Does increasing the number of inseminations per cycle increase the probability of conception? a randomized trial comparing single versus double intrauterine insemination

Background: Intrauterine insemination (IUI) remains an inexpensive, non-invasive, and effective first-line artificial insemination technique. The technique of IUI has evolved through various innovations since the time Cohen published the first report of IUI in 1962, and the success rate increased from 5% to >20%. The success of IUI depends upon several factors; two such prognostic factors are the timing and frequency of insemination.  The objective of this study was to compare the effectiveness of single versus double intrauterine insemination.Methods: This prospective randomized study was carried out in 130 patients with male factor infertility, PCOS and unexplained infertility. Patients were randomly assigned into two groups. In the first group of 65 patients, single IUI was applied at 36 to 40 hours after HCG administration, to the other 65 patients in the second group, double IUIs were applied at 12 to 16 hours and 36 to 40 hours after HCG administration. The primary end-point of the study was to compare the clinical pregnancy rate between the two groups.Results: The overall pregnancy rate was 18.46% (12/65) for single IUI group and 30.76% (20/65) for double IUI group. There was a no statistically significant difference between single and double IUI groups (p=0.16).Conclusions: This study did find a higher pregnancy rate following double IUI; however, the difference was not statistically significant. Further, larger sample size studies are required to determine if double IUI increases the pregnancy rate.