Birthrate refers to the average number of offspring born to each person (or, more practically, to each woman) within a given population over the course of each individual's lifetime. When the birthrate goes below 1.0, the population is declining.
Birthrate in general is an issue because long-range planning is strongly affected by the age-mix (roughly: how many working-age people for each old person) of the population, and the age-mix is directly affected by the birthrate.
For centuries the primary worry over birthrate has been the Malthusian prediction (An Essay on the Principle of Population, 1798) that a continually growing population must eventually exceed the resources available to feed it, resulting in eventual disaster. In recent decades, however, it has become apparent that increasing education and personal wealth lead to a gradual decline in birthrate, to the point where the global population is currently expected to peak at about 8 billion in 2050 or so and then decline to 5.5 billion – less than the current (2007) population – in 2100.
While this is overall a pleasant picture, it does cause some practical short-term and medium-term crises. The real-estate industry in the United States, for example, which is driven largely by an accelerating need for new housing and office space, may suffer a severe decline or collapse when the demand ceases to accelerate and eventually begins to decrease.
Another worry, which possibly arose around the same time as the Malthusian prediction of disaster, is the worry that "all the wrong people are having babies" – i.e. the people whom we least want to have more of (the poor and hence uneducated) are the ones who are breeding the fastest. This is currently manifested in the worry that immigrant Muslims are not only out-breeding native Europeans but also successfully preventing their children from integrating into European/Western society, which seems to lead inevitably to a Muslim takeover of Europe within a generation or two. (Hard data on this issue are currently difficult to come by.)
- 2007-08-04 Birth rate crisis hits Central Europe: "Population levels across many parts of the developed world are declining, but this is particularly noticeable in former Eastern Bloc states where the number of children being born has plummeted within a generation."