Caught in Transit: Identifying Stalls in Fertility Transitions Using a Probabilistic Approach

Mark Wheldon, United Nations Population Division
Vladimira Kantorova, United Nations
Joseph Molitoris, United Nations Population Division
Patrick Gerland, United Nations Population Division
Yumiko Kamiya, United Nations

Possible stalls in fertility transitions, especially in sub-Saharan Africa, have been discussed frequently in the demography literature. However, the various methods used to identify stalls were limited by a reliance on irregular inter-survey intervals, inconsistent definitions, and a failure to account for measurement uncertainty. We propose a new, probabilistic approach for identifying fertility transition stalls based on the results from the 2024 revision of World Population Prospects (United Nations, 2024) and apply it to all countries for the periods when total fertility is above 2.1 live births per woman. Our method is not restricted to inter-survey intervals, uses all available data from all available data sources, incorporates biases and measurement errors, and provides probabilistic estimates of fertility stalls. We compare our findings for sub-Saharan Africa to those in the literature and find that the probability of many previously identified stalls is probably quite low based on the data available. We also identify several stalls (or reversals) in fertility decline across all regions since 1950 and discuss some of the potential reasons causing these changes in fertility trends.

Keywords: Data and Methods, Population projections, forecasts, and estimations, Bayesian methods , Fertility

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