3238.0 - Estimates and Projections, Aboriginal and Torres Strait Islander Australians, 2001 to 2026 Quality Declaration 
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Contents >> Assumptions >> Fertility assumptions

FERTILITY ASSUMPTIONS

Three main assumptions have been made for future fertility rates of Aboriginal and Torres Strait Islander women:

  • constant fertility rates;
  • an annual decline of 0.5% in fertility rates; and
  • an annual decline of 1.0% in fertility rates.

These assumptions were primarily chosen on the basis of the declining trend in fertility as indicated by data from the 'children ever born' question asked in the Census.

The same rate of decline in fertility rates has been assumed for each state and territory, Indigenous Region, and Remoteness Area; that is, each geographic area is assumed to experience a 0.5% annual decline in fertility rates over the projection period for Series B.

The effect of alternative fertility assumptions on the number of projected births and size of the future Aboriginal and Torres Strait Islander population is described in Chapter 4.


Trends in fertility rates

Children Ever Born

Cohort fertility rates, based on the 'children ever born' question asked in the Census of Population and Housing, illustrate a decline in Aboriginal and Torres Strait Islander fertility over time.

The number of children ever born provides information on actual fertility outcomes of women of different ages. In particular, the number of children ever born to women aged 40-44 years can be regarded as a measure of completed fertility; that is, on average how many children this group of women each had throughout their entire reproductive lifetimes.

In the 1981 Census, Aboriginal and Torres Strait Islander women aged 40-44 years (born in 1937-1941) had an average of 4.55 babies per woman. In comparison, Aboriginal and Torres Strait Islander women aged 40-44 years at the time of the 1986 Census (born in 1942-1946) had an average of 3.97 babies per woman. Those aged 40-44 years at the time of the 1996 Census (born 1952-1956) had an average of 3.10 babies per woman, and Aboriginal and Torres Strait Islander women in this age group at the time of the 2006 Census (born in 1962-1966) had fewer children (2.84 babies per woman). The 2011 Census showed that Aboriginal and Torres Strait Islander women in this age group (born in 1967-1971) had even fewer children (2.63 babies per woman).

As indicated in graph 2.5, the average number of children ever born to Aboriginal and Torres Strait Islander women has been declining for each age group over the past three decades. These declines, particularly in the younger age groups, indicate probable declines in the future overall level of Aboriginal and Torres Strait Islander fertility.

In the 1981 Census, Aboriginal and Torres Strait Islander women aged 25-29 years (born in 1952-1956) had an average of 2.58 children ever born. In comparison, Aboriginal and Torres Strait Islander women aged 25-29 years at the time of the 1986 Census (born in 1957-1961) had an average of 2.20 babies per woman. Those aged 25-29 years at the time of the 1996 Census (born in 1967-1971) had an average of 1.88 babies per woman, and Aboriginal and Torres Strait Islander women in this age group at the time of the 2006 Census (born in 1977-1981) had an average of 1.73 babies per woman. In 2011, women in this age group (born in 1982-1986) had an average of 1.49 babies per woman.

2.5 Average number of children ever born(a)(b), Aboriginal and Torres Strait Islander women - 1981, 1986, 1996, 2006 and 2011 Censuses
Graph: 2.5 Average number of children ever born(a)(b), Aboriginal and Torres Strait Islander women—1981, 1986, 1996, 2006 and 2011 Censuses


Total Fertility Rate

The total fertility rate (TFR), based on birth registrations, represents the average number of children a woman could expect to bear during her lifetime if she experienced current age-specific fertility rates at each age of her reproductive life.

In the early 1960s, based on Census data, the TFR for Aboriginal and Torres Strait Islander women was 5.8 babies per woman. Since then, fertility levels for Aboriginal and Torres Strait Islander women have declined substantially, with the largest decreases being recorded during the 1970s. Fertility of Aboriginal and Torres Strait Islander women declined to a low of 2.0 babies per woman in 1996, gradually increased to 2.8 in 2010, before slowly decreasing over the last few years.

Graph 2.6 presents TFRs for Aboriginal and Torres Strait Islander and all women for the period 1961-1966 to 2012. Due to the limited availability and variable quality of historical Aboriginal and Torres Strait Islander birth registration data, fertility rates of Aboriginal and Torres Strait Islander women up to 1991 were derived using data collected in the Australian Censuses (Gray, 1997). With improvements in coverage, birth registration data has been used for 1996 onwards.

The TFRs for Aboriginal and Torres Strait Islander women for the period 1996 to 2012 were derived using the number of births registered to Aboriginal and Torres Strait Islander mothers, and estimates of the female Aboriginal and Torres Strait Islander population. As these estimates are derived from different censuses, TFRs for Aboriginal and Torres Strait Islander women for 1996 to 2012 are not strictly comparable.

2.6 Total Fertility Rates(a), Australia, 1962-2012
Graph: 2.6 Total Fertility Rates(a), Australia, 1962–2012



Choice of fertility assumption

In summary, while fertility rates based on birth registrations of Aboriginal and Torres Strait Islander children may provide some evidence for assuming constant or increasing Aboriginal and Torres Strait Islander fertility, cohort fertility rates based on the 'children ever born' question asked in the Census indicate long-term declines. Assumptions that take both sets of evidence into account have been made but with more emphasis given to the 'children ever born' data. Given the long-term trend of declining fertility in Census data, three assumptions including a constant fertility rate and decreasing fertility rates were chosen. The magnitude and duration of any future changes in fertility rates are not possible to gauge accurately.


Method used to produce fertility assumptions

Assumed age-specific fertility rates for Aboriginal and Torres Strait Islander women are based on three years of birth registrations (2010 to 2012) in order to minimise the effect of year-to-year fluctuations in registrations. These rates were adjusted to produce plausible numbers of projected births in the first year of the projection period in accordance with Aboriginal and Torres Strait Islander population estimates at younger ages.

Adjustment factors were calculated for each state and territory by taking the ratio of the number of Aboriginal and Torres Strait Islander children aged 0, 1 and 2 at 30 June 2011 to the number of births registered between 2010 and 2012. Differences in the two sources can be attributed to several factors. These include net undercount, Census records for which Indigenous status was not stated, lags in the registration of births and differences in the method of identification between the Census and the Birth Registrations collection (for example, a child born to an Aboriginal and Torres Strait Islander and non-Indigenous parent is automatically identified as Aboriginal and Torres Strait Islander in birth registrations, however the child may be identified as non-Indigenous on the Census form). For each state and territory, the 2010-2012 age-specific fertility rates were then multiplied by the relevant adjustment factor to produce adjusted age-specific fertility rates.

In addition, as rates are required on a financial year basis, they were adjusted to account for the six-month period between the mid-point of the period 2010-2012 (calendar year fertility rates) and 2011-12 (financial year fertility rates).

Although there is some evidence of greater declines in fertility in the younger age groups relative to older age groups, analysis suggests that incorporating this trend into the fertility assumptions would have a negligible effect on the future size of the Aboriginal and Torres Strait Islander population. Therefore, the assumed 0.5% annual decline in fertility rates for Series B is applied uniformly across relevant age groups.

2.7 ASSUMED FERTILITY RATES, States and territories

AGE-SPECIFIC FERTILITY RATES(a)
15-19(b)
20-24
25-29
30-34
35-39
40-44
45-49(c)
TFR(d)

YEAR ENDED 30 JUNE 2012

NSW
54.7
126.3
121.2
88.7
38.9
9.2
0.4
2.20
Vic.
47.5
94.3
111.8
85.9
51.4
12.4
1.2
2.02
Qld
74.1
145.3
128.6
94.7
45.8
11.0
0.8
2.50
SA
64.9
127.6
109.2
82.0
38.7
6.1
-
2.14
WA
76.7
122.8
110.0
75.6
35.8
8.3
0.8
2.15
Tas.
46.3
106.4
112.2
83.8
36.5
8.7
-
1.97
NT
86.2
129.5
105.8
79.4
35.7
9.0
0.2
2.23
ACT
49.1
59.3
88.3
61.7
67.1
5.8
3.8
1.68
Aust.(e)
66.1
127.8
117.9
86.5
41.0
9.5
0.6
2.25

YEAR ENDED 30 JUNE 2026

NSW
51.0
117.7
113.0
82.7
36.3
8.6
0.3
2.05
Vic.
44.3
87.9
104.2
80.1
47.9
11.6
1.1
1.89
Qld
69.1
135.5
119.8
88.3
42.7
10.2
0.8
2.33
SA
60.5
118.9
101.8
76.5
36.0
5.7
-
2.00
WA
71.5
114.5
102.6
70.4
33.4
7.8
0.8
2.00
Tas.
43.2
99.2
104.6
78.1
34.0
8.1
-
1.84
NT
80.4
120.7
98.6
74.0
33.2
8.4
0.2
2.08
ACT
45.8
55.3
82.3
57.5
62.5
5.4
3.6
1.56
Aust.(e)
61.6
119.1
109.9
80.6
38.2
8.9
0.6
2.09

- nil or rounded to zero (including null cells)
(a) Births per 1,000 Aboriginal and Torres Strait Islander women.
(b) Includes births to mothers aged less than 15 years.
(c) Includes births to mothers aged 50 years and over.
(d) Births per Aboriginal and Torres Strait Islander woman.
(e) Includes Other Territories.



Regional variations in fertility

Indigenous Regions

In some previously published ABS projections of the Aboriginal and Torres Strait Islander population, fertility assumptions for sub-state geographies used the corresponding state and territory level assumption. The projections presented in this release apply fertility assumptions for sub-state geographies by aggregating Indigenous Regions (IREGs) into two groups for each state and territory (except Tasmania and the Australian Capital Territory):
  • capital city IREG (for example, Adelaide IREG); and,
  • rest of state/territory IREGs combined (for example, Port Augusta IREG and Port Lincoln - Ceduna IREG combined).

Fertility rates for each of these groups were adjusted in a similar manner to state and territory rates to produce plausible numbers of projected births in the first year of the projection period in accordance with Aboriginal and Torres Strait Islander population estimates at younger ages.

2.8 ASSUMED TOTAL FERTILITY RATES(a), Indigenous Regions

30 June 2012
30 June 2026

Sydney IREG
1.89
1.76
Rest of NSW
2.35
2.19
Melbourne IREG
1.66
1.54
Rest of Vic.
2.34
2.18
Brisbane IREG
2.11
1.96
Rest of Qld
2.71
2.53
Adelaide IREG
2.15
2.00
Rest of SA
2.08
1.94
Perth IREG
1.93
1.80
Rest of WA
2.29
2.14
Tasmania IREG
1.97
1.84
Darwin IREG
2.04
1.90
Rest of NT
2.30
2.14
ACT IREG
1.68
1.56
Australia(b)
2.25
2.09

(a) Births per Aboriginal and Torres Strait Islander woman.
(b) Includes Other Territories.


Remoteness Areas

Assumed fertility rates for Remoteness Areas were calculated and adjusted using the same technique as for the states and territories.

2.9 ASSUMED TOTAL FERTILITY RATES(a), Remoteness Areas

30 June 2012
30 June 2026

Major Cities
1.92
1.79
Inner and Outer Regional
2.45
2.29
Remote and Very Remote
2.41
2.25
Australia(b)
2.25
2.09

(a) Births per Aboriginal and Torres Strait Islander woman.
(b) Includes Other Territories.





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