Smartphones drove teen fertility collapse

A cross‑national paper argues teen births fell sharply beginning around 2007 because smartphones rewired teen social networks: in‑person unstructured contact — where most unintended conceptions occur — declined as phone‑mediated interaction became the peer equilibrium. The authors use variation in terrain‑driven 4G/broadband coverage as an instrument, time‑use diaries showing halved in‑person socializing and tripled digital leisure, and parallel results from England and Wales to support a causal story. — If true, this reframes a major demographic trend as a technology‑driven coordination shift with consequences for population dynamics, youth mental health, and policy on digital access and adolescent services.