Epidemiology and trends in male subfertility.

The incidence and the causes of male infertility and male reproductive ill-health (in general) are important issues that remain poorly characterised. There does not appear to be a worldwide decline in semen quality but changes are more apparent in some regions than others. Furthermore, though the incidence of testicular cancer and congenital genital malformations had been increasing, the rate of increase has seemingly slowed over the past decade. Demographic data on UK fertility rates also provide scant evidence to suggest that infertility is increasing. Though this incidence data is reassuring, male infertility has been associated with an ever-increasing number of putative risk factors, including current exposures or parental exposures to occupational, lifestyle or environmental factors. It is currently unclear to what extent such risk factors (and others such as DNA damage) influence male infertility. Better characterisation of risk factors will aid our understanding of what is happening to male infertility. This brief review examines recent trends in male infertility and summarises the extent to which knowledge in this area has improved significantly.