IRCT138901283737N1 IRCT 2010-04-28 Tehran Medical Sciences University Increase in pregnancy rate of infertile couples The effect of luteal phase support by a progestogen drug (cyclogest)on pregnancy rates of stimulated IUI cycles of 98 infertile couples (study group) with unexplained infertility that were compaired with stimulated IUI cycles of 102 infertile couples (control group) without drug taking for luteal phase support 2007-09-01 anticipated 200 Complete https://irct.ir/trial/3848 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment. 0 (exploratory trials) Female infertility. Intervention 1: in study group:Cyclogest/400 mg every night/in luteal phase/ if pregnancy happen, this drug will continue till 10 weeks/ if pregnancy does not happen, the drug will continue till14 nights. Intervention 2: in control group: no drug receiving in luteal phase.