Empirical Exploration

FROM A THEORETICAL standpoint, the lowest limit to fertility is zero. From an empirical standpoint, a more meaningful question is how low can both cohort and period fertility be in a present-day population of large size (as opposed to a small community in which one could observe abnormally low values). Mutatis mutandis it is the same question that, for high fertility, led to identification of the reproductive behavior of the Hutterites as a possible maximum of fertility in an actual population. Regarding maximum fertility, Henry (1961) defined natural fertility as fertility in the absence of deliberate birth control. Drawing on the work of Eaton and Mayer on the United States and of Henripin on Canada, among other studies, he cites a total legitimate fertility rate of 10.9 births per woman for the Hutterites (marriages from 1921-30) and of 10.8 for Canadians in the eighteenth century (marriages from 1700-30). Concerning the proportion of women who remain childless, Henry cites 4 percent in Taiwan (total fertility rate of 6.95 for women born about 1900) and 7 percent for the Fouta-Djalon in Guinea (TFR = 6.2, marriages from 1954-55). According to United Nations estimates, in contemporary African populations a period total fertility rate of 8.0 or more has been observed many times and in many countries between 1960 and 1985. A maximum was recorded for Rwanda in 1975-80 with a value of 8.5 (United Nations 1996b).