In almost half the cases of subfertility, there is a male contribution to the problem. The initial investigation / tests requires a sample of semen for analysis. This is usually produced at home after abstaining from ejaculation for 2 to 3 days. A shorter time than this will reduce the total number and longer abstinence can lead to a falsely high number of poorly motile (slow swimming) sperms. The sample needs to be delivered to the laboratory within one hour for analysis.