Increasing Childlessness or Fewer Families with Many Children?
The decline of fertility in the course of the Second Demographic Transition is mainly caused by both an increase in childlessness and a decline of large families (three or more births). In the recent issue of KZfSS, Martin Bujard and Harun Sulak from the BiB measure the extent of both effects on the decline of fertility in Germany since the 1960s.
Which of these effects are stronger in Germany? This question has been contested for a long time. However, an exact quantification of the particular effects was missing.
Therefore, Martin Bujard and Harun Sulak developed a decomposition method which allows calculating the effects of the particular parity changes between cohort total fertility rates (CTFR) of different cohorts. They applied this method in order to compare German CTFRs for the cohorts the fertility decline occurred in, namely the cohorts between 1933 and 1968. The analyses were differentiated by regions and periods. Generally, the CTFR decline can be separated into four components: increasing childlessness, decreasing shares of higher order births (3+), a combined effect and a changing relation of first and second births.
On this basis, the two BiB researchers found out that the effect of the increasing childlessness accounts for 26% of the CTFR decline in Germany, the decreasing higher order births for 68% and the combined effect for 6%. The relation of first and second births changed only marginally. Remarkably, these figures are based on two entirely different periods: The CTFR decline between the cohorts of 1933 and 1947 is solely based on the decline of women with three or more children. However, two thirds of the CTFR decline since 1947 is caused by an increasing childlessness.
The results are relevant for fertility theories because increasing childlessness and decreasing higher order births have different reasons.
Martin Bujard, Harun Sulak (2016): "Mehr Kinderlose oder weniger Kinderreiche?" Eine Dekomposition der demografischen Treiber in unterschiedlichen Phasen des Geburtenrückgangs in Deutschland. In: Kölner Zeitschrift für Soziologie und Sozialpsychologie 68,3: 487–514