EAPS Population Conference, Helsinki, 7 – 9 June 2001
Theme A Fertility, Session 1 Thursday 7 June
Heterogeneous fertility patterns in the English-speaking world. Results
from Australia, Canada, New Zealand and the United States
Version of 13 August 2001 without figures
8255 words text, 11007 including references and tables.
A shorter version of this paper was published in Population Studies 53, 3, 317 – 329
T. Chandola, Department of Public Health, University College London, D.A. Coleman,
Department of Social Policy and Social Work, University of Oxford, R.W. Hiorns,
Department of Statistics, University Of Oxford
Abstract
The paper seeks to identify common patterns in the fertility distributions of the English
speaking world. Attention is focussed on the heterogeneity within the fertility distributions of
Australia, Canada, New Zealand and the United States, similar to patterns reported earlier for
the United Kingdom and the Irish Republic. The recent age-specific fertility distributions of
these countries display a marked ‘bulge’ in fertility of women under age 25. A mixture model
with two-component Hadwiger functions provides a suitable fit. This may suggest that the
population is heterogeneous. This heterogeneity indicated by the recent fertility distributions
of the English-speaking countries is shown to be related to differences in the timing of births
by marital status, in particular the illegitimacy ratio. Additionally, in the United States and to
a lesser extent, New Zealand, there is some evidence that this heterogeneity in fertility
patterns may be explained by ethnic differences in the timing and number of births.
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Heterogeneous fertility patterns in the English-speaking world. Results from Australia,
Canada, New Zealand and the United States
Introduction
The recent fertility distributions of the UK and the Republic of Ireland have a characteristic
bulge in early age fertility not shared by most European populations, a feature first drawn to
our attention by the late M. Gérard Calot (pers. comm.) and described in detail elsewhere
(Chandola et al 1999). These asymmetries in the distribution of age-specific fertility rates
(asfr) by single year of age are apparent visually and can be described with more precision
through statistical modelling. For example, the distributions of age-specific fertility rates
observed in most Continental European populations can be fitted well by a simple Hadwiger
function (Hadwiger, 1940, Gilje, 1972). But in order to accommodate early-age excess
fertility, the UK and Irish fertility distributions and one or two others require a Hadwiger
'mixture' model with two component distributions ([Chandola et al 1999).
The English –speaking world shares various historical, cultural and demographic
characteristics. This paper will investigate whether there are common elements in the age
specific fertility distributions of the English-speaking countries overseas, similar to the
patterns noted for the UK and Republic of Ireland (Chandola et al.1999). The paper will also
explore similarities between the English-speaking countries in the possible causes of such
heterogeneous patterns of fertility by looking at differences in the timing and number of births
by marital and non-marital status and ethnicity, where the data permit.
The ‘mixture’parameters of the two-component Hadwiger mixture models (m and m-1), can
be related to the relative proportions of the two groups with different fertility characteristics
within a population. The parameter m represents the proportion of the first group in the
population; (1-m) represents the proportion of the other group. The other parameters (a1 and
a2, b1 and b2, c1 and c2) can be related to their respective total fertility rates, distributions of
births by age of mother and mean ages of the fertility schedules. The characteristics of these
two groups, inferred statistically from the model, were found to correspond reasonably well to
actual differences within each country between the sub-populations of births outside and
inside marriage, in terms of the relative number of births and their timing. Countries requiring
a mixture model to fit their fertility distributions were those where the demographic
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characteristics of births outside marriage (e.g. in respect of the mean age of fertility schedule)
were different from those within marriage (Chandola, et al 1999). Where these characteristics
were similar between births inside and outside marriage, a mixture model was not needed in
order to fit the overall distribution of age-specific fertility rates.
Historical and social background
The populations of the overseas English-speaking world overseas considered here, that is
Australia, Canada, New Zealand and the United States of America share a number of
historical, cultural and demographic characteristics common to each other and in some
respects also to the UK and the Republic of Ireland. These six countries make up two Englishspeaking groups, one European and one transoceanic. Following Crosby (1986) the
transoceanic countries will be referred to collectively as the ‘NeoEuropes’.
The English-speaking countries overseas are a well -defined group of modern developed
societies outside Europe. All have their origin in the British colonial expansion from the 16th
century and all have been, or are the constitutional successors of, colonies or dominions
under the British crown. With the exception of the early settlement of Canada by the French,
all were initially settled predominantly by emigrants from the British Isles (Great Britain and
Ireland). The preponderance of Anglo-Hibernian and Caledonian-Gallic immigration lasted
until the early 19th century in the case of the United States and in the late 20th century in
respect of the others (Baines, 1991). Emigrants from what are now Northern Ireland and the
Republic of Ireland contributed a higher proportion of this emigration. (What is now the
Republic of Ireland was part of the United Kingdom until 1921 and a member of the
Commonwealth until 1948). Since the 1960s, however, immigration patterns to all these
countries have changed radically. Emigrants from the British Isles, and indeed from Western
Europe in general, now form only a minority of the migration inflow to the NeoEuropes.
From 1947 - 1998, 29.6% of net settler migration to Australia were from the UK and the
Republic of Ireland (Price 1998, table 1); in Canada about 40% of post-war migrants have
been from that area.
Nonetheless despite the polyglot nature of recent immigration, primarily from third world
countries, the contemporary populations remain predominantly European-origin and English-
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speaking (Table 1), although the situation is changing rapidly (Day 1993, Kalbach et al 1993,
Dai and George 1996, Price 1999).
Table 1 Ancestry and Language characteristics, Neo-Europes late 1990s
Methods
Time-series of age-specific fertility rates by single year of age and where possible by marital
status and by ethnic origin or race were obtained by special request from the Australian
Bureau of Statistics, Statistics Canada, Statistics New Zealand, the US National Center for
Health Statistics and the Office for National Statistics, where these were not obtainable from
routine annual vital statistics publications. Data on birth rates inside and outside marriage for
Canada had to be specially prepared by Statistics Canada and were available for certain years
only, and it is stated that these marital status distributions need to be used with caution. Agespecific fertility rates by single year of age are available for the United States by race and (for
recent years) by Hispanic origin, but not by marital status, as the requisite marital status
distributions are lacking. Problems in the estimates for the Hispanic origin population and for
the white non-Hispanic population by single year of age at some ages make calculation of
accurate age-specific birth rates impossible for some years in the 1970s. Data for the United
Kingdom and the Irish Republic were obtained from the Eurostat New Cronos database up to
the year 1994, and data from England and Wales 1995 - 1999 by special request from the
Office for National Statistics. For some time-series purposes, data from England and Wales
must be used, rather than those from the United Kingdom. For example the total fertility rate
cannot be computed for the whole United Kingdom before 1961 because suitable data from
Northern Ireland are not available. The only series of data on births by true (biological) birth
order available for the UK are those reconstructed for England and Wales. Appropriate
acknowledgements were given below.
Model:
The Hadwiger function (Hadwiger, 1940, Gilje, 1972) may be expressed as
f ( x) ?
ab ? c ?
? ?
c ? x?
3/ 2
?
?c x
??
exp ? ? b 2 ? ? ? 2 ? ?
?x c
??
?
4
where x is the age of mother and a, b and c are three parameters to be estimated.
A two component mixture model of Hadwiger functions may be written as
? ab ?? c ?
f ( x) ? m?? 1 ??? 1 ?
? c1 ?? x ?
3/ 2
3/ 2
??
??
? ??
?c
? ab2 ?? c2 ?
? ??
x
x
2 ? c1
??? ? exp ? ? b2 2 ?? 2 ?
? 2 ?? ?
? 2 ?? ? ? ?1 ? m ???
exp ? ? b1 ?? ?
??
??
? ??
? x c2
? c2 ? ? x ?
? ??
? x c1
where x is the age of mother at birth. This model estimates six parameters. ‘m’is the mixture
parameter that determine the relative sizes of the two component distributions. ‘a’, ‘b1’, ‘c1 ‘
and ‘b2’, ‘c2’are the other parameters. These other parameters of the Hadwiger model can
also be interpreted demographically, as had been noted by other authors (Gilje1969, Yntema
1969) though denied by others (Hoem 1981). Thus the Hadwiger parameter a is highly
correlated with the Total Fertility Rate and the Hadwiger parameter c with the mean age of
the fertility schedule. In the mixture model with two c parameters, these were usually but
imperfectly related to the level and trend of the mean ages of the fertility schedules of births
outside and inside marriage. The modal age-specific fertility rate was confirmed to be
strongly correlated with the parameter ab/c (that is the modal rate, not the modal age) , as
mistakenly understood by Osona and Kohler, (2000); see Chandola et al (2000).
A general mixture model may be defined in a natural way by adding extra componetns with
corresponding parameters and, in particular, a three-parameter model was fitted to appropriate
population data in this study (Chandola et al; in preparation).
Goodness of fit was evaluated by examining the residual sums of squares and the asymptotic
standard errors for the parameter estimates that were derived during the maximum likelihood
estimation for these non-linear models. Where these standard errors were not small in relation
to the parameter estimates, the residual sums of squares and parameters for other mixture
models were examined and the best fits were chosen. In fact, the repeated fitting of models to
single years over long periods produced remarkably smooth and gradual changes in the
parameter values and their standard errors.
For some comparative purposes, the Irish Republic and England and Wales are included in the
Western European group. Where mean statistics are compared, unweighted means are
5
employed. Here we are interested in the average behaviour of national entities, not of the
average individual.
Results
The ‘English-speaking’ countries all show a number of common demographic features when
compared with the countries of ‘Western’ Europe, that is the 18 ‘western’ European countries.
Some of these distinct features are of long standing (Caldwell 1999, Szreter 1999)
Table 2 Selected fertility indicators of English-speaking and European countries around 1998.
Distinctive patterns are evident in the components of fertility. For example, in the late 1990s
in both groups of English-speaking countries the age-specific fertility rates at age 15 - 19 were
higher by a factor of two or three than the average of Western European counties (Table 2), a
contrast of long standing, being clearly apparent by 1950. The high rate for the United States
is particularly striking (51.1) although it has been declining since the early 1990s following a
campaign to reduce the incidence of teenage motherhood (Ventura et al. 1999). Teenage
fertility in England and Wales, never reached the high values of the NeoEuropes during that
period. However it has scarcely declined at all since the 1970s and is still at about 30 births
per 1000 women aged 15-19, the second highest among the countries we are considering.
Elsewhere in Western Europe, the asfr at ages 15-19 has fallen to very low levels, leaving the
rate in England and Wales four times the West European average and twice the level of any
individual Western European country. In the Irish Republic, childbearing traditionally has
started late. Accordingly asfr at ages 15-19 in the Irish Republic has not exceeded 23 per
1000 in the post-war years. However, the rate has not declined; by the end of the 1990s (19
per 1000 population aged 15-19) it had even risen slightly. Throughout most of the post-war
period and before, first marriage in the NeoEuropes occurred on average at least a year
younger than in Western Europe. Since the end of the 1970s all countries share increasing age
at first marriage and a lower level of marriage altogether, combined, in many countries, with
rising cohabitation.
It has not been possible to generate time series of mean age at first birth for the Neo-Europes,
and no vital statistics data at all are available from New Zealand on true (biological) birth
order, as these data are only collected for previous births in the same marriage. Mean age at
first birth was about 1 - 2 years younger than in continental Western Europe and, with the
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exception of Portugal and Austria, younger than that of any individual Western European
country. The low mean age at first birth in the United States (24.6) even in the 1990s is
particularly striking. Means for New Zealand are not available. The median value derived
from the Family and Fertility Survey shows that childbearing there begins at a youthful age:
26.2 for non-Maori women and 21.6 for Maori women aged 30-39 at interview; (Johnstone et
al 2001). Maori births are about 17% of the total.
At the end of the 1990s, the proportion of births outside marriage was about the same in the
two groups of English-speaking countries - about 1 in 3. This was higher than in Western or
Southern European countries but was lower than the Scandinavian average of about 1 in 2.
Despite their relatively high fertility, the English speaking countries also share relatively high
levels of childlessness compared with some continental countries (Table 2). In this respect, as
in some others, the NeoEuropes most closely resemble the Scandinavian countries. However
the relationship is not strong or consistent, as childlessness in New Zealand and Norway is
relatively low, and that in Switzerland and Germany is high. The very low fertility of the
Southern European countries, however, does appear to go together with lower levels of
childlessness.
The ethnic dimension.
It is sometimes suggested that the relatively high fertility, and other distinctive features of
birth rates in the New-Europes, are due not to any distinctive behaviour among their European
origin or English-speaking population. Instead it is claimed that these features arise either
through the high fertility and in some cases the high level of illegitimacy characteristic of the
numerous third world immigrant populations in some of these countries, or from indigenous
peoples with high birth rates. Ethnic minority fertility patterns are of considerable interest in
respect of the form of the fertility distribution, as will be shown later. But although the levels
of fertility among immigrant populations are often higher, the high level of overall fertility is
not primarily a minority effect, although in the US especially it is becoming more important
as those minorities grow in numbers. For example, the TFR for the whole United States in
1999 was 2.075 while that for white non-Hispanics alone was 1.85. The same calculation
cannot be made with such precision for New Zealand, but the non-Maori TFR in 1999
estimated by a residual calculation was 1.85 (Table 2). That includes contributions from
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Pacific Island and Asian populations (19% of the total). The former have a higher than
average total fertility rate, the latter group less so.
Nonetheless, 1.85 is about the same as the highest European figures in 1999 (Norway 1.84,
France 1.77 (1.9 in 2000), Ireland 1.88, Iceland 1.99). However, most of the bigger European
countries (France, but not Norway, Ireland and Iceland) themselves have substantial
immigrant minorities with higher birth rates. At least 10% of births in major European
countries are to women born abroad or of foreign nationality. More important, the higher birth
rates of immigrant and foreign women inflate the national totals. Thus in England and Wales
in 1996, where 13% of all births were to mothers born outside the UK, the overall TFR of
1.74 falls to 1.67 if the fertility of women born abroad is excluded (see ONS Birth Statistics
Series FM1 No 25, table 9.4). In the case of Germany the effect is more subdued: in 1996 the
national TFR of 1.31 would fall to 1.28 without the contribution of women of foreign
nationality (Bevölkerung und Erwerbstätigkeit 1998 R1 F1 table 1.3.7). Because of the
negligible numbers of ethnic minority population in the Republic of Ireland, this effect can be
ignored in that case.
In Australia in 1995 mothers born outside Australia, Europe and the English-speaking world
accounted for 12.6% of births (ABS 1989). Nonetheless total fertility rates of immigrant
women in the period 1987 - 91 were for the most part lower than the Australian average (then
1.8) (Abbasi-Shavazi 1998, table 1). The effect upon overall total fertility rate will clearly be
modest. In Canada, fertility differentials between Canadian-born and immigrant women are
minor. In the censuses of 1961 and 1971, and for the over-30s in 1981, immigrant family size
was less than that of the Canadian born. In 1991 it was slightly higher. Visible minorities in
Canada (essentially, those of non European origin) do have a higher birth-rate but it is
converging (Halli et al 1995).
To bring some of these statistics together, Figure 4 (ex-18) is a dendrogram of a hierarchical
cluster analysis of selected fertility characteristics (including the TFR, teenage ASFR, extra
marital birth rate and the Hadwiger mixture parameter to be discussed below) of European
and English speaking countries around the mid 1990’s. The resulting clusters put the United
Kingdom and Ireland with the English speaking countries overseas and these countries form a
cluster distinct from other European countries.
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Figure 4 Cluster analysis of English speaking countries fertility variables
Distributions of age-specific fertility rates by single year of age
Along with relatively higher TFRs, higher teenage ASFRs and lower mean ages at first birth,
the detailed age-specific profiles of Australia, Canada, New Zealand and the United States
also exhibit, to different degrees, a bulge in younger age fertility similar to that seen in the
England and Wales and Ireland (Figure 5, Figure 6). These distributions of the age-specific
fertility rates by single year of age are the particular subjects of this paper. The profile of the
UK is most closely matched in the distribution of fertility rates in New Zealand. A similar but
more modest distortion is evident in some years in Australia and Canada.
Figure 5 : Age-specific fertility rates by single year of age; England, Wales, Northern Ireland
and Scotland.
The United States, which up to the 1980s had a pattern not markedly different from the others,
had acquired a much more distinctive pattern by the 1990s. This is characterised by a very
steep rise in young age-specific fertility rates which peak around age 21, about 8 years earlier
than the modal value for the age-specific fertility rates of all the other countries in this
analysis. Overall, this distribution, with its very low modal age and flat-topped distribution
from age 21 to about age 29 is by far the most distinctive of any age-specific fertility rates
profile in the developed world. This may be an extreme form of a distribution distorted by
substantial young-age fertility.
Figure 6 Age-Specific Fertility Rates for English-Speaking countries by single year of age
. This characteristic feature of the ;bulge’ at ages 15-24 is not at all apparent to the naked eye
in the distributions for Australia and New Zealand in 1962, nor in the UK or Ireland before
about 1970. It is not striking visually in Australia or Canada until the 1980s (7 ex- 5). By the
1990s the bulge becomes most marked in New Zealand, prominent in Australia, less so in
Canada
Figure 7 ex-5a-d ASFR distributions in the period - 1960- 1980 for Australia, Canada, New
Zealand and the United States.
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This is least true, however, of the US pattern. This shows some distinctive features from the
earliest period for which we have data in appropriate form. The 1965 ASFR curve shows an
apparent excess fertility among the under-20s. This does not change over time in the same
way as in the other countries, but instead developed the characteristic flat-topped distribution
which becomes marked by the mid-1980s.
Modelling distorted patterns of age-specific fertility
These English speaking countries overseas display at least some features of the 'distorted' agespecific fertility rates typical of the UK and Ireland and relatively absent from Continental
countries. Therefore it seems reasonable to suppose that this reflects heterogeneity of fertility
behaviour which may require a mixture model to fit the fertility distributions, similar to that
required to fit the UK and Irish fertility distributions. This paper will test that hypothesis, as
well as examine some interpretations for any component mixtures found for the fertility
distributions.
In all the English speaking countries overseas, the (two component) mixture model fits the
actual ASFR distributions much better than the simple Hadwiger model in all recent years
(Figure 8 ex-7, which shows data for the mid-1990s). If we look at the US, in particular, the
simple Hadwiger model attempts to fit a relatively smooth fertility curve which is quite
inappropriate for the flat topped or plateau distribution of ASFRs. A two-mixture model fits
the observed distribution much better.
Figure 8a-d Simple and (two component) mixture models fitted to the ASFRs of New
Zealand, Australia, Canada and the United States- 1996-1998.
Furthermore, the mixture parameter ‘m’ indicating the magnitude of heterogeneity has been
increasing since the 1970s for all the four countries, with the US, in particular, having the
highest mixture parameter values out of all four countries (Figure 9), approaching one-half.
Figure 9 Trends in the Mixture parameter 1971- 1998
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Sources of heterogeneity
Illegitimacy
The previous analysis on England and Wales, and the Irish Republic, (Chandola et al 1999)
found a strong statistical association between the magnitude of the mixture parameter ‘m’(the
relative size of the minor compared with the major component) and the proportion of births
outside marriage (the illegitimacy ratio). The magnitude of the mixture parameter ‘m’
increased over time in parallel with the increase in the illegitimacy ratio. Given the rising
trend of the proportion of extra-marital births in all these overseas countries over this time
period (summarised in Figure 9), it seems reasonable to expect a strong association between
the mixture parameter and the proportion of extra marital births over this time period. That
assumes, of course that the distributions by age of mother of extra-marital and marital births
are different. This was indeed the case in these countries. Table 3 shows that the mean age of
the fertility schedule for non-marital births in the late 1990s in Australia, New Zealand and
the United States is in fact about five years younger than for marital births (using the same
denominator of total female population).
Figure 9. Trend in illegitimacy ratio, English-speaking countries.
Table 3. 5-year age specific fertility rates, marital and non-marital, Australia, New Zealand
and United States, late 1990s.
However the overall correlation between the proportion of extra- marital births and the
mixture parameter after 1971, taking all the four countries together, is only 0.6. This
relatively low value arises because of the different slope of the US regression line compared
to the slopes of Canada, Australia and New Zealand. If the variation of the illegitimacy ratio
is held to account for all the variation of the mixture component ‘m’ then the slope of the
linear functional relationship should be unity. This is approximately the case with the data for
Canada, Australia and New Zealand (Figure 10). But with the US data there is a departure
from this expectation. This discrepancy is caused by the high mixture parameter values at
relatively low rates of extra-marital births. Furthermore in the US case the relationship is not
linear.. For each country taken separately, the regression has a much better fit, in the case of
Australia, Canada and New Zealand with a slope of approximately 1 and r of 0.99, 0.85 and
0.96 respectively. The correlation in the US case is only 0.82 and is notably non-linear over
part of the distribution, and the slope is far from 1. While the difference between marital and
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non-marital births may account for some of the trends in the mixture parameter in the US
data, it is certainly not the only factor underlying the high mixture parameter values for that
country.
Figure 10 Correlation between the mixture parameter and the illegitimacy ratio, Australia,
New Zealand, Canada and US- 1971- 1998
The ethnic dimension
An important factor which may help to account for the marked heterogeneity in US fertility
patterns is the difference in fertility between different racial or ethnic groups, and in particular
the differences in the timing of births between those groups. In general, black and Hispanic
mothers begin childbearing earlier than do non-Hispanic Whites, and have much higher
proportions of births outside marriage.
On average, black mothers are the youngest group of all. Mean age of the fertility schedule in
1998 was 25.2 years for all black mothers, 24.9 for unmarried black mothers, and 22.8 years
for first births (95% of which are extra-marital). Unlike the Hispanic case, however, the
proportion of births to black women in the population has hardly changed in 20 years: there
were 610,000 in 1998 (15.5% of the total) and 568,000 in 1980 (15.7% of the total).
For example mean age of the fertility schedule for Hispanic mothers in 1998 was 25.96 years,
compared with 27.01 for white non-Hispanics marital fertility. The mean age at first birth is
23.1 years compared with 25.7 for non-Hispanic Whites. But while non-marital fertility
among non-Hispanic whites was, as expected, younger than overall ((mean 25.88 compared
with 27.01), this was surprisingly reversed among Hispanic mothers, where mean age for
unmarried mothers was 26.33 compared with 25.95 overall (Table 4). The proportion of
Hispanic births outside marriage (42% in 1999) has almost doubled since 1980 (23.6%); then
as now about twice the proportion among non-Hispanic whites (22% in 1998, Table 5).
The combined effects of these distinctions are not entirely straightforward to explore. Agespecific birth rates by single year of age are routinely available for each calendar year for
births to Black mothers and to White mothers, but not for births of Hispanic origin. It should
be possible to compute the Hispanic data by single year of age for the 1990s, using birth data
from the registration system and estimates of the population at risk from the annual Current
12
Population Survey. Difficulties with estimating the denominator have so far prevented that.
Further complications arise because the ‘Hispanic’ category is independent of the ‘racial’ one;
Hispanics can be of any race, although over 95% describe themselves as ‘white’. Hispanic
origin only began to be noted on birth certificates in 1978 and was not complete until 1989
(National Center for Health Statistics 1983, 1998).
The distribution of ‘white’ age-specific fertility rates is therefore made increasingly
heterogeneous not only by the growing level of illegitimacy in all components of the ‘white’
population, but by the substantial number of Hispanic births within the white group. This
proportion is growing rapidly. In 1999, 786,051 (25.1%) of the 3,132,501 ‘white’ births were
to Hispanic mothers, compared with an estimated 338,000 (11.5% of the white total) in 1980.
(National Center for Health Statistics 2001, e.g. table 7).
Table 4 Mean age of Fertility Schedule
These contrasts are shown graphically in Figure 11a.
Figure 11 a Age-specific fertility rates by race, Hispanic origin and marital status, US 1998
Single-year age-specific rates are not available for births outside and inside marriage within
these major racial and ethnic groups in the US. Therefore it is impossible at present to
apportion directly the contribution to the ‘distortion’ effect in the US fertility profile arising
separately from the two factors of race/ethnicity and illegitimacy.. However, the Hadwiger
mixture models by themselves can at least give us some idea of the magnitude of the fertility
heterogeneity within the US population as a whole , and also separately within the black and
white populations (Figure 12).
Table 5 births outside marriage
In the black population, the young-age fertility group estimated by the model is actually larger
than the later-age group, the only such example in this study. The ‘m’parameter estimated for
1996 is 0.53, substantially less than the proportion of births outside marriage, which in 1996
was 0.70. In 1974 these figures were 0.23 and 0.47 respectively. If we take the c1 and c2
parameters to be estimates of the mean age of motherhood of young-age and later-age
13
mothers respectively, then the mean ages in 1996 were separated by a decade; 20.9 years and
30.7. In fact, as noted above, the mean age of unmarried black mothers was 24.9, while the
mean age of married black mothers was XX (still to be calculated- data not available) A high
proportion of black mothers are teenagers, almost all (95%) unmarried. In 1999 20.7 % of
black mothers were to teenagers, compared with 10.9% of white mothers).
The trend of the black ‘m’ parameter is more regular than that of the US population as a
whole. Its correlation with the black illegitimacy ratio is 0.92, somewhat higher than for the
US population as a whole (0.83). Expressed as decimal fractions, the ‘m’parameter has kept
between 0.10 and 0.25 below the illegitimacy ratio over the period. Extra-marital fertility is
likely to be a major indicator of heterogeneity in black fertility, as the population is relatively
ethnically homogeneous.
For the white population, the Hadwiger modelling procedure resolves the fertility rate
distribution for 1997 into two substantial components with a mixture parameter value of 0.43
(Figure 12). This is considerably higher than the illegitimacy ratio of 0.26 in that year.
However at the beginning of the period for which estimates are possible (1974), the value of
the m parameter (0.07) is nearly identical with that of the proportion illegitimate (0.065).
While the trend in the illegitimacy ratio is nearly linear; that of the ‘m’parameter, as with US
fertility as a whole, is irregular, increasing rapidly to 0.35 by the mid-1980s with no further
increase until the early 1990s. Accordingly r is only 0.80. In 1997 the parameters c1 and c2,
model estimators of mean age of childbearing, are 21.9 and 30.6 for the smaller and larger
components respectively, not greatly different from the estimate for black mothers.. This
compares with the actual mean age at maternity of 26.0 and XX respectively in the nonmarried and married distributions of mother in that year.
However, the white population clearly has at least two major sources of heterogeneity, the
Hispanic / non Hispanic division and the marital /non marital division. As noted above, in the
Hispanic population births outside marriage are much more numerous (42.1% in 1999) than
among the non-Hispanic population (22.0%), and mothers are generally younger.
Figure 12 Hadwiger mixture models US white and black populations
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Ideally the Hispanic and non-Hispanic white fertility rate distributions would next be
modelled separately. That might permit the peculiarities of the distribution to be partitioned
between the effects of ethnic group and of illegitimacy. In default, the estimation from a two
component mixture model provides a set of parameters for each component together with a
mixture parameter. These components provide the basis for an hypothesis which can be tested
against real data when it becomes available.
It seems likely that differences between the characteristics of marital and non-marital births,
and those of different ethnic groups, could contribute independently to the timing and
volume of fertility. Jointly, they might account for the high mixture parameter values for the
US and the distinctive plateau in the all – US asfrs for women at ages 21 to 29. Until the
limitations of data are rectified, all we can do is to see what measurable components of white
fertility have the best correlations with the mixture value ‘m’. None of the possible trends can
account for the irregularities of the ‘m’parameter in the early 1980s. The proportion of
Hispanic births outside marriage is, however, similar in magnitude. The trend of the overall
illegitimacy ratio in the white population rises at a less striking pace but is highly correlated
(r=0.98) with the proportion of white births which are Hispanic – both these variables nearly
quadruple in magnitude over the period in question. Statistical treatment must be very
elementary and tentative because of the sparse and incomplete nature of the data. Simple
regression on the white ‘m’parameter suggests that the overall white illegitimacy ratio is the
most important component (r2 =0.65 compared with r2=0.33 for the proportion of white
births which are Hispanic. However a stepwise regression (n=15, p=0.014 , r2 0.38) shows
that the proportion of births which are Hispanic emerges as the only significant independent
variable (standardised coefficient 0.62).
New Zealand – the Maori dimension
The correlation between the trend in overall ‘m’parameter and the illegitimacy ratio in New
Zealand 1971 –1998 was high: 0.96. Statistically, any ethnic effects would appear to be
embraced by the contribution to illegitimacy. At first sight this seems surprising; there are
substantial differences in the timing and volume of births between ethnic groups in New
Zealand between Maori and non-Maori populations (the residual ‘non-Maori ‘population is
not entirely of European origin but includes a proportion of Asian, Pacific Island and other
origins) (Figure 13b). Maori mothers have their first birth considerably earlier than the rest of
the New Zealand population, by about 5 years (Johnstone et al 2001); a young-age pattern
15
which has changed little in many years. In the 1980s, Maori teenage fertility rates were
surpassed only by those of US blacks in the populations being considered here (94 births per
1000 teenagers in 1980, and 70 in 1999). Furthermore, Maori women have much shorter
intervals to their second birth than non-Maori women. .Hence the Maori age-specific fertility
curve is skewed strongly to the left, not unlike that of the US Blacks and Hispanics. The nonMaori age-specific fertility curve is more symmetrical, with a much older modal age, but
shows an impressive bulge at young age-groups (Figure 13b).
Births outside marriage have always been common among the Maori population but no
routine statistics are published, partly because of many Maori partnerships are legitimised by
community rather than registration. However, the New Zealand FFS showed that non-Maori
women born in 1956-75 were twice as likely as Maori women to be married when their first
child was born. About 33% of first births of non-Maori women born 1966-75 were outside
any partnership and another 23% were in cohabiting unions. Among Maori women these
proportions were 52% and 36% respectively (Johnstone et al. 2001, table 15M p78). The
Maori asfr for 1997 yields two Hadwiger mixture components where ‘m’ is 0.29 and c1 and
c2 19 and 28 respectively. Although we lack detailed data, the ‘m’value seems too low to be
a good match for the proportion of Maori births outside marriage. However as noted above,
the Maoris are a ‘naturally’ early-fertility population and given the customary nature of
marriage it is not clear what sub-group, if any, the ‘m’ parameter might be pointing to. On a
constant ethnic definition, Maori births have comprised the same proportion of total births in
New Zealand for twenty years: 12.0% in 1976 and 12.5% in 1995. Their fertility patterns have
therefore not grown as a contribution to the total of births over that time, unlike the case of the
Hispanics in the US.
The ageing fertility pattern of the European-origin population in New Zealand has grown
away from the more slowly changing Maori age-distribution of births. Average age of Maori
mothers was 24.1 in 1975 and 26.5 in 1999. That of the whole population increased from 25.4
to 29.2 in the same period (including Maori – data for European origin alone are not
available). However inter-racial unions are common. Many New Zealanders have part-Maori
origins; many Maoris have European ancestors. Defining when a Maori is a Maori is a very
uncertain art (Pool 1991). A new ethnicity question on the birth registration form provoked an
‘increase’ of Maori births (defined on the basis of the child’s ethnicity) from 12.5% of all
births in 1995 to 27.6% in 1996 (28.1% in 1999; data from Statistics New Zealand 2001).
That ‘increase’ in births in turn provoked an ‘increase’ in the Maori TFR from 2.19 in 1990
16
(national average 2.18) to 2.60 in 1996 (national average 2.00) without any suggestion that the
reproductive behaviour of actual individuals had changed correspondingly.
Births outside marriage have clearly increased across the board in New Zealand , although the
increases of cohabitation and births outside marriage among the population of European
origin have been the more striking, probably the highest among any of the European-origin
populations we care considering. This switch in behaviour in formerly ‘prim’ New Zealand to
the substitution of marriage by cohabitation was allegedly sparked by new welfare reforms in
the 1970s which removed welfare advantages in favour of married couples (Pool 1991,
Jackson and Pool 1994, Lapierre-Adamcyk et al 1997).
Figure 13a and 13b ASFRs by ethnic groupings- US and New Zealand 1998
Australia and Canada
These ‘ethnic’ effects do not seem to be important in Canada or in Australia. There, the ethnic
dimension in fertility, despite high immigration, is more subdued because of the origins and
fertility patterns of the more numerically important ethnic groups. Levels of illegitimacy; both
281per 1000 live births in Australia and in Canada in 1997, are more modest than in New
Zealand and about the same as among US non-Hispanic whites. In Australia, the correlation
of the trend of the illegitimacy ratio with the m parameter is very high - 0.99. Young-age
distortions in the age-distribution of fertility are, however, relatively modest. In Australia nonmarital childbirth is no longer primarily the ‘unplanned experience of women in their teens
and early twenties but more typically… involves consensually partnered women of normative
reproductive age’ (Carmichael, 1995). In Australia as noted above, the indigenous population
is relatively small and the nature of immigration means that even in 1999, 88% of the
Australian population claim European ancestry. Aggregate fertility differences between
Australian natives and immigrants are slight.
We believe that the much lower correlation of 0.85 in Canada is due, at least in part, to the illdefined nature of illegitimacy ratios in Canada in some years and the discontinuity in timeseries. ‘Visible minorities’ in Canada in 1996, as noted above, comprise 11% of the
population, with another 3% in aboriginal groups. The aggregate birth rates of the former are
little different from the population average (Ram and George 1990, 1993, Balakrishnan et al
1993, Beaujot and Matthews 2000). This is also now true of the French Canadian population,
by far the biggest minority in Canada, geographically concentrated in Quebec. There,
17
aggregate fertility, once significantly higher than the Canadian average, fell to below average
after the 1960s. In 1997, TFR in Quebec was 1.52 compared with 1.56 in the rest of Canada.
Its pattern is somewhat different, however; cohabitation and illegitimacy are higher than in
English-speaking Canada, recalling the patterns observed in New Zealand. The illegitimacy
ratio in Quebec in 1996 was 523 compared with 283 in all Canada (Lapierre-Adamcyk et al
1997).
Discussion
The aim of this paper was a simple empirical one; to determine whether elements of a
common fertility pattern existed in the English-speaking world, especially in respect of the
age-profile of fertility. Some evidence seems to exist for this proposition, including an
increase in the heterogeneity of reproductive behaviour through the rise of a distinctive earlyage component in fertility since the 1970s.
The existence of high to very high levels of correlation between the increase of the mixture
parameter and the rise of births outside marriage (with the partial exception of the United
States), while in no way demonstrating any causal connection, at least is in the expected
direction. We saw that the statistical relationship in the United States is somewhat improved
when the major racial and ethnic groups within the US population are considered separately.
However the marked departures from linear trend in the US mixture parameter still require
further explanation.
Not too much should be expected from a simple model when applied to the nuances and
complexities of human behaviour. While the magnitude of the mixture parameter m tends to
bear a constant relation to the rise of the illegitimate component of births in these populations,
the identification by the model of two distinct populations is of course a gross simplification.
For example the c parameter in the simple models corresponds closely to the actual observed
mean age of the fertility schedule. But the two sub-populations specified by the mixture
model are necessarily abstractions. The c2 parameter would be expected to represent the mean
age of the fertility schedule of the later-age (mainline) fertility component. In fact, it is
actually quite close to the observed mean age of the fertility schedule in developed societies
(it is about 30 in all cases). That may be considered to be the modern norm. However the c1
parameter, corresponding to the mean age of the fertility schedule of the younger age
18
component, does not vary very much (between 19 and 21) and is 2 - 5 years younger than the
mean age at maternity of the sub-populations for which we have real data (Table 3).
Of course, the world is not that simple. Unmarried mothers do not all have their babies young,
nor do all married ones all wait for a normative age. In particular, the popularity of various
kinds of informal cohabitation blurs any statistical distinction between married and
unmarried. Formally unmarried, cohabiting mothers may be behaving exactly like married
mothers, with late childbearing, and may remain cohabiting throughout their reproductive
lives. Others may be in no partnership, just left holding the baby. On average, cohabiting
mothers tend to be younger than married ones, partly because of a social class difference and
partly because in many cases cohabitation is a preliminary to marriage and therefore precedes
it. The extent to which cohabitation replaces marriage varies greatly between societies and
over time (Kiernan 1999); illegitimacy as a status has been formally ‘abolished’ in most
Western countries (in the UK in 1987, for example, Lewis and Kiernan 1996). However
bureaucratic gestures have not abolished non-cohabiting unmarried motherhood, where the
social and demographic characteristics are distinctive and often unfavourable: the youth of the
mothers, their low level of education, location in public housing and dependency on welfare,
often with a similar family background (Kiernan and Diamond 1982) in a ‘cycle of
deprivation’ (Rutter and Madge, 1976).
Possibilities for adverse comments on the growth of unmarried motherhood and the
persistence of youthful childbearing in a world of older mothers have not passed un-noticed.
Pool et al. (1999, p 156) note with disapproval that the ‘reproductive profligacy of the “less
worthy” has attracted criticism from ‘neo-liberal’ sources in New Zealand and in the United
States. Prominent among them is Charles Murray (1983, 1990), whose identification of a
growing welfare dependant underclass in the US and the UK, characterised by
unemployment, welfare dependency, youthful childbearing and high rates of births outside
marriage has been highly controversial. Controversy aside, the existence of a youthful fertility
group (specifically teenage mothers, in US and UK almost all unmarried) is officially
recognised as a public problem. The only fertility-related population policy in the US and in
the UK is the attempt in the 1990s to reduce teenage fertility to specified lower targets, with
some success in the US (Ventura et al. 1999, National Center for Health Statistics 2000).
19
There is no doubt that in respect of sexual matters, living arrangements, marriage, divorce,
childbearing outside marriage, the English speaking world has shared the revolutionary
experiences in morals, mores and demographic response typical of Western developed
populations in general since the 1970s (Lesthaeghe 1995). In this broader context, the rise of
births outside marriage and all the rest in the countries we are studying is no great surprise.
It is more interesting to ask if the English speaking countries have participated in this ‘second
demographic transition’ in any kind of distinctive way. This empirical paper can only mention
briefly this or any other possible causal mechanisms. Nonetheless the sexual cultures of the
countries of the English speaking world may have features in common, which has provoked
behaviour to veer from one extreme to its opposite. Sexual culture, like other aspects of
culture, can persist in recognisable form despite adaptation to social and economic change. In
the first demographic transition, couples in Britain delayed marriage and abstained from sex
within and without marriage to a marked degree, a reflection of long-standing British
anxieties and embarrassed fumblings about sexual relations not shared on the Continent
(Szreter 1996).
Here the important thing is the extent to which this sexual demography is shared with the rest
of the English –speaking world. This appears to have been so in Australia and New Zealand at
least in the earlier part of the 20th century ((Jones, 1971; McDonald 1975). The United States,
with its more mixed European heritage, may have taken a different path, although Caldwell
(1999) documents many examples of common attitudes of embarrassment. Yet despite the
exceptional level of divorce in the US in the 20th century, earlier levels of births outside
marriage, for example were very low throughout all the countries under consideration
compared with continental Europe. The late onset of demographic transition in the United
States, Australia and Britain, despite their economic advantage, is laid at the door of problems
with the acceptance of sexuality and contraception in the English-speaking world (Caldwell
1999). Now of course, all these countries are characterised by high levels of divorce, high
levels of unmarried parenthood and of teenage childbearing compared with the rest of the
Western World, as if emerging from tight control into a suddenly normless world.
All commentators seem agreed , however, that the relatively high fertility of the countries
concerned in recent decades has nothing to do with low levels of modern contraceptive use.
On the contrary, a pattern of high levels of pill use in youth followed by high levels of
20
contraceptive sterilisation and more recent recourse to the condom characterises all the
countries concerned, a further example of similarity when compared with other modern
populations (Pool et al 1999, Balakrishnan et al (1993), Lucas and Fisher (1998) , Piccino and
Mosher 1998) . What needs to be explained is the low use of contraception and abortion in
particular groups of younger people, in marked contrast to the behaviour of young people in
western Europe where equally enthusiastic sexual activity does not have the same dire
reproductive consequences.
There is of course noting unusual about the transmission of values with migrants and their
preservation in new lands, although some of the claims for the transmission of British
folkways to the United States maybe excessive (Fischer 1989). A proper exploration of the
similarities in history, culture, values, institutions in the English Speaking world overseas,
however, is clearly beyond the scope of this paper (see Inglehart 1990, Inkeles 1997, and
other analyses of the World Values Survey). All this paper set out to do was to document
some empirical similarities.
Conclusions
There does seem to be a statistically distinctive set of demographic attributes common to the
English speaking populations which make them to stand out as a group in conventional
statistical analysis when compared with the other countries of the Western World. The four
English-speaking countries abroad share these features to a greater extent than the two
European members of the group. However in aggregate fertility terms, a degree of divergence
has become apparent in the last decade between Australia and Canada on the one hand and the
United States and New Zealand on the other.
This general demographic similarity is apparent in the historical trend of various fertility
indicators during most of the 20th century; for example in respect of relatively youthful
fertility, high fertility, substantial and protracted baby booms, and initially low illegitimacy
followed after the 1970s by very high illegitimacy. Insofar as this is so it is not surprising in
view of the shared language, population origins, and similarities of legal, administrative
political and welfare systems in the countries concerned.
21
Some of these features are captured by the Hadwiger modelling, which identifies and
quantifies excess early childbearing compared with the more regular pattern observed in the
left hand side of the distribution in earlier periods (that is, before about 1970) and in other,
European countries described earlier (Chandola et al (1999). The simple correlation of the
Hadwiger mixture parameter m with the level of births outside marriage is good or very good
in the countries considered except for the United States. There, insofar as racial and ethnic
diversity can account to some extent for the less good fit, insofar as it can be taken into
account in suitable statistical fashion. The identification of the c parameters with the mean age
of maternity of the dub-groups identified is less easy to demonstrate, and it is important to
remember the diversity of forms of cohabitation and of the circumstances of childbearing
outside marriage in the countries concerned.
This English-speaking distinctiveness is likely to change over time as these populations,
including the UK, become less Anglo - Celtic in character as a result of continued high
immigration and / or the higher fertility of some immigrant and indigenous groups, their
effects amplified by the ‘multi-cultural’ policies the adoption of which seem to be another
distinctive characteristic of the English-speaking world compared with Western Europe.
In the case of the US white population, the growing Hispanic dimension seems exceptionally
important in generating an exceptional profile of fertility. In the population overall, the high
and growing proportion of births to black and Hispanic mothers, in combination with their
high levels of youthful illegitimacy, generates the unique US age-specific fertility profile.
Acknowledgements
Grateful acknowledgement is made for advice, data or figures to Ms Stephanie Ventura, Ms
Irene Tang, Ms Doreen Duchesne, M Alain Bélanger, Dr Roderick Beaujot, Dr Bali Ram, Mr
Chris Shaw and others. Errors remain the responsibility of the authors alone.
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26
Tables
Table 1 Ancestry and Language in the English-Speaking World
Ancestry
Country
Australia 1986
Language
Percent English Irish
Ancestr ,
y
Welsh.
Scottis
h
Epony Scottish other
mous
British
British Next
/
ranked
Irish
origin
18.6 43.3 2.4 2.3 Italian 3.3
n/a
57.8 12.1 n/a German 3.5
85.7 Italian 2.9
Ancestry
Ethnic
Strength'
85.0 Italian 2.3
Australia 1996
Canada 1996
speaking Next
English ranked
at home language
30.9 40.1 13.2
French 19.6
59.2
1986 Census
Price 1999 t. 1
1996 Census
Ethnic
origin
1996 Census
Ethnic
group
1991 Census
Euro
pean
New Zealand
1991
New Zealand
1996
US 1990
US 1979
79.5
Maori 12.9
71.7
Maori 14.5
91.1 Maori 4.23
1996 Census
German
18.3
German
28.8
86.2 Spanish 7.5 Ancestry
1990 Census
87.8
1979 CPS
5.2 12.6
9.1
31.6 24.4
Ancestry
Sources:
Australian Bureau of Statistics 1991 Multicultural Australia table 2.1, 4.1 (from 1986
Census)
Australian Bureau of Statistics 2001 1996 Census
Price 1999 t. 1.
Census of Canada 1996
Dept of Statistics, New Zealand 1993 New Zealand's Multicultural Society t 1
US Dept of Commerce Ancestry of the Population of the United States 1990 CP-3-2 table 1
US Dept of Commerce (1982) Current Population Report Series P-23 No 116
Ancestry and Language in the United States November 1979
Note: in the 1990 US Census, 84.7 million people are categorised as 'other and not reported'
in respect of responses to the 'ancestry' question'
Percentages are based on total population of 248 million. In the CPS, percentages are based
on total responding.
In the 1996 New Zealand Census, different definitions of 'ancestry can give 71.7% as only
European ancestry but if some European ancestry is included, the total rises to 79.6%
27
Table 2 Basic Fertility Characteristics of the English-Speaking countries compared with
selected European examples, 1998 or nearest
Country
TFR
asfr asfr mean age % first
CFS Illegiti- % childless
15-19 35-39 at first
births
macy age 45
1955
birth
ratio 1955 cohort
cohort
21.0 43.0
26.9
44.1
2.26
287
22.3 32.6
26.8
297
29.6 48.5
2.75
425
11.1
51.1 37.4
25.0
40.0
328
16.5
31.0 40.4
26.2
42.0
2.51
334
Australia
Canada
New Zealand
United States
unweighted
mean
1.78
1.62
1.91
2.06
1.84
United Kingdom
Irish Republic
unweighted
mean
1.72
1.93
1.83
31.0
18.6
24.8
40.0
69.6
54.8
26.7
27.1
26.9
40.1
Denmark
Finland
Norway
Sweden
unweighted
mean
1.72
1.70
1.81
1.51
1.69
7.8
9.4
12.0
7.2
9.1
40.6
40.4
43.0
38.0
40.5
Austria
Belgium
France
Germany
Netherlands
Switzerland
unweighted
mean
1.34
1.55
1.75
1.36
1.63
1.46
1.52
14.4
9.1
9.4
12.8
5.0
5.4
9.4
Greece
Italy
Portugal
Spain
unweighted
mean
1.30
1.19
1.46
1.17
1.28
11.0
9.0
21.0
7.6
12.2
40.1
1.95
2.68
2.32
376
283
329
15.0
14.0
14.5
27.5
27.8
27.2
27.4
27.5
46.2
40.0
41.7
41.0
42.2
1.85
1.91
2.05
1.90
1.93
448
372
490
541
463
13.0
18.0
11.0
13.0
13.8
23.4
24.0
37.8
26.6
51.0
36.0
33.1
26.0
n/a
n/a
n/a
29.1
n/a
27.6
44.8
n/a
n/a
n/a
41.1
n/a
43.0
1.76
1.82
2.12
1.62
1.87
1.72
1.82
295
149
400
180
208
87
220
25.6
32.3
29.0
33.0
30.0
26.8
28.4
26.1
28.5
27.5
46.7
49.7
52.4
49.7
49.6
1.83
1.83
2.00
1.91
1.89
37
90
201
117
111
10.0
8.0
22.0
17.0
11.0
8.0
10.0
Notes:
n/a: not available. birth order data only from births in marriage or current marriage
Sources: Council of Europe, National Demographic Publications
Eurostat (proportion childless)
28
29
Table 3
Age-specific fertility rates, marital and non-marital
nb age-specific fertility rates are calculated from the same denominator of
total population
New Zealand 1998, total resident population, all ages
female
births
population
marital
non-marital asfr (m) asfr (nm)
15-19
131410
236
3654
0.0018
0.0278
20-24
130460
2821
7044
0.0216
0.0540
25-29
143320
9823
6118
0.0685
0.0427
30-34
150050
12118
3968
0.0808
0.0264
35-39
159020
5487
1997
0.0345
0.0126
40-44
142150
823
356
0.0058
0.0025
45-49
126430
31
21
0.0002
0.0002
15-49
982840
31339
23158
1.0663
0.8308
mean age of fertility schedule
30.85
26.00
source: NZ Demographic Trends 1999 t 1.6, 2.5
Australia 1995, total resident population, all ages
15-19
617045
1304
11243
20-24
708717
23859
22951
25-29
687387
66208
16286
30-34
730377
65429
10752
35-39
709221
24668
4917
40-44
663996
3731
990
45-49
619246
120
41
15-49
4735989
185319
67180
Mean age of fertility schedule
0.0021
0.0337
0.0963
0.0896
0.0348
0.0056
0.0002
1.3114
30.15
0.0182
0.0324
0.0237
0.0147
0.0069
0.0015
0.0001
0.4875
25.68
Source: Births Australia 1995 t 12, appendix B
United States 1997, all races
10 to 14
9283112
436
9685
0.0000
0.0010
15-19
9241412
107103
376117
0.0126
0.0441
20-24
8532461
503416
438632
0.0536
0.0467
25-29
9398632
834674
234762
0.0803
0.0226
30-34
10400509
761967
124831
0.0672
0.0110
35-39
11338341
349840
59870
0.0325
0.0056
40-44
10776762
65870
13547
0.0070
0.0014
15-49
78367280 2622870
1247759
1.2652
0.6566
Mean age of fertility schedule
28.97
23.47
Note 3333 births to women over age 45 included in 40-44 age group
There are no data on non-marital births to women 45-49.
Source: National Vital Statistics Reports Births: Final Data for 1997 tables 2,
17, App table II
30
Table 4
Table 4 Mean age of Fertility Schedule by Race, Hispanic origin and birth-order, US 1998
White
White non-Hi
Hispanic (all)
Black
All births
27.02
27.01
25.95
25.24
First births
25.13
25.66
23.13
22.84
Extra-marital
25.98
25.88
26.33
24.94
Source: Births: Final data for 1998. National Vital Statistics Reports Volume 48 no 3
31
Table 5 Trend of US illegitimacy ratios and m parameter by race, Hispanic origin and age
1940 - 1999
Illegitimacy ratio, all ages of
Illegitimacy ratio for mothers 15
mother
- 19
All
Year
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
1979
1978
1977
1976
1975
1974
1973
1972
1971
1970
1965
1960
1955
1950
1945
1940
All Whit Whit Whit
e
ee
m
non- m
param all Hisp param
eter
anic eter
33.0
26.8 22.1
32.8
26.3 21.9
32.4 0.49 25.8 21.5 0.43
32.4 0.47 25.7 21.5 0.41
32.2 0.46 25.3 21.2 0.39
32.6 0.44 25.4 20.8 0.36
31.0 0.43 23.6 19.5 0.34
30.1 0.42 22.6 18.5 0.32
29.5 0.42 21.8 18.0 0.33
28.0 0.44 20.4 16.9 0.35
27.1 0.45 19.2
0.37
25.7 0.46 17.7
0.36
24.5 0.44 16.7
0.37
23.4 0.41 15.7
0.35
22.0 0.40 14.5
0.35
21.0 0.41 13.4
0.38
20.3 0.40 12.8
0.35
19.4 0.41 12.1
0.33
18.9 0.38 11.6
0.30
18.4 0.35 11.0
0.25
17.1 0.28 9.4
0.21
16.3 0.22 8.7
0.19
15.5 0.20 8.2
0.15
14.8 0.14 7.7
0.13
14.3 0.11 7.3
0.09
13.2 0.11 6.5
0.07
13.0 0.11 6.4
12.4 0.11 6.0
11.3 0.17 5.6
10.7 0.26 5.7
7.7 0.30 4.0
5.3
2.3
4.5
1.9
4.0
1.8
4.3
2.4
3.8
2.0
Blac Blac Blac Hisp All Whit Whit
k
kk
anic
e
e
non- m
nonall Hisp param all races
all Hisp
anic eter
anic
68.9 69.1
42.2 78.7 72.6 72.6
69.1 69.3
41.6 78.5 72.2 71.9
69.2 69.4 0.53 40.9 77.8 71.1 70.9
69.8 70.0 0.53 40.7 75.9 68.7 69.3
69.9
0.52 40.8 75.2 67.7 67.9
70.4
0.50 43.1 75.5 67.6 66.6
68.7 68.9 0.52 40.0 71.3 62.3 62.3
68.1
0.52 39.1 70.0 60.4 59.7
67.9
0.52 38.5 68.8 58.8 57.8
66.5
0.55 36.7 67.1 56.4 55.5
65.7
0.53
66.6 55.3
64.7
0.54
65.3 53.7
63.4
0.52
63.4 51.4
62.4
0.49
60.8 48.3
61.2
0.47
58.0 44.8
60.3
0.47
55.6 41.7
59.2
0.47
53.4 39.3
57.7
0.47
50.7 36.7
56.9
0.45
49.2 35.0
56.1
0.46
47.6 33.1
54.7
0.41
46.1 30.3
53.2
0.36
44.1 28.6
51.7
0.33
42.9 27.3
50.3
0.31
40.3 24.8
48.8
0.27
38.2 22.9
47.1
0.24
35.4 20.2
45.8
33.9 19.1
43.9
32.8 18.1
40.5
30.9 17.0
37.6
29.5 17.1
26.3
20.8 11.4
21.6
14.8 7.2
20.2
14.2 6.4
18.0
13.4 6.2
17.9
16.8
13.5 7.0
Blac Blac Hisp
k
k anic
nonall Hisp all
anic races
95.5 95.6 72.9
95.7 95.8 72.9
95.7 95.8 71.6
95.4 95.5 67.7
95.2
67.3
95.3
69.7
92.9 93.1 62.8
92.6
61.9
92.3
61.2
92.0
59.4
92.1
92.0
91.4
90.7
90.2
89.6
89.0
87.5
86.7
86.7
85.1
82.9
82.0
79.7
76.9
73.7
71.0
69.6
66.9
62.7
58.7
Source:National Center for Health Statistics National Vital Statistics
Reports
32
Births: Final Data for 1996, 97,98, 99,
table 17
US all races m parameter from Bob Hiorns run of 15
November 1999
(for 1940 - 1975 up to 1960 black and
other)
National Center for Health Statistics 2000 National Vital Statistics Reports Volume
48 No 16
Nonmarital Childbearing 'in the United States 1940 - 99(revised)
Table 4
National Center for Health Statistics 1999 Vital Statistics of the United States 1993
Volume 1 Natality Table 1-76 p 199 Washington DC USGPO
Note 'all other', not ‘black’, until 1969. Estimated race of child up to 1979. Race of mother from
1980
33