Period parity progression measures with continued fertility postponement: a new look at the implications of delayed childbearing for cohort fertility

In this paper we introduce a new set of period parity progression measures with continued fertility postponement in order to account for two distinct implications caused by delays in childbearing: tempo distortions imply an underestimation of quantum of fertility in observed period data, and the fertility aging effect reduces higher parity births because the respective exposure is shifted to older ages where the probability of having another child is quite low. Our measures remove the distortion and provide means to assess the latter aging effect. The measures therefore provide an unified toolkit of fertility measures that (a) facilitate the description and analysis of past period fertility trends in terms of synthetic cohort behavior, and (b) allow the projection of the timing, level and distribution of cohort fertility using the most recently observed period-quantum and tempo changes. Due to their explicit relation to cohort behavior, these measures extend and improve the existing adjustment of the total fertility rate. We apply these methods to Sweden during 1970-1999. (AUTHORS)