Infertility is defined as the inability to conceive after a year of unprotected regular intercourse.  This can be a very stressful situation for a couple, and there are many known causes.  When looking at the reasons why a couple is infertile, 40% of them are typically due to female factors, 40% to male factors and 20%, even after work-up, remain unknown.  There are a variety of tests that can be done to try to determine the cause of infertility.  If a couple meets the criteria for infertility, they should make an appointment with a physician so that an evaluation can be done and an appropriate course of action can be developed.