Immigrants’ ages and the structure of stationary populations with below-replacement fertility


A sustained regime of low fertility plus immigration yields an unusual kind of stationary population. The author demonstrates that all stationary populations have a common structure, and that the familiar replacement-level fertility population is the youngest among the many stationary populations corresponding to a particular life table. This finding has important consequences for policy because although fertility increase and immigration are equally effective at halting population decline, immigration is inferior as a means of rejuvenating low-fertility populations. In fact, an immigration-based policy could make a low-fertility population older rather than younger. The paper includes examples using U.S. and West German vital rates.

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  1. Arthur, W. Brian and Thomas J. Espenshade. 1988. “Immigration Policy and Immigrants’ Ages.” Population and Development Review 14(2):315–26.

    Article  Google Scholar 

  2. Coale, Ansley J. 1987. “Demographic Effects of Below-Replacement Fertility and Their Social Implications.” Pp. 203–16 in Below-Replacement Fertility in Industrial Societies, edited by K. Davis, M.S. Bemstam, and R. Ricardo-Campbell New York: Cambridge University Press.

    Google Scholar 

  3. Council of Europe. 1990. Recent Demographic Developments in the Member States of the Council of Europe. Strasbourg.

  4. Espenshade, Thomas J., Leon F. Bouvier, and W. Brian Arthur. 1982. “Immigration and the Stable Population Model.” Demography 19:125–33.

    Article  Google Scholar 

  5. Keyfitz, Nathan. 1971. “Migration as a Means of Population Control.” Population Studies 25(1):125–33.

    Article  Google Scholar 

  6. Mitra, S. 1990. “Immigration, Below-Replacement Fertility, and Long-Term National Population Trends.” Demography 27(1):121–29.

    Article  Google Scholar 

  7. Steinmann, Gunter. 1991. “Immigration as a Remedy for Birth Dearth: The Case of West Germany.” Pp. 337–57 in Future Demographic Trends in Europe and North America, edited by Wolfgang Lutz. New York: Academic Press.

    Google Scholar 

  8. United Nations. 1989. “Method of Migration Model Construction” pp. 65-70 in World Population Prospects 1988. Sales Number E.88.XIII.7.

  9. U.S. Department of Health and Human Services. 1990. Vital Statistics of the United States 1987. Hyattsville, MD.

  10. West Germany. 1990. Statistisches lahrbuch 1990 fur die Bundesrepublik Deutschland. Stuttgart: Metzler-Poeschel.

    Google Scholar 

  11. Whitmore, G.A. and M.C. Findlay. 1978. Stochastic Dominance. Lexington, MA: Heath.

    Google Scholar 

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This research was supported by an internal grant from Florida State University. An earlier version was presented at the 1991 meetings of the Southern Demographic Association. I thank an anonymous reviewer for some very helpful comments.

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Schmertmann, C.P. Immigrants’ ages and the structure of stationary populations with below-replacement fertility. Demography 29, 595–612 (1992).

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  • Stationary Population
  • Exit Rate
  • Native Fertility
  • Replacement Fertility
  • General Stationary Population