Understanding demographic events and migration patterns in two urban slums of Nairobi City in Kenya

Understanding the dynamics of movements between different demographic events is essential for informing effective population management strategies. This study aims to characterize the trajectories of demographic and other vital events within the Nairobi Urban Health and Demographic Surveillance System (NUHDSS). Thus, it intends to unravel patterns and trends that can guide the development of targeted policies and interventions to address the population's evolving needs. Using a continuous-time homogeneous multi-state Markov model, longitudinal data from 223,350 individuals in Korogocho and Viwandani urban slums, we study the enumeration, births, deaths, and migrations among urban poor in Nairobi, shedding light on population dynamics and movements over time, disaggregated by gender. Findings indicate a positive net migration in population per thousand in 2002, dropping in 2004, with Viwandani consistently showing higher birth rates than Korogocho. Males generally have higher death rates than females. Females from Viwandani are 39.0% more likely to exit after enumeration compared to Korogocho, while males are 35.6% more likely to move from enumeration to exit compared to males from Korogocho. Both genders from Viwandani have a decreased likelihood of moving from birth to death compared to Korogocho. Our findings provide unique insights into migration in urban Kenya, the frequency and movement to different demographic events and any gender differences that warrant strategic policies for effective population and health planning in Africa. These findings can inform the design of effective health interventions that are often affected by migration and population growth.