この研究はiPhoneがなければ出生率は低下しなかったと主張しているのか

研究は「iPhoneの普及が出生率低下に大きな因果関係を持つ」と示唆しているが、経済的不安や住宅費など他の要因も同時に作用していると認めている。iPhoneへのアクセスが出生率低下の最大52％を説明する可能性があると試算したが、残りの部分は他の要因に起因すると見ている。

なぜAndroid端末ではなくiPhoneに焦点が当てられているのか

2007年から2011年までiPhoneはAT&Tのみで販売され、地域によってアクセス可否が明確に分かれたことが「自然実験」として理想的だったため。Android端末は複数のキャリアで同時に普及したため、同様のクリーンな比較が難しかった。

この研究結果は日本にも当てはまるのか

研究は米国のデータに基づいており、日本に直接適用できるかは不明。ただし、スマートフォンの普及と出生率低下の関係は、文化的・経済的背景が異なる国でも類似のパターンが存在する可能性があり、今後の国際比較研究が待たれる。TITLE: iPhone Adoption Linked to U.S. Birth Rate Decline, NBER Study Suggests EXCERPT: An NBER working paper reports a "large and causal relationship" between iPhone adoption and declining U.S. birth rates. Analyzing data from the AT&T exclusivity era, it found notable declines among younger women. TAGS: iPhone, birth rate, economics, technology and society, mobile BODY: U.S. birth rates have been declining for nearly two decades, but economists have identified a new factor: the spread of the iPhone. According to a working paper from the National Bureau of Economic Research (NBER), comparing AT&T's mobile broadband coverage with county-level birth data from the 2007 iPhone launch until AT&T lost its exclusive sales rights in 2011 suggests a significant causal link between iPhone access and lower birth rates. The paper, authored by Caitlin Myers, an economics professor at Middlebury College and NBER research associate, and graduate student Ezekiel Hooper, concludes that counties with access to the iPhone via AT&T experienced a sharper decline in births compared to those without. "It's nearly impossible to deny that birth rates fell faster in areas with AT&T coverage," Myers told The Register. ## Research Methods and Results The researchers statistically controlled for confounding factors such as income, race, and education, and compared areas dominated by Verizon or Sprint (where the iPhone was effectively unavailable until Android devices became widespread) as a control group. They observed birth rate declines of up to 8% among women aged 15-19 and up to 6.6% among those aged 20-24. Statistically significant but smaller declines were also seen in older age groups. "Taken together, these cohort effects suggest that iPhone adoption deepened birth declines among women under 30 while simultaneously suppressing birth increases among older women," the paper explains. It further estimates that up to 52% of the overall decline in U.S. birth rates during that period could be attributable to iPhone adoption. ## Comparison with Control Group After Android devices began to spread widely in 2009, signs of declining birth rates also emerged in control areas, but the authors note that small sample sizes and limited data make conclusions less precise. "As a scientist, I hesitate to say it's 'proven,'" Myers said. "But I think we've identified a compelling natural experiment, and it strongly suggests a large and causal relationship between the iPhone and birth rates." ## Background and Industry Reactions U.S. birth rates have been consistently declining since 2007, with factors such as economic uncertainty, rising housing costs, and shifting career priorities cited. This study is notable for statistically demonstrating that the immersive experience of mobile devices may have reduced face-to-face interactions and opportunities for young people to meet, thereby affecting birth rates. In a LinkedIn post, Hooper noted that people he discussed the paper with were not at all surprised. "Counties with iPhone access were adjacent to those without. Teen and young adult birth rates fell faster in places where iPhones were available," he explained. ## Editorial Perspective ## Short-Term Impact The significance of this research lies in its quantitative capture of the social changes triggered by smartphone adoption. Over the next three to six months, similar analyses are likely to be attempted in other countries. It will also merge with ongoing research on the link between social media and mental health, further heating up the debate on tech companies' social responsibility. Apple has already moved to strengthen screen time management features, but such findings are bound to draw policymakers' attention. ## Long-Term Outlook Over a one- to three-year span, the relationship between smartphone dependence and demographics is expected to become a serious topic in public health and labor policy discussions. Declining birth rates are a common challenge for developed nations, and as an unintended consequence of technology diffusion, tech companies are being called upon to consider social impacts from the product design stage. Furthermore, this research method could serve as a model for evaluating the influence of AI assistants and social media on human relationships. ## Questions from the Editorial Team To what extent should companies be responsible for the impact of smartphones and social platforms on human reproductive behavior and family formation? While this study claims "causation, not just correlation," it also has the inherent limitations of observational research. Moreover, what metrics should we use to evaluate the trade-off between technological convenience and social costs? These issues go beyond economics, prompting a rethinking of the very relationship between technology and humanity. ## References - [If your sex life is dead, you can blame Steve Jobs - The Register](https://www.theregister.com/personal-tech/2026/06/09/study-links-iphone-rollout-to-decline-in-us-birth-rates/) — Published June 9, 2026 - NBER Working Paper (the relevant paper) FA

Does this study claim birth rates would not have declined without the iPhone?

The study suggests "the iPhone's spread has a large causal relationship with declining birth rates" but acknowledges that other factors such as economic uncertainty and housing costs are also at play. It estimates iPhone access may explain up to 52% of the decline, attributing the remainder to other causes.

Why focus on the iPhone rather than Android devices?

From 2007 to 2011, the iPhone was sold exclusively through AT&T, creating a clear natural experiment where access varied regionally. Android devices spread simultaneously across multiple carriers, making it harder to perform a similarly clean comparison.

Do these findings apply to Japan?

The study is based on U.S. data, and its direct applicability to Japan is unclear. However, a similar relationship between smartphone adoption and birth rate declines may exist in countries with different cultural and economic backgrounds, pending future international comparative research.

Gadgets

iPhone普及と米出生率低下に因果関係、NBER研究が示唆

NBERのワーキングペーパーが、iPhoneの普及と米国の出生率低下に「大規模かつ因果的な関係」があると報告。AT&T独占時代のデータを分析し、若年層での出生率低下が顕著だった。

June 10, 2026 1 min read Reviewed & edited by the SINGULISM Editorial Team

iPhone 出生率経済学テクノロジーと社会モバイル

iPhone普及と米出生率低下に因果関係、NBER研究が示唆 — Photo by William Hook on Unsplash

米国の出生率は過去20年近く低下傾向にあるが、経済学者らが新たな要因としてiPhoneの普及を特定した。全米経済研究所（NBER）のワーキングペーパーによれば、2007年のiPhone発売から2011年にAT&Tが独占販売を失うまでの期間、AT&Tのモバイルブロードバンドカバレッジと郡レベルの出生率データを比較した結果、iPhoneへのアクセスが出生率低下に有意な因果関係を持つことが示唆された。

ミドルベリー大学経済学教授でNBER研究員のCaitlin Myers氏と同大学院生のEzekiel Hooper氏が執筆した同論文は、AT&Tを通じてiPhoneを利用できた郡では、利用できなかった郡と比較して出生率が大きく低下したと結論づけている。The Registerの取材に対しMyers氏は「AT&Tのカバレッジがある地域では出生率がより速く低下したことはほぼ否定できない」と述べた。

研究手法と結果

研究者らは、所得、人種、教育水準などの交絡要因を統計的に制御した上で、VerizonまたはSprintが支配的なエリア（Android端末が普及するまでiPhoneが事実上使えなかった地域）を対照群として比較した。その結果、15〜19歳の女性では最大8％、20〜24歳では最大6.6％の出生率低下が観測された。年齢が高いグループでも統計的に有意ながらより小さな低下が見られたという。

論文は「これらのコホート効果を総合すると、iPhoneの普及は30歳未満の女性の出生減少を深め、同時に年長女性の出生増加を抑制した」と説明。さらに、同期間における米国の全般的な出生率低下の最大52％がiPhoneの普及に起因する可能性があると試算している。

対照群との比較

Android端末が広く普及し始めた2009年以降、対照群の地域でも出生率低下の兆候が現れ始めたが、サンプルサイズが小さくデータが限られているため、結論の精度は低いと著者らは指摘する。この点についてMyers氏は「科学者として因果関係が『証明された』と言うのはためらわれる。しかし、説得力のある自然実験を特定できたと考えており、iPhoneと出生率の間に大規模かつ因果的な関係が強く示唆される」と述べている。

背景と業界の反応

米国の出生率は2007年以降一貫して低下しており、経済的不安、住宅費の高騰、キャリア志向の変化など複合的な要因が指摘されてきた。今回の研究は、携帯端末の没入体験が若年層の対面交流や出会いの機会を減少させ、結果的に出生率に影響を与えた可能性を統計的に示した点で注目される。

Hooper氏はLinkedInへの投稿で、論文について話し合った人々が全く驚かなかったと述べ、「iPhoneが使える郡と使えない郡が隣接していた。10代や若年成人の出生率は、iPhoneが使える場所でより速く低下した」と説明している。

編集部の見解

短期的影響

本研究成果は、スマートフォンの普及が引き起こした社会的変化を定量的に捉えた点で重要だ。今後3〜6カ月の間に、同様の分析が他国でも試みられる可能性が高い。また、ソーシャルメディアとメンタルヘルスの関連性を研究する流れと合流し、テクノロジー企業に対する社会的責任の議論をさらに加熱させるだろう。特にAppleは、製品の使用時間管理機能を強化する動きを既に示しているが、こうした研究結果が政策立案者の注意を引くことは避けられない。

長期的視点

1〜3年のスパンでは、スマートフォン依存と人口動態の関係が、公衆衛生や労働政策の領域で本格的に議論されるようになると見られる。出生率低下は先進国共通の課題であり、技術の普及がもたらす意図せざる結果として、テクノロジー企業は製品設計の段階から社会的影響を考慮する必要性が問われている。また、この研究手法は、AIアシスタントやソーシャルメディアの普及が人間関係に与える影響を評価するためのモデルケースとなる可能性がある。

編集部からの問い

スマートフォンやソーシャルプラットフォームが人間の生殖行動や家族形成に与える影響を、企業はどの程度まで責任を持つべきか。また、今回の研究は「相関ではなく因果」を主張するが、観察研究ゆえの限界も存在する。さらに、テクノロジーの利便性と社会的コストのトレードオフを、私たちはどのような指標で評価すべきなのか。これらの論点は、単なる経済学の枠を超えて、テクノロジーと人間の関係そのものを再考する契機となるだろう。

参考

If your sex life is dead, you can blame Steve Jobs - The Register — 2026-06-09公開
NBER Working Paper (該当論文)

Frequently Asked Questions

この研究はiPhoneがなければ出生率は低下しなかったと主張しているのか: 研究は「iPhoneの普及が出生率低下に大きな因果関係を持つ」と示唆しているが、経済的不安や住宅費など他の要因も同時に作用していると認めている。iPhoneへのアクセスが出生率低下の最大52％を説明する可能性があると試算したが、残りの部分は他の要因に起因すると見ている。
なぜAndroid端末ではなくiPhoneに焦点が当てられているのか: 2007年から2011年までiPhoneはAT&Tのみで販売され、地域によってアクセス可否が明確に分かれたことが「自然実験」として理想的だったため。Android端末は複数のキャリアで同時に普及したため、同様のクリーンな比較が難しかった。
この研究結果は日本にも当てはまるのか: 研究は米国のデータに基づいており、日本に直接適用できるかは不明。ただし、スマートフォンの普及と出生率低下の関係は、文化的・経済的背景が異なる国でも類似のパターンが存在する可能性があり、今後の国際比較研究が待たれる。TITLE: iPhone Adoption Linked to U.S. Birth Rate Decline, NBER Study Suggests EXCERPT: An NBER working paper reports a "large and causal relationship" between iPhone adoption and declining U.S. birth rates. Analyzing data from the AT&T exclusivity era, it found notable declines among younger women. TAGS: iPhone, birth rate, economics, technology and society, mobile BODY: U.S. birth rates have been declining for nearly two decades, but economists have identified a new factor: the spread of the iPhone. According to a working paper from the National Bureau of Economic Research (NBER), comparing AT&T's mobile broadband coverage with county-level birth data from the 2007 iPhone launch until AT&T lost its exclusive sales rights in 2011 suggests a significant causal link between iPhone access and lower birth rates. The paper, authored by Caitlin Myers, an economics professor at Middlebury College and NBER research associate, and graduate student Ezekiel Hooper, concludes that counties with access to the iPhone via AT&T experienced a sharper decline in births compared to those without. "It's nearly impossible to deny that birth rates fell faster in areas with AT&T coverage," Myers told The Register. ## Research Methods and Results The researchers statistically controlled for confounding factors such as income, race, and education, and compared areas dominated by Verizon or Sprint (where the iPhone was effectively unavailable until Android devices became widespread) as a control group. They observed birth rate declines of up to 8% among women aged 15-19 and up to 6.6% among those aged 20-24. Statistically significant but smaller declines were also seen in older age groups. "Taken together, these cohort effects suggest that iPhone adoption deepened birth declines among women under 30 while simultaneously suppressing birth increases among older women," the paper explains. It further estimates that up to 52% of the overall decline in U.S. birth rates during that period could be attributable to iPhone adoption. ## Comparison with Control Group After Android devices began to spread widely in 2009, signs of declining birth rates also emerged in control areas, but the authors note that small sample sizes and limited data make conclusions less precise. "As a scientist, I hesitate to say it's 'proven,'" Myers said. "But I think we've identified a compelling natural experiment, and it strongly suggests a large and causal relationship between the iPhone and birth rates." ## Background and Industry Reactions U.S. birth rates have been consistently declining since 2007, with factors such as economic uncertainty, rising housing costs, and shifting career priorities cited. This study is notable for statistically demonstrating that the immersive experience of mobile devices may have reduced face-to-face interactions and opportunities for young people to meet, thereby affecting birth rates. In a LinkedIn post, Hooper noted that people he discussed the paper with were not at all surprised. "Counties with iPhone access were adjacent to those without. Teen and young adult birth rates fell faster in places where iPhones were available," he explained. ## Editorial Perspective ## Short-Term Impact The significance of this research lies in its quantitative capture of the social changes triggered by smartphone adoption. Over the next three to six months, similar analyses are likely to be attempted in other countries. It will also merge with ongoing research on the link between social media and mental health, further heating up the debate on tech companies' social responsibility. Apple has already moved to strengthen screen time management features, but such findings are bound to draw policymakers' attention. ## Long-Term Outlook Over a one- to three-year span, the relationship between smartphone dependence and demographics is expected to become a serious topic in public health and labor policy discussions. Declining birth rates are a common challenge for developed nations, and as an unintended consequence of technology diffusion, tech companies are being called upon to consider social impacts from the product design stage. Furthermore, this research method could serve as a model for evaluating the influence of AI assistants and social media on human relationships. ## Questions from the Editorial Team To what extent should companies be responsible for the impact of smartphones and social platforms on human reproductive behavior and family formation? While this study claims "causation, not just correlation," it also has the inherent limitations of observational research. Moreover, what metrics should we use to evaluate the trade-off between technological convenience and social costs? These issues go beyond economics, prompting a rethinking of the very relationship between technology and humanity. ## References - [If your sex life is dead, you can blame Steve Jobs - The Register](https://www.theregister.com/personal-tech/2026/06/09/study-links-iphone-rollout-to-decline-in-us-birth-rates/) — Published June 9, 2026 - NBER Working Paper (the relevant paper) FA
Does this study claim birth rates would not have declined without the iPhone?: The study suggests "the iPhone's spread has a large causal relationship with declining birth rates" but acknowledges that other factors such as economic uncertainty and housing costs are also at play. It estimates iPhone access may explain up to 52% of the decline, attributing the remainder to other causes.
Why focus on the iPhone rather than Android devices?: From 2007 to 2011, the iPhone was sold exclusively through AT&T, creating a clear natural experiment where access varied regionally. Android devices spread simultaneously across multiple carriers, making it harder to perform a similarly clean comparison.
Do these findings apply to Japan?: The study is based on U.S. data, and its direct applicability to Japan is unclear. However, a similar relationship between smartphone adoption and birth rate declines may exist in countries with different cultural and economic backgrounds, pending future international comparative research.

Source: The Register

Written by Takumi Matsumoto

Edited & reviewed by Kenichiro Yamamoto

Last updated: June 9, 2026

If you find any factual errors or inaccuracies, we will promptly publish a correction. Please contact us via the contact form to request a correction.