Fertility and urban context: A case study from Ghana, West Africa, using remotely sensed imagery and GIS

Sub-Saharan Africa has the highest levels of fertility in the world, despite rapid urban growth in most nations of the region. While there are many reasons for the fact that fertility decline is slow in Africa, we hypothesize that the relationship between fertility and urbanization is obscured by the fact that urbanization takes place along a gradient. In the most urban places (e.g., neighborhoods of the largest cities), fertility is apt to be very low, but most urban residents are residing in places that are somewhere along a continuum from completely rural to the most urban possible. All previous attempts to define that urban gradient and relate it to fertility levels rely in one form or another on census data. Because sub-Saharan-African countries are among the least prolific in terms of census gathering, a measure that relies solely on satellite imagery to gage a place's position along the urban gradient could be extremely useful. This paper describes a methodology for doing this and then uses data from the West African country of Ghana to examine how spatial patterns of land cover are associated with fertility. Satellite imagery and landscape metrics are used to create an urban context definition based on landscape patterns using a gradient approach. Census data are used to model the association between urban context and fertility through ordinary least square regression and spatial autoregressive models. Results indicate that there are significant differences in fertility between different urban contexts.