Developing an Original Theoretical Framework for Nigeria’s Second Demographic Transition

The Second Demographic Transition theory describes the shift from high fertility and mortality to new forms of family formation including delayed marriage, cohabitation, and declining fertility driven by individualisation, and while this transition has been theorised for Western countries, its applicability and required adaptation for the Nigerian demographic context represents an important original scholarly contribution. This study developed an original theoretical framework for Nigeria's Second Demographic Transition, drawing on demographic theory, empirical evidence from urban South West Nigeria, and critical engagement with SDT theory in African contexts. A theory-building methodology was employed, combining systematic review of 84 SDT and African fertility publications from 2018 to 2024, empirical survey data from 1,200 adults in Lagos and Ibadan on partnership patterns, fertility intentions, and individualisation indices, and expert consultation with 20 demographers and family sociologists. The systematic review confirmed that SDT theoretical constructs assume a completed First Demographic Transition, that SDT's individualisation driver has distinctive manifestations in African collectivist cultural contexts, and that the Nigerian evidence shows segmented transition dynamics (SDT elements in educated urban populations concurrent with stagnant demographic patterns in rural northern populations). The original Nigerian SDT Continuum Framework proposes a four-stage segmented transition model that accounts for the co-existence of multiple demographic regimes within a single country, driven by socioeconomic stratification rather than uniform post-materialist value shift. Expert review by 22 demographic transition theorists confirmed the framework's original theoretical contribution.

Keywords: Second Demographic Transition, Nigeria, demographic theory, fertility decline, original framework