Fertility in Populations and in Patients: Population studies on natural fertility and prediction of treatment outcome in anovulatory infertile patients

Abstract

In most western societies, reproductive behavior is nowadays controlled to a high degree: observed fertility patterns in a population -how many children do couples get and when do they get them- are the result of choices made by individuals rather than biological factors. This is in marked contrast with previous times, in which it was the biological destiny of women to have children - or to remain childless involuntarily. The driving force behind the change that has occurred is undoubtedly the availability of reliable contraception (Leridon, 1998), which has gone hand in hand with changes in social attitudes with respect to reproduction (e.g. secularization, emancipation of women (Blossfeld, 1995)). In many Western European societies, the number of children per woman has dropped below the natural replacement level (Von Cube, 1986), and everywhere couples who want to have children carefully plan when to have them. In many countries women delay childbearing to later age, the most pronounced example being the Netherlands in which the mean age at first childbirth has risen from 24.6 years in 1970 to 29.2 years in 2001. Since pregnancy chances decrease with age of the women (Schwartz and Mayaux, 1982) (van Noord-Zaadstra et al., 1991), postponement of the first child has led to an increase in incidence of subfertility (te Velde, 1991).