Causes

Introduction 
Infertility affects about 15% of couples in their reproductive age and this percentage seems to be increasing. This trend may also depend also on the delay in decision making for having child. It is well known that ageing in all species leads to a reduction of reproductive potential; in humans it happens consistently after reaching age 30, whatever the infertility cause may be.
There are many causes for infertility. Some are well known others are unknown. In the last decades, especially in industrialised countries the relative proportion of the causes has changed.