This study is a prospective randomized trial with 242 IUI cycles. Patients are randomized in two groups including 121 patients in each group. In the first group, the patients will be treated with triptoreline (Gonapeptyl®) in their luteal phase. As for the other group, the patients will undergo the luteal phase without any supportive medication. This study is going to clarify the role of the gonadotropin agonist (triptoreline, Gonapeptyl®) as a luteal phase supporter. The benefit of the treatment is measured by the numbers in the live birth and clinical pregnancy rates.