“…For instance, in times when fertility has been massively delayed, the question of how social age deadlines for reproduction have changed becomes particularly relevant. There is a vast body of literature examining social age norms for childbearing at one point in time (Billari et al, 2011;Liefbroer and Merz, 2009;Kim and Cho, 2021;Paksi and Szalma, 2009; Van Bavel and Nitsche, 2013), but less attention has been devoted to their temporal variation. We take inspiration from the research by Billari et al, (2021) who documented how social age norms have become more favourable to the later timing of childbearing across European countries using two rounds of the European Social Surveys (ESS) collected in 2006-07 and 2018-19. We extend this evidence, focusing on the extent of social normative change in 21 national contexts, comparing indicators of men's and women's childbearing age norms, introducing the concept of perceived reproductive window, and linking shifts in norms to observed changes in fertility.…”