The enduring mystery of the fertility decline has a new culprit: the smartphone.
Experts have long wondered if phones played a role in the birthrate decline — which began in 2007, the same year that Apple introduced the iPhone — but until now there had not been hard evidence to prove it.
Two new papers, one published Monday and the other in May, are the first academic endeavors that test whether the smartphone was a cause.
They are the most recent efforts to explain the sweeping fertility rate decline in the United States and other countries over the past 20 years. Researchers have already looked at contraception use, abortion rates, rising levels of female education and even the popular television show “16 and Pregnant.”
Proving phones caused the decline is a tricky endeavor. There were a number of major events in those years, including the Great Recession, and isolating smartphone use is difficult.
The gold standard for scientific evidence is known as random assignment. It compares outcomes for people randomly chosen to receive a treatment (like getting a smartphone) with people who are not.
But that is not possible when it comes to ferreting out reasons for declining fertility.
So researchers sought out data about smartphones that introduced randomness.
Caitlin Myers, an economist at Middlebury College, and Ezekiel Hooper, her student, used the spotty early rollout of the iPhone as a way to isolate the effects of the phone on fertility. The first iPhone was released in June 2007, they wrote, and was available only on the AT&T network until February 2011. The study compared fertility rates in U.S. counties that had near-universal AT&T coverage with counties that had little or none.
Their paper, published in the National Bureau of Economic Research, found that the iPhone caused as much as half of the fertility decline between 2007 and 2011. The most pronounced effects were among young people aged 15 to 24.
What happened in the counties with iPhones? One theory, Professor Myers said, is that young people began to socialize more on their phones and less in person, and consequently were less likely to have sex and become pregnant.
Professor Myers said iPhones may also have made pornography more accessible, which led young people to substitute it for sex, or young people may have used them to obtain better information on avoiding pregnancy, including contraception and abortion.
Researchers not involved in the study said the results were persuasive.
Phillip B. Levine, an economist at Wellesley College, said he was “a little jealous” of the Middlebury data, which he said provided a real insight into a potential driver of a major social change.
He said some variation in the AT&T data could throw off the final finding. For example, the company may have set up in counties that were wealthier, or more densely populated, introducing a pattern “that’s not likely to be random anymore,” he said.
He said that Professor Myers tried to account for those variations, and that her findings made sense.
But, he cautioned: “You shouldn’t take the result so literally and say: Oh, it’s the iPhone’s fault. It’s an example of the kinds of social influences that have led to the decline in birth rate.”
Dropping birthrates, once a feature of rich societies, are now a near-global phenomenon. The sweep of the decline has researchers looking for common drivers. The authors of the second study also decided to look at smartphones.
“Countries with very different health care systems, welfare regimes, abortion laws, religious traditions, recessions and demographic trends all saw similar breaks in the same window,” wrote the authors, Hernan Moscoso Boedo, an economics professor at the University of Cincinnati and Nathan Hudson, a Ph.D. student.
“Whatever caused it was something global — something that arrived in roughly the same form in all of these places at roughly the same time,” they wrote.
They analyzed World Bank data measuring smartphone penetration and teenage fertility rates in 128 countries. In countries as varied as Iran, Costa Rica, Guatemala, Chile, Mexico and Turkey, they found that teenage fertility declines accelerated once smartphones became a mass phenomenon.
They tested their technology theory in the United States using data on wired broadband and 4G high-speed mobile networks. They looked at where access was better and worse and found a substantial effect: that fertility rates for teenagers declined fastest in counties with more high-speed access.
Theodore Joyce, an economist at Baruch College, said he was skeptical of both studies. Teenage births have been falling since the 1990s, he said, long before technology came on the scene. Professor Myers’s paper, he said, examined a short period before smartphones had fully penetrated.
The hypothesis, he said, could be correct but “remains speculative.”
