An analysis of its implications Zero Population Growth in Michigan KURT GORWITZ, ScD, and CH. MUHAMMAD SIDDIQUE, MSPH DESPITE a substantial de- ognized is zero population growth a balance between the two would crease in birth and fertility (ZPG), a term that within a few be reached that essentially would rates, the number of Michigan years has become part of the remain unchanged. residents has been increasing 1 English language. ZPG has been We define and describe certain percent annually because of an defined by some as an immediate assumptions related to the ZPG excess of births over deaths. In- balance between live births and concept and consider some impli- migration and outmigration have deaths, but such a balance would cations for Michigan should this been virtually in balance. Mich- not be attainable for some time concept become reality. In this igan, as well as the United States, because it would limit women to paper we do not take a stand for currently has nearly twice as an average of 1.3 children, or or against ZPG. Our purpose is many births as deaths. This approximately half the current limited to promoting an aware- growth in population, if un- average of 2.56 children. (Cur- ness of the important changes checked, would lead to a dou- rent in this report refers to 1970.) that can be expected with popula- bling of the State's population in We employ the more realistic tion stability. 60 years. In a number of foreign ZPG concept that each generation countries and among some seg- of women should reproduce only Analysis of the Data ments of the U.S. population, the enough children to establish an Between 1960 and 1970, the annual growth rate has been 3.5 eventual balance between live number of Michigan residents in- percent, which produces a dou- births and deaths. Based on cur- creased more than 1 million, or bling of the population every 20 rent survivorship rates in Mich- 13.4 percent, from 7,823,194 to years. igan, the number would be 2.11 8,875,083. Proportionally, this Awareness of the dangers in- children per woman. This aver- growth was almost identical to herent in uncontrolled growth has age is slightly more than two, re- that of the U.S. population, and led to a number of proposals for flecting early mortality and the 97.4 percent of it was the result checking or reducing this expan- ratio of male to female births of an excess of live births over sion. One of the most widely rec- (1.04: 1.00). A reduction of deaths. Net inmigration of 151,- 18.4 percent, or 139,170 births, 000 nonwhites slightly exceeded Dr. Gorwitz is chief of the center rather than the 170,510 births the net outmigration of 124,000 for health statistics, Michigan De- reported in 1970, would decrease whites; the difference accounted partment of Public Health. Mr. the annual fertility rate from the for the remaining 2.6 percent of Siddique, a candidate for the current 85.3 births to 70.3 per increase. If this growth rate were MSPH degree at the University 1,000 women aged 15 to 44 to continue, Michigan's popula- of North Carolina School of Pub- years. tion would total 10.1 million in lic Health at the time of the If women were to continue 1980, 13 million in 2000, 16.7 study, received his field train, having 2.11 children, a gradual million in 2020, and 21.5 million ing at the center. Tearsheet re- aging of the population would in 2040. quests to Center for Health Sta- occur, with a resultant decrease In projecting the effect of zero tistics, Michigan Department of in the number of births and a population growth on Michigan's Public Health, 3500 North concomitant increase in deaths. future population size, we as- Logan, Lansing, Mich. 48914. Ultimately, around the year 2030, sumed that- August-September 1972, Vol. 87, No. 7 617 1. Inmigration will equal out- Table 2. Age-specific birth rates per 1,000 women, by age groups migration. and adjusted age-specific birth rates on a ZPG basis, Michigan, 1970 The two have balanced in re- Age group of mother Birth rate Adjusted cent years, although not in each (years) birth rate age group, and we do not believe that this trend will change. 10-14 ................................... 0.888 0.732 15-19 ................................... 65.020 53.569 2. Age-specific death rates for 20-24 ................................... 171.225 141.071 males and females will remain 25-29 ................................... 173.938 143.306 30-34 ................................... 64.441 53.092 constant at current levels (table 35-39 ................................... 27.319 22.508 1). 40-44 ................................... 8.914 7.344 45-491 In virtually all age and sex .................................. .553 .456 groups, death rates changed only 1 Includes a few births to mothers older than 49. negligibly during the past decade. This trend is expected to continue If the foregoing three assump- 1980, 31.8 years in 1990, 33.6 unless a cure or method of pre- tions are valid, we could then years in 2000, 35.1 years in vention is found for heart disease, anticipate that- 2010, 35.3 years in 2020, 36.3 cancer, or one or more of the 1. The number of Michigan years in 2030, to 36.3 years in other leading causes of death. residents will increase an average 2040 (table 5). These increases 3. Age-specific birth rates will of 0.5 percent per year until in age average 0.16 per year. remain constant at levels com- 2030, as compared with the cur- By 2030 a little more than 15.2 puted by multiplying all current rent annual growth rate of 1.0 percent of the population will be 2.1121 percent. 65 years old or older as com- rates by 2.56 (table 2). The current population of 9 pared with the current 8.4 per- Birth rates (table 3) have de- million should reach a maximum cent. Conversely, the proportion creased most rapidly among older of 12 million around 2030 and under 20 years old will decrease women (35-44 years) and least will remain essentially in balance from 40.3 to 28.3 percent. Those among younger women (15-19 thereafter. This is 6.9 million (or between 20 and 64 years will years). Births among older 36.5 percent) less than the 18.9 increase from the present 51.3 women are now at a low level, million residents anticipated on to 56.5 percent of the total pop- and it does not seem likely that the basis of continued current ulation. women in this age group could annual growth rates (table 4). 3. The number of residents account for a disproportionate 2. The median age of the pop- under 15 years old will decrease share of further decreases in the ulation will increase from 26.5 4.9 percent by 2030. All other number of births. years in 1970 to 28.3 years in age groups will increase: 15 to 24 years, 1 percent; 25 to 44 50.8 45 1. death rates estimated years, percent; to 64 Table Age-specific per 1,000 population, years, 62.7 84 and sex 1970 percent; 65 to by age groups, Michigan, years, 151.2 percent; 85 years Age group (years) Total Male Female and over, 43.9 percent. The largest percentage increase Under 1 .............................. 21.65 24.72 18.47 will be for the group between 65 1-4 ................................ .85 .97 .73 5-9 ............................... .45 .54 .36 and 84 years, but the largest 10-14 ................................ .40 .49 .31 numerical increase will be for 15-19 ................................ 1.11 1.63 .58 20-24 ............................... 1.43 2.33 .64 those between 25 and 44 years. 25-29 ............................... 1.66 2.28 1.10 This younger group accounted 30-34 ............................... 1.40 1.87 .96 35-39 ............................... 2.06 2.55 1.61 for 24.7 percent of the total pop- 40 44 ................................ 3.80 4.78 2.81 ulation in 1970 and is expected 45-49 ............................... 6.18 7.80 4.60 50-54 ................................ 9.84 12.76 6.97 to include 27.5 percent of all 55-59 ................................ 13.77 18.48 9.27 residents in 2030. 60-64 ............................... 20.47 27.89 13.59 65-69 ............................... 31.72 41.01 22.98 4. The ratio of dependent pop- 70-74 ............................... 49.17 61.47 38.22 75-79 ............................... 66.13 86.51 51.48 ulation (under 20 years and 65 80-84 ............................... 112.46 140.32 94.67 years or over) to working-age 85 or over ............................ 193.03 212.98 181.70 population (20 to 64 years) will 618 Health Services Reports decrease from 0.95 to 1 in 1970 Table 4. Projected population, based on current growth rate and zero to 0.77 to 1 in 2030. population growth, Michigan, 1979-2040 changing ratio reflects the This Projected population Difference sum of two divergent trends. Year Based on current Based on While the ratio of older to work- growth rate ZPG Number Percent ing-age population will increase (from 0.16 to 1 in 1970 to 0.27 1970 .............. 8,901,381 8,901,381 ................. 1980 ............... 10,068,306 9,607,064 461,242 4.6 to 1 in 2030), the ratio of 1990 .............. 11,422,084 10,421,627 1,000,457 8.8 younger to working-age popula- 2000 ............... 12,957,881 11,026,545 1,931,336 14.9 to 2010 .............