Study Finds iPhone Availability Correlates With One-Third to One-Half of U.S. Fertility Decline in Early Rollout Counties

U.S. fertility rate after its 2007 introduction. Myers compared birth rates in counties with widespread AT&T coverage, where iPhones were available from 2007 through 2011, to counties with minimal AT&T service.

Myers ran statistical checks that controlled for economic and demographic factors and found the iPhone effect remained consistent. "What we are seeing is that the places that have the iPhone have big fertility changes relative to the other places," Myers told CBS News. "I said, 'Wow, but this has to be too big,'" she recalled.

She added, "I'm not surprised that there is an effect. " Myers said the iPhone explains about a third to a half of the fertility decline over the studied short period, leaving half to two-thirds unexplained. "We're not saying it's all the iPhone.

What we are saying is that it is a really important factor to consider," she said. S. fertility rate has been in a decades-long decline. Population growth has been slowing worldwide for decades in both rich and poor countries.

The Trump administration has encouraged Americans to have more children and floated ideas such as a "baby bonus" for new parents. S. children offering federal government contributions of up to $1,000 to eligible kids.

Other countries have introduced financial incentives to increase birth rates, yet those efforts have largely failed to move the needle. Norway has seen its birth rates continue to decline over the past two decades despite generous parental programs. More states are implementing cell phone restrictions for school-age children.

On Tuesday, the Social Security Administration said the federal program is at risk of exhausting its trust fund as soon as 2023. The declining birth rate is one factor contributing to the trust fund shortfall. "It's a real concern for economic growth to have a population with fertility below replacement levels," Myers said.