New research has added to the growing body of evidence linking water pollution with the need for infertility treatment
Scientists at the universities of Brunel, Exeter and Reading and the Centre for Ecology & Hydrology have shown how chemicals that block the function of the male hormone testosterone are finding their way into rivers.
The chemicals, which are contained in some medicines and pesticides, appear to cause feminising effects in male fish, raising the possibility that they may have a similar effect in humans.
Lead author Dr Susan Jobling, from Brunel University's Institute for the Environment, said: "The new research findings illustrate the complexities in unravelling chemical causation of adverse health effects in wildlife populations and re-open the possibility of a human - wildlife connection in which effects seen in wild fish and in humans are caused by similar combinations of chemicals."
Dr Jobling noted that the team is still not sure where the chemicals are coming from and revealed that they now hope to identify the source and test their effects.
A young couple with normal fertility have a one-in-five chance of conceiving in each menstrual cycle, assuming they have regular intercourse.
It is therefore not uncommon for couples to seek advice if they have not conceived after six months of trying.