Waiting time to pregnancy as a measure of fertility postponement and reproductive ageing. Application of a self-administered questionnaire in Poland.

Krzysztof Tymicki, Warsaw School of Economics

Decrease of fecundity with age also called reproductive ageing is a well known phenomenon among humans. Apparent fecundability reaches it’s peak at age 22 an decreases quickly afterwards: fecundity at age 32 is an equivalent to fecunditz at age 15. The process of reproductive ageing seems to be of a crucial importance when taking into account that a main component of contemporary reproductive behavior is postponement of reproduction. It might result in biological consequences such as an increase in incidence of subfecundity, an increase in incidence of miscarriages or fetal malformation. On the other hand, these biological consequences might be translated into demographic consequences such as an increase in a proportion of childless women, a number of children below planned (lower quantum) or a lack of the recuperation effect. Therefore, it is necessary to measure the importance of these effects both from the biological and demographic perspectives. In order to account for these two effects, we propose to use the methodology which measures waiting time to pregnancy (WTtP). This methodology assumes that reproductive ageing results in longer waiting time to pregnancy (waiting time to conception) i.e. number of cycles the couple have to wait to conceive taking into account unprotected and regular intercourse. Using this method we aim at estimation of both biological and demographic consequences of fertility postponement. We apply data from the standard self-administered questionnaire in order to measure waiting time to pregnancy among Polish couples. Using this data we try to answer the question about the pace of reproductive ageing, an incidence of problems associated with fecundity and how the fertility postponement is translated into lower rates of reproduction.