Birthrates in tropical Africa are among the highest in the world, but many zones in the region have below-norm fertility. Proximate determinants are the framework used to explain the occurrence of these zones. Of greatest significance are factors that affect duration of postpartum amenorrhea, incidences of sterility and spontaneous intrauterine abortions, and frequency of intercourse. POPULATION is growing more rapidly in tropical Africa than in any other principal world region. The average rate of natural increase there is 2.9 percent, contrasted with 2.7 percent in the Middle East and 2.6 percent in Central America, the regions with the next-highest rates. Although recent events such as famines, the AIDS epidemic, and the recrudescence of malaria have underscored the hazards to human survival in tropical Africa, mortality has fallen significantly since 1950. At the same time, fertility remains high and is increasing in some places. Total fertility rates range from 6.0 to 8.0 for tropical African countries and rise above 9.0 in portions of western Kenya. Few large populations have equaled these figures for appreciable lengths of time. Within this general pattern of high fertility are areas characterized by markedly lower total fertility rates, from 2.0 to 5.0 (Fig. 1). The most prominent of these areas lies near the equator and runs without interruption from southwestern Sudan through the Central African Republic and deep into adjacent Zaire; a second important zone covers most of Cameroon and Gabon. Other noteworthy occurrences of low fertility have been recorded in the Lake Victoria region and are scattered across the savanna-sahel belt of western Africa, as well as among the San peoples of Botswana and Namibia, for various nomadic pastoral groups, in parts of highland Ethiopia, and along the eastern coast from southern Kenya to central Tanzania. This pattern of low fertility is based on evidence obtained from several sources, including census-derived estimates on total fertility rates and childlessness levels for all of Africa south of the Sahara and surveys and estimates of total fertility rates for the equatorial zone only.1 The available evidence, however, points to a strong ethnic component in the distribution; quite often, lowand high-fertility populations are found living side by side.2 We thus 1 0. Adegbola, New Estimates of Fertility and Child Mortality in Africa, Population Studies 31 (1977): 467-486; 0. Frank, Infertility in Sub-Saharan Africa: Estimates and Implications, Population and Development Review 9 (1983): 137-144; J. C. Caldwell and P. Caldwell, The Demographic Evidence for the Incidence of Low Fertility in Tropical Africa, World Health Statistics Quarterly 36 (1983): 2-34. 2 Subfertility and Infertility in Africa (edited by B. K. Adadevoh; Ibadan: Caxton Press, 1974). * Ms. DOENGES is a graduate student in geography at Syracuse University, Syracuse, New York 13244, where DR. NEWMAN is a professor of geography. This content downloaded from 157.55.39.138 on Mon, 27 Jun 2016 06:13:29 UTC All use subject to http://about.jstor.org/terms THE GEOGRAPHICAL REVIEW