Two new studies are pointing to an unlikely contributor to declining birthrates: the smartphone. Researchers found that fertility rates, particularly among teenagers and young adults, dropped sharply after smartphones became widely available, with one study estimating the iPhone alone may have accounted for nearly half of the decline in US births between 2007 and 2011.

Economists linked the trend to changes in behavior, suggesting young people spend more time socializing online and less time interacting in person. Smartphones may also have improved access to contraception information or changed how young people consume entertainment and relationships, contributing to fewer pregnancies.

Not all experts are convinced. Some researchers argue birthrates had already been falling long before smartphones arrived and caution that the findings show correlation rather than proof of causation. Still, similar patterns observed across 128 countries have strengthened the theory that the rise of smartphones may have reshaped one of society’s most fundamental trends.