rise of smartphone culture has had a negative effect on most kinds of in-person socialization, in many cases exacerbating loneliness and isolation and serving as a barrier to fruitful, holy relationships.  

The Findings

In the June paper from the National Bureau of Economic Research (NBER), which has not yet been peer-reviewed, researchers Caitlin Myers and Ezekiel Hooper explain that they used the rollout of the iPhone beginning in June 2007, which was originally available exclusively on the AT&T network, as a natural experiment. 

They examined the fertility rates in U.S. counties with near-universal AT&T coverage and compared them to counties with little or none. They found that although birthrates declined everywhere during the period studied, they dropped the most in counties with extensive AT&T coverage, even controlling for the fact that many of those counties were relatively urban and affluent, as well as several other factors. 

Based on their analysis, the researchers conclude that access to the iPhone reduced births during the years 2007-2011 by 4.5% to 8.0% among ages 15 to 19 and 3.2%-6.6% among ages 20 to 24, with statistically significant but smaller declines among older cohorts. 

‘A Prime Cause’

A few social scientists have praised the researchers’ methods and cautiously defended the study’s credibility. But the merits and conclusions of the study are still being hotly debated online, with users pointing out that a starting point of 2007 means that the drop in fertility also corresponded to the economic pressures of the Great Recession, as well as the ever-increasing availability of the abortion pill and other forms of contraception. 

Patrick Brown, a fellow at the Ethics and Public Policy Center who studies family and demographic trends, told the Register that while there is certainly no single cause behind the decline in fertility, the new studies point to “suggestive evidence of a key mechanism.” 

“It’s clear that increasing availability of digital tech has been a prime cause for declining relationship formation,” Brown said in an email. 

According to Mark Regnerus, a sociologist and president of the Austin Institute for the Study of Family and Culture, Catholics can already recognize that ubiquitous smartphone use makes in-person relationships, including friendships and marriage, feel less necessary and acts as a “contraceptive” of sorts. 

As Catholics, “we would do well to more actively expand and privilege device-less time between friends and between husbands and wives,” Regnerus said in written comments to the Register.

Crystal Collier, a therapist and educator who advises the Catholic-led organization Smart Families, told the Register that the new studies serve as further proof of what neuroscience research has shown for years: Excessive technology use and access to pornography are reshaping how young people develop intimacy, relational and resiliency skills. 

For parents, these studies reinforce the importance of restricting access to certain media and prioritizing in-person opportunities and exposure to real-life skills to avoid wiring young brains for “convenience and avoidance rather than perseverance,” she continued.

The Fertility Crisis Is a Marriage Crisis

Much of the well-documented decline in fertility in the U.S. in recent decades has been the result of fewer births among those who are unmarried — including teenagers — meaning children who are born today are more likely than in previous decades to be born to parents who are married. While Brown has described this fact as a “silver lining” to the fertility crisis, the steep decline of marriages in recent decades, including Catholic marriages, remains a serious concern for society at large and for the Church, as the Register has previously reported. 

According to a recent Heritage Foundation report, Americans in 2025 were nearly half as likely to be married by age 30 to 35 than in 1962. Among Catholics, the number of marriages recorded has dropped by nearly 75% since 1970, despite an increase in the Catholic population overall.

While digital spaces like social media and dating apps can facilitate encounters that lead to real friendships and even marriages, social media and smartphone culture has long been recognized as a major factor in the dating crisis seen among young people today, whereby one in three adults currently in their 20s — if trends continue — may never marry. 

‘Cherish Physical Presence’

Rachael Tvrdy, director of the Office of Family Life and Discipleship for the Diocese of Lincoln, Nebraska, said she has seen in her work with young adults, engaged couples and married couples that excessive amounts of screen-mediated socialization — without the appropriate balance of in-person interaction — tends to weaken men and women’s sense of responsibility toward “those who are providentially placed right in front of us.” 

She said she often sees in disconnected marriages a tendency to escape into online activity to avoid discomfort, conflict or lack of intimacy at home. This behavior can turn into perpetual avoidance, leading to pornography use, online addictions — such as gambling, gaming and shopping — and endless scrolling to dissociate from painful reality, she continued. 

“It provides a temporary dopamine hit that drives people to avoid the real pressures of family life, but over time it can become a constant supply of escape that replaces authentic intimacy,” Tvrdy said in an email. 

In Pope Leo XIV’s recent encyclical Magnifica Humanitas, the Pope writes that technology is “never neutral,” but rather shapes and is shaped by those who use it. Leo extended an invitation to Catholics to “cherish places and times where physical presence remains crucial, such as shared meals, Christian community gatherings, time spent with the lonely and serving the poor.”

Brown agreed: “[Pope Leo’s] recognition should inspire us to push for more limits on kids and tech, to recognize the hollowness of dating apps and short-form video apps, the need for greater legal barriers to access explicit content, and more.”