Single versus double intrauterine insemination in stimulated cycles for subfertile couples

Undertaking intrauterine insemination (IUI) twice in a menstrual cycle instead of the usual single attempt has been shown to increase pregnancy rates. IUI places sperm directly into the uterus and therefore close to any egg(s). The insemination is less stressful, invasive and expensive than in vitro fertilisation and similar procedures. It is therefore often used when a male partner is subfertile, or when the reason for not becoming pregnant is unknown. Generally, IUI is carried out once in a menstrual cycle, but it is sometimes attempted twice (double IUI). The review revealed that, in trials of IUI (where fertility drugs to stimulate the release of eggs are also used), double IUI has resulted in more pregnancies than single IUI.

Authors' conclusions: 

Based on the results of pregnancy rate per couple in five trials, double intrauterine insemination resulted in significant benefit over single intrauterine insemination in the treatment of subfertile couples with husband semen. If advice is to be offered regarding clinical practice, further research is warranted.

Read the full abstract...

Intrauterine insemination, with or without controlled ovarian hyperstimulation, is one of the treatment modalities offered to couples who have tried to conceive for at least one year (subfertile couples). It has been suggested that increasing the number of inseminations from one per cycle to two could increase the probability of conception.


To determine if there is a difference in live birth or pregnancy rates for subfertile couples using single or double intrauterine insemination in stimulated cycles.

Search strategy: 

We searched the Cochrane Menstrual Disorders and Subfertility Group Trials Register (searched June 2007), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2006, issue 2), MEDLINE (January 1966 to June 2007), EMBASE (January 1988 to June 2007), SCIENCE Direct Database (January 1966 to June 2007), Confsci (January 1973 to 15 June 2007), Pascal (January 1984 to June 2007), and the reference lists of articles. We also contacted researchers in the field.

Selection criteria: 

Randomised controlled, parallel trials of single versus double intrauterine inseminations in simulated cycles in subfertile couples.

Data collection and analysis: 

Two reviewers independently assessed trial quality and extracted data. We contacted study authors for additional information.

Main results: 

We identified six studies involving 1785 women. There were no data for the main outcome measure of live birth per couple or ongoing pregnancy rates, and no authors presented comparative data for adverse events. The results of five studies that reported pregnancy rate per couple showed a significant effect of using double insemination (Peto odds ratio 1.8, 95% confidence interval 1.4 to 2.4).