Repeating episodes of low fecundability. A multicentre European study. The European Study Group on Infertility and Subfecundity.

Many reproductive failures tend to repeat themselves within the same couple. Whether fecundability (the probability of conceiving in a given number of menstrual cycles) follows the same pattern is studied using data from the European Studies on Infertility and Subfecundity (ESIS): 6630 women were interviewed on 'time to pregnancy' (TTP) and other aspects of their pregnancy history. Surveys were conducted between 1991 and 1994 in seven regions from five European countries. Furthermore, the pattern of fecundability in this population was compared with results from computer simulations based upon a population with fixed fecundability parameters. Results from ESIS speak in favour of the stability of fecundability in the relatively short reproductive life of a couple. However, a substantial proportion of couples with up to two events of subfecundability (TTP >9.5 months) became pregnant shortly after trying again. This finding calls for reservation in starting expensive and/ or unpleasant diagnostic procedures at an early stage when a couple tries to become pregnant again.