The arrival of smartphones may have played a direct role in the sharp decline in U.S. fertility after 2007. The theory is not that phones biologically reduced fertility, but that they changed the social conditions under which dating, sex, partnership, and family formation occur. Less in-person contact, more screen time, altered adolescent social life, and delayed intimacy may all have contributed to fewer births.
A working paper by economist Caitlin Myers of Middlebury College and the National Bureau of Economic Research examined early AT&T mobile broadband coverage to determin where the first iPhones could function. Counties with broad early smartphone access saw larger fertility declines from 2007 to 2011 than counties with limited access. The effect was especially strong among teenagers: birth rates for girls ages 15 to 19 fell about 26% in high-access counties, compared with 14% in low-access counties.
The smartphone hypothesis does not replace other explanations. Housing costs, childcare expenses, student debt, delayed marriage, economic uncertainty, contraception, education, and changing gender expectations all shape fertility. But the data add a striking new possibility: digital technology may have changed the most intimate patterns of social life faster than demographers realized.