The Lancet, 14 June 2025

Human reproduction in crisis: causes unknown

Fertility rates have plummeted, making human reproduction below replacement level across all industrialised regions. In line with the tradition of demographic research, the decline in fertility rates has been assumed to reflect a cultural transition due to social and economic changes of modern times. However, this theory has not provided concrete evidence linking specific socioeconomic factors to the decline in fertility rates. Other hypotheses suggesting that lower fecundity (the biological ability to reproduce) could contribute to lower fertility rates have typically been overlooked in demographic research.

Governments have often responded to the proposals of demographic studies to lift fertility rates by providing special so-called baby bonuses. However, such programmes have not resulted in higher birth rates.