Why is there a high population growth rate in African countries despite high mortality rates?

Mortality in Africa is high due to hunger, epidemics, poor medicine and natural disasters. However, even in the poorest and most underdeveloped countries, there is a high birth rate. On average, about 40-45 ppm, which roughly corresponds to the level of Russia at the beginning of the 20th century or the 1920s. That is, a traditional agrarian society, where even a high mortality rate due to epidemics, wars and hunger is overridden by natural population growth.