To show that male fertility is declining is not simple. Few men volunteer and recruitment bias may lead to over-representation of the subfertile. Semen analysis has errors arising from counting and poorly standardized criteria, which may be overcome by automation. Time to pregnancy (TTP)-the number of menstrual cycles taken to conceive-measures fertility and allows male recruitment bias to be estimated. We review automated measurement of sperm concentration, motility and morphology and present a preliminary report on a study to assess a retrospective TTP questionnaire, recruitment bias and feasibility for large-scale surveillance of fertility.