Double versus single homologous intrauterine insemination for male factor infertility: a systematic review and meta-analysis

Male factor infertility affects 30%–50% of infertile couples worldwide, and there is an increasing interest in the optimal management of these patients. In studies comparing double and single intrauterine insemination (IUI), a trend towards higher pregnancy rates in couples with male factor infertility was observed. Therefore, we set out to perform a meta-analysis to examine the superiority of double versus single IUI with the male partner''s sperm in couples with male factor infertility. An odds ratio (OR) of 95% confidence intervals (CIs) was calculated for the pregnancy rate. Outcomes were analysed by using the Mantel–Haesel or DerSimonian–Laird model according to the heterogeneity of the results. Overall, five trials involving 1125 IUI cycles were included in the meta-analysis. There was a two-fold increase in pregnancies after a cycle with a double IUI compared with a cycle with a single IUI (OR: 2.0; 95% CI: 1.07–3.75; P<0.03). Nevertheless, this result was mainly attributed to the presence of a large trial that weighted as almost 50% in the overall analysis. Sensitivity analysis, excluding this large trial, revealed only a trend towards higher pregnancy rates among double IUI cycles (OR: 1.58; 95% CI: 0.59–4.21), but without statistical significance (P=0.20). Our systematic review highlights that the available evidence regarding the use of double IUI in couples with male factor infertility is fragmentary and weak. Although there may be a trend towards higher pregnancy rates when the number of IUIs per cycle is increased, further large and well-designed randomized trials are needed to provide solid evidence to guide current clinical practice.