The epidemiology of male infertility.

The purpose of this review is to integrate understanding of epidemiology and infertility. A primer on epidemiologic science and an example disease for which the design of epidemiologic investigations is readily apparent are provided. Key features of infertility that limit epidemiologic investigation are described and a survey of available data on the epidemiology of infertility provided. Finally, the work that must be completed to move this area of research forward is proposed, and, with this new perspective of "infertility as a disease," improvements envisioned in public health that may be gained through improved understanding of the epidemiology of male infertility.