Monday, March 18, 2013

A Steady Drop in the Crude Birth Rate

In a post on Ghulf Genes a couple of days ago (link), in the context of “generations” named by popular culture, I showed a chart of the crude birth rate, thus births per 1,000 population for 1909 through 2008. In that post I wondered what the nineteenth century data might look like. Today I show a chart extending over 211 years, from 1800 through 2010.

The chart is rather instructive. The crude birth rate, which was 55 births per 1,000 people in 1800, has declined over two centuries to 13 birth per 1,000 in 2010, the lowest recorded in this time span. The rate was already dropping apace when the first reasonably effective birth-control devices were introduced in 1839, courtesy of Charles Goodyear. The “womb veil” mentioned on the graphic was the forerunner of the diaphragm. The second, call it technological, intervention came in 1960 when the FDA approved “the pill.” The third development was the legalization of abortion by the Supreme Court’s decision on Roe v. Wade in 1973—not that the public was waiting for that in the decades that came before. Technology and law aside, the phenomenon we’re seeing here is driven by cultural factors; technology and law are products of culture, not causes of demographic change.

If we fit a trend line to this curve, it becomes clear that the Baby Boom was simply a consequence of delayed opportunities for breeding, shown by the birth rate dip in the 1930s and 1940s. After the Boom, the long-term trend resumes.

Note that data for the nineteenth century are from census years only, obtained from Historical Statistics of the United States, published by the U.S. Bureau of the Census in 1975. I obtained the data from 1909 forward from a series, Vital and Health Statistics, published by the Centers for Disease Control and Prevention. This rate is called “crude” because it is a simple calculation; more refined birth rates, based on births by women in their childbearing years, the total fertility rate, requires much more careful calculation than simply dividing total population by total births.

The trend we see here underlies several “issues” that plague us, among them the aging population, the costs of maintaining such populations, and the immigration battles. Population growth in the United States is gradually having to rely on bringing population in, and, we hope, a population still willing to breed. And unless we have a growing population, we shall not have a growing market to consume the goods our machines produce.

To add more context—lest that great downward slide produces consternation—some comparisons. Of the 197 countries for which the World Bank provides data, 135 had a lower crude birth rate than the United States, 4 other countries matched our rate, and 57 had a higher rate, among them India (22). The top baby producer per 1,000 population was Niger (49). Those under-performing the U.S. included China, Russia, Japan, and all of Europe. The worst performer, with 8 per 1,000 was Germany.

The United States had a total fertility rate (TFR) of 2.1 children born to women in their child-bearing years in 2010. A TFR of 2.1 is equal the so-called replacement rate. This means that such a rate will replace all deaths in a given year. Our population, at present, is only growing by immigration. 116 counties in the world (of 197) had a higher rate, among them India (2.625), 80 had a lower rate, meaning that they were not replacing their population. Among them, again, are China, Japan, Russia, and all of Europe. The highest rate in 2010 was measured in Niger (7.06), the lowest in Macau (1.09).

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