Background Intra-uterine insemination (IUI) is a widely used fertility treatment for couples with unexplained subfertility. Although IUI is less invasive and less expensive thAppendixan in vitro fertilisation (IVF), the safety of IUI in combination with ovarian hyperstimulation (OH) is debated. The main concern about IUI treatment with OH is the increase in multiple pregnancy rate. This is an update of a Cochrane review (Veltman-Verhulst 2012) originally published in 2006 and updated in 2012. Objectives To determine whether, for couples with unexplained subfertility, IUI improves the live birth rate compared with timed intercourse (TI), or expectant management, both with and without ovarian hyperstimulation (OH). Search methods We searched the Cochrane Gynaecology and Fertility (formerly Cochrane Menstrual Disorders and Subfertility Group) Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, inception to Issue 11, 2015), Ovid MEDLINE, Ovid EMBASE, PsycINFO and trial registers, all from inception to December 2015 and reference lists of articles. Authors of identified studies were contacted for missing or unpublished data. The evidence is current to December 2015. Selection criteria Truly randomised controlled trial (RCT) comparisons of IUI versus TI, in natural or stimulated cycles. Only couples with unexplained subfertility were included. Data collection and analysis Two review authors independently performed study selection, quality assessment and data extraction. We extracted outcomes, and pooled data and, where possible, we carried out subgroup and sensitivity analyses. Main results We included 14 trials including 1867 women. IUI versus TI or expectant management both in natural cycle Live birth rate (all cycles) There was no evidence of a difference in cumulative live births between the two groups (Odds Ratio (OR) 1.60, 95% confidence interval (CI) 0.92 to 2.78; 1 RCT; n = 334; moderate quality evidence). The evidence suggested that if the chance of a live birth in TI was assumed to be 16%, that of IUI would be between 15% and 34%. Multiple pregnancy rate There was no evidence of a difference in multiple pregnancy rate between the two treatment groups (OR 0.50, 95% CI 0.04 to 5.53; 1 RCT; n = 334; moderate quality evidence). IUI versus TI or expectant management both in stimulated cycle Live birth rate (all cycles) There was no evidence of a difference between the two treatment groups (OR 1.59, 95% CI 0.88 to 2.88; 2 RCTs; n = 208; I-2 = 72%; moderate quality evidence). The evidence suggested that if the chance of achieving a live birth in TI was assumed to be 26%, the chance of a live birth with IUI would be between 23% and 50%. Multiple pregnancy rate There was no evidence of a difference in multiple pregnancy rates between the two treatment groups (OR 1.46, 95% CI 0.55 to 3.87; 4 RCTs, n = 316; I-2 = 0%; low quality evidence). IUI in a natural cycle versus IUI in a stimulated cycle Live birth rate (all cycles) An increase in live birth rate was found for women who were treated with IUI in a stimulated cycle compared with those who underwent IUI in natural cycle (OR 0.48, 95% CI 0.29 to 0.82; 4 RCTs, n = 396; I-2 = 0%; moderate quality evidence). The evidence suggested that if the chance of a live birth in IUI in a stimulated cycle was assumed to be 25%, the chance of a live birth in IUI in a natural cycle would be between 9% and 21%. Multiple pregnancy rate There was no evidence of a difference in multiple pregnancy rate between the two treatment groups (OR 0.33, 95% CI 0.01 to 8.70; 2 RCTs; n = 65; low quality evidence). IUI in a stimulated cycle versus TI or expectant management in a natural cycle Live birth rate (all cycles) There was no evidence of a difference in live birth rate between the two treatment groups (OR 0.82, 95% CI 0.45 to 1.49; 1 RCT; n = 253; moderate quality evidence). The evidence suggested that if the chance of a live birth in TI or expectant management in a natural cycle was assumed to be 24%, the chance of a live birth in IUI in a stimulated cycle would be between 12% and 32%. Multiple pregnancy rate There was no evidence of a difference in multiple pregnancy rate between the two treatment groups (OR 2.00, 95% CI 0.18 to 22.34; 2 RCTs; n = 304; moderate quality evidence). IUI in natural cycle versus TI or expectant management in stimulated cycle Live birth rate (all cycles) There was evidence of an increase in live births for IUI (OR 1.95, 95% CI 1.10 to 3.44; 1 RCT, n = 342; moderate quality evidence). The evidence suggested that if the chance of a live birth in TI in a stimulated cycle was assumed to be 13%, the chance of a live birth in IUI in a natural cycle would be between 14% and 34%. Multiple pregnancy rate There was no evidence of a difference in multiple pregnancy rate between the groups (OR 1.05, 95% CI 0.07 to 16.90; 1 RCT; n = 342; moderate quality evidence). The quality of the evidence was assessed using GRADE methods. Quality ranged from low to moderate, the main limitation being imprecision in the findings for both live birth and multiple pregnancy.
