Infertility is generally defined as the inability of a couple to conceive after at least one year of unprotected intercourse. This condition can be further classified as following

1. Primary infertility, in which no previous pregnancy has been occurred.
   
2. Secondary infertility, in which a prior pregnancy, although not necessarily a live birth, has been occurred.

            Infertility affects approximately 1.5 millions out of 10 millions of reproductive-age couples in Thailand.