BIRTH AND DEATH RATES<20 20–24 25–29 30–34 35–39 40–44 45+050100150200250Per 1,^000Zimbabwe
Japan
United States
Ireland82
6015218
20611140 51114 114
93
81263461106180127145803 6 13 0.1 0.3 0.731
4Figure 1. Age-Specific Fertility Rates: Selected Countries, Mid-1990s.
SOURCE: United Nations, Demographic Yearbook, 1996.
their crude birth rates which are confounded by
age-composition differences.
Although the general fertility rate is a more
accurate measure of the relative levels of fertility
between populations, it remains sensitive to the
distribution of population across women of child-
bearing ages. When women are heavily concen-
trated in the younger, more fecund ages, such as in
developing countries today and in the United
States in 1980, rather than the less fecund older
ages, such as in the United States and other devel-
oped countries today, the general fertility rate is
not the best choice for fertility analysis. It inflates
the relative level of fertility in the former popula-
tions and deflates the estimates in the latter
populations.
Age-specific fertility rates eliminate potential
distortions from age compositions. These rates are
calculated for five-year age groups beginning with
ages fifteen to nineteen and ending with ages
forty-five to forty-nine:
( 3 )X 1,000Live births in year x to women age a
Women age a in year xAge-specific fertility rate per 1,000=
Age-specific fertility rates also provide a rudi-
mentary measure of the tempo of childbearing.
The four countries in Figure 1 have distinct pat-
terns. Zimbabwe, a less-developed country with
high fertility, has higher rates at all ages. At the
other extreme, Japan’s low fertility is highly con-
centrated between the ages of twenty-five and
thirty-four, even though the Japanese rates are well
below those in Zimbabwe. In contrast, teenage
women in the United States continue to have
much higher fertility than teenage women in Ja-
pan and other industrialized countries, despite
declines in the 1990s. The younger pattern of
American fertility also is evident in the moderately
high rates for women in their early twenties. At the
other extreme, Irish women have an older pattern
of fertility.More detailed analyses of the tempo of child-
bearing require extensive information about live
birth order to make fertility rates for each age
group specific for first births, second births, third
births, and so forth (Shryock and Siegel 1976, p.
280). A comparison of these age-order-specific
rates between 1975 and 1996 reveals an on-going
shift toward later childbearing in the United States
(Ventura et al. 1998, p. 6). The first birth rate
increased for women over thirty while it decreased
for women ages twenty to twenty-four. As a result,
22 percent of all first births in 1996 occurred to
women age thirty and over, compared to only 5
percent in 1975.When the tempo of fertility is not of interest,
the advantages of age-specific fertility rates are
outweighed by the cumbersome task comparing
many rates between populations. As an alterna-
tive, each population’s age-specific rates can be