TIE IMMIGRATION TO BIRTH RATE

Does the rising number of births to American women herald a new "baby boom" ? Final figures for 1989 may well show that annual births have risen from their 1976 low of 3.1 million to 4 million, the highest since 1964.

Demographers have tended to minimize this increase, noting that large numbers of baby boom women are now in their child-bearing years, but that they are not necessarily averaging more births.Recent data cast doubt on that explanation. A 1989 census Bureau projection foresaw just over 3.7 million births in 1990 if the total fertility rate remained at its longstanding level of 1.8 births per woman. But the actual number is likely to surpass 4 million because of the 1988 rise in the total fertility rate to 1.94, the highest since the early 1970s. A total fertility rate of 2.0 for 1989 is quite possible.

The United States thus would be following a trend now apparent in some European countries, where fertility is now rebounding. Sweden's total fertility rate, for example, bottomed out in 1978 at 1.6, and has just reached 2.0.

The increase in fertility could be temporary. It may be that, by coincidence, an unusual number of women over 35 as well as younger women may be having their first births at the same time. If so, the total fertility rate would be artificially high.

Current population estimates, the "denominator" used in calculating rates, also may be too low. Population statistics on which all vital measurements are based are from Census estimates, which can be off. The rates calculated in the late 1970s turned out to be artificially high: the 1980 census counted 5 million more people than expected.

More likely is that the rising total fertility rate simply indicates a genuine rise in fertility, regardless of age. Higher fertility among the growing proportion of minorities, particularly Hispanics, may be contributing to the increase.

What would climbing fertility mean for the future size of the U.S. population? At first glance, an increase from an average of 1.8 births to 2.0 births seems modest. It isn't. Such a slight change can have an impressive cumulative impact. Assuming that net yearly immigration remains constant at 800,000, life expectancy eventually rises to 81 years and fertility stays at 1.8, the nation's population would increase from its present 251 million to 272 million by the year 2000 and 318 million in 2030.

However, if fertility were to rise to 2.0, those population milestones become 274 million in 2000 and 334 million in 2030. In just 40 years, the small rise in fertility would yield 16 million additional more people in the United States.

Even slight increases in fertility have implications for immigration policy, particularly for those concerned about unending population growth. As these data indicate, zero population growth is not on the horizon. Even if net immigration were reduced from 800,000 to 500,000 per year, a total fertility rate of 2.0 would yield a population of 270 million in 2000 and 316 million in 2030.

Any improvements in life expectancy - the United States now ranks low among advanced countries - would of course add tens of millions more to the population by 2080.

Consideration of immigration reform in Congress now centers on two bills, both of which would substantially increase intake. Both bills would better

serve a national need by explicitly taking into account the demographic effects of optional immigration levels.

In a democratic society, fertility cannot be manipulated and life expectancy cannot be decreed. Immigration remains as the only demographic variable that can be controlled through legislation. Those controls should be tied to the shifts occurring in the other two demographic variables: fertility and mortality.

The nation needs an overall population policy. Should zero growth be a goal? If so, at what level? Should continued growth be encouraged? If so, up to what level? If such a policy were in place, establishing levels of immigration would become a far less complex and disjointed legislative process.

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