Reproduction - Are We Breeding Enough To Sustain Our Numbers?

One measure of fertility tallies up the number of children born to 1,000 women during their childbearing years, 15 to 44. This is called the Total Fertility Rate (TFR). In order for a population simply to replace itself (neither to grow nor to shrink) it needs to maintain a TFR of 2,100, or 2.1 children per woman.

During the last 60 years of the 20th century the United States' TFR averaged 2,560, well over the level required to replenish our numbers. The answer to the question posed in the title of this panel is, yes. The chart shows the Total Fertility Rate each year from 1940 through 2000. The replacement level of 2,100 is highlighted with a dotted line towards the center of the graph. Wherever the TFR is above the replacement level, the society is breeding enough to at least replace its numbers. Where the TFR drops below the 2,100 line, the population is shrinking (before counting immigration and emigration). As an interesting point of reference, the infant mortality rate is also provided in the graph. This rate is the number of infants who die per 1,000 live births.

What is clear is that the TFR during the post World War II period far-exceeded population replacement levels. This was the generation that produced the Baby Boom.

On the right side of the graph, for the years 1970 through 2000, the TFR dips below replacement level for many years, slowly creeping back towards the 2,100 line and crossing it again in 2000 for the first time since 1971. This later period is the time during which the Baby Boom was reproducing. This generation was clearly less willing to raise large families than was its parents' generation.

Many factors influence the fertility rate. Industrialized countries have all seen sharp declines in their total fertility rates. Declines in fertility are understood to result from "broadening horizons for girls and women, who respond by delaying childbearing; health care advances that keep babies alive, reducing the need for more; broad availability of reliable and inexpensive family planning services; and urbanization."¹ All of these have been experienced in the United States in the 20th century.

One of the most important of these factors is our ability to control procreation. Throughout human history many methods have been used to try and prevent pregnancy. They were somewhat effective but abstinence was the only truly reliable means of preventing pregnancy… until the 1960s.

Birth control became reliable in the 1960s. Although not 100% reliable — abstinence still being the only 100% certain way to avoid pregnancy — the oral contraceptives introduced in the 1960s made it possible to engage in sexual intercourse with more than a 97% certainty that pregnancy would not occur. This marked a watershed in family planning and the beginning of sharp declines in fertility rates.

What is clear from this panel is that the TFR in the United States, after falling below the replacement level, has again reached that level in 2000. Even without the inflow of new people through immigration to the U.S., we are breeding at levels that will sustain us.

The next panel will look at another of the factors influencing fertility rates; women's growing participation in the paid workforce.

Source: U.S. Department of Health and Human Services, National Center for Health Statistics (NCHS), "Vital Statistics of the United States, 1998," Volume I, Natality, updated from later issues of National Vital Statistics Reports and Monthly Vital Statistics Reports also published by NCHS. International Planned Parenthood Federation, The Myth of Shrinking Population, September 1999, available online at http://www.ippf.org/resources/6billion/myth.htm.