The scientific debate around changes in fertility has focused on social, economic and cultural factors to explain the drop in total fertility rates in OECD countries. The baby boom years of the 1950s and early 1960s had come to an end following the spread of new forms of birth control like contraception from the late 1960s onwards. The trend is very obvious and yet, the explanations of the trend might lack a more profound analysis of fecundity in addition to the socio-economic explanations. Shakkebaek et al. (2025) point for example to the little known effects of environmental (pollution) factors on the biological reproduction capability of humans (men and women).
Additionally, psycho-social factors like “the German Angst” fear about future developments in many social and economic fields might have direct effects, but also indirect effects on human biology. We know still very little about such feedback loops or feedback effects. We are more convinced, than we actually have hard evidence, that the BSP, SPB or PSB (B=Bio, S=Social, P=Psycho) spheres are interwoven, but an ambitious research agenda is called for to enlighten the issue. The big invisible elephant in the room might be environmental issues that enter into the fertility equations more than we have expected for many years. A nice working hypothesis for an ambitious and overdue research agenda.
