The Long‐Term Trends in Cohort Fertility: Global, Regional and National Estimates and Projections for Cohorts Born in 1935–2055

Abstract This study presents the first global dataset of fertility estimates and projections for cohorts of women born between 1935 and 2055. Leveraging the World Population Prospects 2024 revision, which provides single‐year single‐age fertility indicators for 1950–2100, we reconstructed cohort fertility profiles for all countries. These data offer a unique opportunity to analyze cohorts that have completed childbearing and those entering reproductive ages, extending analyses beyond countries traditionally covered by the Human Fertility Database (HFD). Cohort measures were derived by transforming period age‐specific fertility rates into Lexis triangles and aggregating them into cohort parallelograms, following HFD methodology. Validation against observed cohort data confirmed high accuracy of our estimates. Results revealed that cohort fertility declines have been more gradual than period declines, with substantial regional heterogeneity. Europe and Northern America reached replacement‐level cohort fertility with the 1946 cohort, while sub‐Saharan Africa is projected to remain above 2.3 births per woman for the 2055 cohort. In low‐fertility countries, completed cohort fertility is projected to fall below 1.5 births for the 1983 cohort in many cases. These findings underscore the stability of cohort measures compared to period indicators and highlight their value for understanding long‐term fertility dynamics and informing demographic research and policy.