Monday, August 10, 2009

Can Development Help Reverse Fertility Decline?

This letter in the latest issue of Nature suggests that it can. A sample:

During the twentieth century, the global population has gone through unprecedented increases in economic and social development that coincided with substantial declines in human fertility and population growth rates1, 2. The negative association of fertility with economic and social development has therefore become one of the most solidly established and generally accepted empirical regularities in the social sciences1, 2, 3. As a result of this close connection between development and fertility decline, more than half of the global population now lives in regions with below-replacement fertility (less than 2.1 children per woman)4. In many highly developed countries, the trend towards low fertility has also been deemed irreversible5, 6, 7, 8, 9. Rapid population ageing, and in some cases the prospect of significant population decline, have therefore become a central socioeconomic concern and policy challenge10. Here we show, using new cross-sectional and longitudinal analyses of the total fertility rate and the human development index (HDI), a fundamental change in the well-established negative relationship between fertility and development as the global population entered the twenty-first century. Although development continues to promote fertility decline at low and medium HDI levels, our analyses show that at advanced HDI levels, further development can reverse the declining trend in fertility. The previously negative development–fertility relationship has become J-shaped, with the HDI being positively associated with fertility among highly developed countries. This reversal of fertility decline as a result of continued economic and social development has the potential to slow the rates of population ageing, thereby ameliorating the social and economic problems that have been associated with the emergence and persistence of very low fertility.

....our findings are highly relevant in the debate on the future of the world's population. Whereas a decade ago Europe, North America and Japan were assumed to face very rapid population ageing and in many cases significant population declines6, 7, 21, our findings provide a different outlook for the twenty-first century. As long as the most developed countries focus on increasing the well-being of their citizens, and adequate institutions are in place, the analyses in this paper suggest that increases in development are likely to reverse fertility declines—even if we cannot expect fertility to rise again above replacement levels. As a consequence, we expect countries at the most advanced development stages to face a relatively stable population size, if not an increase in total population in cases in which immigration is substantial. For countries in which immigration is a minor component of demographic change, our analyses suggest a slower population decline than is at present foreseen in official demographic forecasts. Although significant population ageing is still certain in countries at the highest development levels, its magnitude may have been exaggerated by the widely held current perception that, as social and economic development progresses, fertility is bound to fall further. Policies targeted at further increasing HDI levels in advanced societies may therefore be suitable as a general strategy to reduce demographic imbalances caused by very low fertility levels. Consistent with current scientific knowledge, our findings also support the view that progress in development contributes to lower fertility levels in countries with low to moderately high HDI levels. Moreover, countries remaining at intermediate development levels are likely to face a decline in population size because these countries have attained low TFR levels and they do not yet—and may not in the foreseeable future—benefit from the reversal of the development–fertility relationship.