Reading round today about the reasons behind the fertility decline I found the extract posted below. The only developed country anywhere near achieving even zero population growth on a stable basis is the US, and this is on the basis of levels of immigration which are extraordinarily high by recent historical standards. Don't we need to reexamine the idea of the demographic transition as it is understood by 95% of currently active economists?
The concept of demographic transition stipulates a shift from a homeostatic near-equilibrium of high mortality and high fertility resulting in zero or slow and fluctuating population growth to a new homeostatic equilibrium of low mortality and replacement-level fertility leading to a stationary population. In reality, however, fertility did not stabilize at replacement level in most countries but declined to levels far below replacement. While in some countries, this development has already led to negative population growth in others these trends suggest negative population growth and an even older population structure in the future.
Period fertility rates in all of Europe, all of Eastern Asia (except Mongolia), Canada and developed Oceania are currently at or below replacement level of 2.1 children per woman. Below replacement fertility is also evident in four (Armenia, Azerbaijan, Kazakhstan, Georgia) out of seven Asian successor States of the former U.S.S.R, Cyprus, Thailand, six Caribbean countries (Barbados, Cuba, Guadeloupe, Martinique, Puerto Rico, Trinidad and Tobago) and two (Mauritius and Tunisia) African countries. With the demographic transition completed in China, the share of the world’s population in 2002 of countries where the total fertility rate is below 2.11 children per woman reached 39 per cent. The number of countries with estimated fertility levels at or below 2.11 children per woman increased from 5 in 1960 to 64. Moreover, recent trends of fertility in other developing countries suggest that many more countries are likely to achieve below-replacement fertility in the near future (United Nations, forthcoming). United States is the only developed country where the total fertility was recently hovering close to replacement level fertility.
Source: UN Document on Reproductive Behaviour