3. Part I: Reconstruction of the Religious Composition in 2016
3.3. Fertility – Data and Method
Computation of fertility rates requires information on a) the number of live births to mothers by age and their religious affiliation, and b) number of women of reproductive
age (generally 15 to 49 years) of different religious affiliation. While Statistik Austria collects and publishes data on the religion of mothers of every child born in Austria, and also by Federal States (birth register)14, the data on number of women by age and religion (exposure) are not available from the Central Register of Residence (ZMR). The most recent available data for both data series pertain to 2001. Beyond this year, religious composition of Austria’s population had to be estimated. Thus, the data on women by age and religion that enter fertility calculations are derived from the reconstruction based on the census 2001, migration statistics 2001-2015 (random migrant assumption for religion), and mortality and secularisation trends, as detailed in the reconstruction section of the report.
The information on the religion of the mother that is available from the birth register suffers from several deficiencies for our purposes, particularly since the data are recorded in pre-defined categories that in some cases differ from our definitions. The birth register information on religious affiliation is limited to the following categories: Roman Catholic, Protestant (‘Evangelic’), Old Catholic, Jewish, Muslim, Jehovah Witnesses, no religion or unknown, and other registered religions. Live births to Orthodox women, who are a significant group both in Vienna and in Austria, are included in the ‘Others’ residual category. Those with no religion and unknown/unreported religion are aggregated into a single category whose size is increasing as more and more mothers do not report any religion. Therefore, we made the following adjustments:
- We have assumed the same age-specific fertility rates for Orthodox women in Austria as for all women;
- In order to suppress the effect of the non-reporting of religious affiliation we assumed fixed differentials (ratio) between the total fertility rate of women with no religion and the overall total fertility rate in Austria,
- Other religions is a residual category. Live births in this category were computed as the difference between all live births and live births to women in other categories (Roman Catholic, Protestant, Muslim, Orthodox, None).
Overall, this means that the fertility rate estimates are more reliable for Roman Catholics, Protestants and Muslims than for the other groups. Uncertainty is highest for Orthodox and Others.
Since the reconstruction was performed in 5-year steps, fertility rates are presented for 5-year periods.
Vienna
In Vienna the religiously unaffiliated constitute a significant share of the population of women in reproductive ages (24% in 2001 compared to 11% in Austria). The data on live births seem not to be affected by non-reporting as much as for the whole of Austria. Thus, 14Religion of the mother is available until 2015. Due to increasing non-response in the reporting of religion of mothers and fathers, Statistics Austria will not publish any data on the religion of parents beyond 2015.
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we made no adjustments to live birth data for Vienna. For Orthodox and Others we use the same fertility rates that are identical to the average for this broad group. Counts of women by age and religion were obtained using the same procedure as detailed above for Austria.
3.3.1. Results
Austria
Total fertility rate (TFR)15 has been on an upward trajectory in Austria throughout the 21st century. Between 2001 and 2015, TFR for all women in Austria increased from 1.36 to 1.49 (Zeman et al. 2015; Statistik Austria 201616) and it changed from 1.38 to 1.45 between 2001- 2005 and 2011-2015 (see Figure 10). These are relatively low values in comparison to some other European countries and Austrian fertility is consistently slightly below the EU average, however, very similar levels are seen across the German-speaking and neighbouring countries to Austria (VID and IIASA 2016).
The TFRs of Christians and unaffiliated women followed the general increasing trend, with the largest gains among the unaffiliated (+0.09) and Roman Catholics (+0.08). In spite of a moderate increase, TFR has been below 1.5 children per woman with small variation across the religious groups except for Muslims. Unlike for other groups, Muslim fertility has been declining and dropped to 2.26 children per woman in 2011-2015. As a result, the gap between the fertility of Muslims and overall TFR of Austrian women has narrowed down: in 2001-2005, Muslim TFR was double the average of Austria but in 2011-2015 it was 56% higher.
15 Total fertility rate (TFR) is an estimate of the number of children who would be born to women in reproductive age at a given calendar period if they were to pass through the childbearing schedule of that period. Thus, TFR is not equivalent to lifetime fertility of these women, but an estimate based on the situation in a given year. Due to changes in age at childbearing, TFRs can differ substantially compared to actual lifetime fertility.
16 http://www.statistik.at/web_en/statistics/PeopleSociety/population/births/index.html (last accessed on February 28, 2017).
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Figure 10: Total Fertility Rates by religion, Austria
Source: Statistik Austria birth register, authors’ calculations.
Women of no religious affiliation used to have the lowest fertility rates; however, this has changed and in 2011-2015 Protestant women were the lowest fertility group. Their TFRs remain below the lowest-low fertility threshold (defined as 1.3 children per women by Kohler, Billari and Ortega (2002)).
One trend that is common for women of all religious groups is postponement of childbearing towards later age. This is true also for Muslim women, who still have high fertility in their 20s, but between 2001-2005 and 2011-2015 their teenage fertility as well as fertility rates at age 20-24 declined significantly (see Figure 11).
Figure 11: Fertility age schedules for women by religious affiliation, Austria
Source: Statistik Austria birth register, authors’ calculations.
Roman Catholic, Protestant and unaffiliated women have very similar childbearing age patterns, typical with highest fertility rates at age 30-34 and fertility increases among women 35 and older. For the Orthodox and Others the data are too scarce to make meaningful observations.
Overall we can conclude that the religious differentials have been narrowing down since 2001 and the data are in agreement with the fertility convergence hypothesis.
Vienna
Compared to Austria, TFRs of Viennese women are practically identical during the three observed periods (1.38 in 2001-2005, 1.41 in 2006-2010, 1.44 in Vienna compared to 1.45 in Austria in 2011-2015). Fertility has increased and variation across the religious groups has declined in both. Similarly to Austria, TFRs of the unaffiliated (+0.23) and Roman Catholic women (+0.22) increased the most (see Figure 12). Viennese Roman Catholic and Protestant women have their children at much later age – mostly after age 30 – compared to women in the rest of Austria. Fertility of Muslim women has declined more rapidly in Vienna than in Austria overall (-0.1). Due to the substantial influx of immigrants from predominantly Muslim countries, and the significant share of asylum seekers finding lodgings in Vienna, these recent arrivals have boosted the number of women in reproductive age. In 2011-2015 the number of births to Muslim women reported in the birth register declined and the TFR dropped as well. However, fewer births may not be the main reason why we observed lower TFR. In the same period, and particularly in 2015, the number of Muslim women in reproductive age increased sharply as a result of intensified migration. It is possible that the declining number of births really means a declining fertility rate, since the number of births declined, but the fertility rates are sensitive to changes in the size and composition of the female population17 and a significant number of recently arrived Muslim women may have shifted the TFRs downwards. The largest decline occurred in young ages below 25, and we know that most new immigrant were young. If the change in fertility rates is mainly due to a declining intensity of childbearing, this would be symptomatic of transition towards below- replacement fertility. Although Muslim women differ in their reproductive behaviour from Christian and unaffiliated women, these differences are diminishing over time (see Figure 13).
17 Fertility rates are computed as a ratio between recent number of births and number of women in age group 15-49, thus an abrupt change in the number of female population results in a changing rate even if there was no behavioural change.
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Figure 12: Total Fertility Rates by religion, Vienna
Source: Statistik Austria birth register, authors’ calculations.
Figure 13: Fertility age schedules for women by religious affiliation, Vienna
Source: Statistik Austria birth register, authors’ calculations