What would BEST account for the lack of population in the southwestern portion of Africa?

It has the highest birthrate and will triple its population by 2050. "There is a lack of appropriate infrastructure, health care, access to hospitals, education and jobs for these people," Kaps said, outlining the dilemma many African countries will face in the future. Despite waning infant mortality, the average birthrate of 4.7 children per woman remains high when compared with the rest of the world.