Blackwell Reference Online

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Low fertility implies a “not low” referent; there are two. The first is “high fertility.” High fertility can be defined as some maximal, hypothetical level for a population, i.e., one with early marriage, close birth spacing, and no attempt to control family size. Fifteen births per woman provides a reasonable estimate of mean maximal fertility. The highest observed levels of fertility are closer to ten births per woman, and even in the absence of substantial contraceptive use and abortion can be one-half this level. Regardless, low fertility implies much lower levels – levels approximating two or fewer births per woman. The fertility transition refers to the societal shift from “high” to “low” fertility (and is produced by deliberate attempts to achieve small family sizes). A second definition, and one emphasized in most contemporary discussions of low fertility, adopts as a referent replacement-level fertility. The concept is straightforward: a birth cohort of women replaces itself if the cohort averages one female birth per woman that survives to reproductive age. After adjustment for low levels of mortality and for normal sex ratios at birth (common features of developed countries), replacement fertility is approximately 2.1 births (male and female) per woman. Given this referent, low fertility implies levels well below what is needed for replacement. A practical weakness of ... log in or subscribe to read full text