Mathematical Model and Analysis of the Effects of Social Determinants of Health Contributing to Teenage fertility in Kenya

Abstract

Teenage pregnancy remains a significant public health challenge in Kenya, with adolescent sexual and reproductive health needs largely unmet, especially among marginalized and vulnerable groups. Although the 2022 Kenya Demographic Health Survey (KDHS) reports a slight decline in teen pregnancy from 18% in 2014 to 15% in 2022, progress toward achieving Kenya Vision 2030 remains slow. Understanding the effects of social determinants on teenage fertility through rigorous mathematical modeling is essential for informing effective interventions and policy actions. This study develops and analyzes a deterministic differential equations model incorporating demographic, socio-economic, and socio-cultural factors affecting adolescent fertility among females aged 15-19 years using KDHS 2022 data. In this model, qualitative theory of differential equations and stability analysis has been used to assess the impact of proximate determinants on fertility outcomes. Stability analysis reveals that both eigenvalues, λ1 = −β and λ2 = −δ, are negative, establishing that the system’s equilibrium is asymptotically stable. Sensitivity analysis further identifies that the decay parameters β and δ exert strong negative influence on the fertility reproduction potential R0, highlighting critical social determinants that significantly influence teenage fertility rates. These insights allow prioritization of intervention strategies targeting the most impactful factors. Importantly, the model demonstrates that targeted policy interventions can effectively shift the system to a new, lower equilibrium teenage fertility rate, providing valuable guidance for policymakers. Ethical approval for this study was obtained from the National Commission for Science, Technology and Innovation in Kenya, ensuring adherence to national research ethics guidelines. The findings provide robust, evidence-based insights for government and stakeholders to design impactful strategies to reduce teenage pregnancies in Kenya.