Younger women with ovulation disorders and unexplained infertility predict a higher success rate in superovulation (SO) intrauterine insemination (IUI).

INTRODUCTION Superovulation-intrauterine insemination (SO-IUI) is the most common assisted reproductive technique (ART) in the world, with good evidence of efficacy and cost-effectiveness. However, parameters affecting its success have not been consistently reported. So in this study, we aim at determining the parameters influencing the success rate of SO-IUI. MATERIALS AND METHODS We conducted a retrospective cohort study of 797 SO-IUI cycles from 606 patients, performed between 2007 and 2009 in a single centre. These women received clomiphene citrate (CC), recombinant FSH (rFSH) or both. RESULTS There were 127 clinical pregnancies with a pregnancy rate (PR) of 15.9% (127/797) per treatment cycle. Factors associated with higher PR included maternal age <38 (P = 0.02), subfertility diagnoses of ovulatory disorders, unexplained infertility, sexual dysfunction and unilateral tubal obstruction (P = 0.02), an endometrial thickness ≥8 mm (P = 0.03), total number motile spermatozoa (TNMS) of ≥1 million (P = 0.03), and spermatozoa normal forms (NF) ≥4% (P <0.01) on bivariate analysis. When CC is used, the endometrial thickness is more likely to be suboptimal (<8 mm). All the above parameters remained significant except the subfertility diagnoses on multivariate analysis. CONCLUSION Patients' selection with women <38 years old and preferably with ovulation disorders and unexplained infertility is associated with the highest PR in SO-IUI. Cycle parameters such as the use of rFSH alone, with the avoidance of CC, TNMS ≥1 million and NF ≥4% is likely to result in the best outcomes and reduce the high order multiple pregnancy risk.