How tempo and quantum of fertility changed during a long-term shift to later childbearing: Australia 1976-2006

Peter McDonald, Australian National University
Rebecca Kippen, Australian National University

We investigate the nature of tempo and quantum effects that derive from long-term postponement of births. We use an Australian database for the years 1976-2006 in which fertility is classified simultaneously by single year of age of woman, single parity and single years of duration since the previous birth. In this period, Australian fertility rose from quite young ages to much older ages. For first births, we examine the cross-sectional versus cohort dimensions of the onset, progression and ending of the shift to older age at first birth and the impact on first birth quantum. We test various theoretical possibilities. For second and higher order births, we examine how later childbearing affects the interval from the previous birth and how this affects quantum of these births. The results indicate ways in which future birth trends may be more accurately projected.