Fertility Transition Across Major Sub-Saharan African Cities: The Role of Proximate Determinants

Abstract Background Sub-Saharan Africa’s fertility transition has lagged behind other regions despite rapid urbanization, resulting in persistently high fertility rates. Studies on fertility transitions in African cities remain scarce. This study examines the stages of fertility transition across major sub-Saharan African cities and analyzes the impact of key proximate determinants on fertility rate differences among these major cities. Methods This analysis used Demographic and Health Survey (DHS) data from 19 cities with populations over 1 million, classifying cities into four fertility transition stages: post-transition (TFR < 2.1), late-transition (TFR 2.1–2.99), mid-transition (TFR 3.0–3.99), and upper mid-transition (TFR ≥ 4.0). The Bongaarts’ Proximate Determinants model was applied to examine the contributions of marriage, contraception, Postpartum Infecundability (PPI), and abortion to fertility differences across these stages. Results Among the 19 cities studied, only one city falls into the post-transition stage, six in the late-transition, eight in the mid-transition, and four in the upper mid-transition. Marriage rates are lowest in post-transition cities (34.3%) compared to 52–56% in the other stages. Contraceptive use is highest in post-transition at 50.1% and lower at 45.2%, 38.4%, and 21.3% in late-transition, mid-transition, and upper mid-transition cities, respectively. Marriage rates account for the largest portion of the TFR difference between post-transition and late-transition cities (38%), while contraceptive use explains only 2.8% of this gap. Together, marriage and contraceptive use account for 45–60% of the TFR difference between post-transition cities and those in the mid- and upper mid-transition stages. Between late-transition and mid/upper mid-transition cities, contraceptive use explains up to 32% of the TFR difference. Abortion has minimal impact, while PPI slightly offsets fertility differences across the transition groups. Conclusion Most cities in this study were in mid- or late-transition stages, with contraceptive use and marriage rates central to fertility differences. In earlier stages, increased contraceptive use significantly reduces fertility, advancing cities through initial transition phases. However, as cities shift from late to post-transition stages, contraceptive influence declines, and lower marriage rates become dominant, illustrating that a complex interplay between family planning services and cultural shifts around marriage drives fertility transition in the region.