Double versus single intrauterine insemination for unexplained infertility: a meta-analysis of randomized trials.

OBJECTIVE To investigate the effect of double versus single intrauterine insemination (IUI) per treatment cycle in women with unexplained infertility. DESIGN Meta-analysis of randomized controlled trials. MAIN OUTCOME MEASURE(S) Clinical pregnancy rates per couple. INTERVENTION(S) Electronic searches of the Cochrane Central Trials Registry and Medline without year and language restriction through March 2009; hand searching of the abstract books of the European Society of Human Reproduction and Embryology and American Society for Reproductive Medicine annual meetings (2001-2008). RESULT(S) Six randomized trials, involving 829 women, were included in the analysis. Fifty-four (13.6%) clinical pregnancies were recorded for treatment with double IUI and 62 (14.4%) for treatment with single IUI. There was no significant difference between the single and double IUI groups in the probability for clinical pregnancy (odds ratio, 0.92; 95% confidence interval, 0.58-1.45; P=0.715). CONCLUSION(S) Double IUI offers no clear benefit in the overall clinical pregnancy rate in couples with unexplained infertility.