A Cochrane review included 14 trials involving a total of 1 866 women.
There was evidence of an increased chance of pregnancy with intra-uterine insemination (IUI) compared to timed intercourse (TI), both in stimulated cycles, (OR 1.68, 95% CI 1.13 to 2.50, 6 trials, n=517). For women where IUI with ovarian hyperstimulation (OH) was compared with IUI in a natural cycle, there was an increase in pregnancy rate (OR 2.33, 95% CI 1.46 to 3.71, 3 trials, n=415) and live birth rate (OR 2.07, 95% CI 1.22 to 3.50, 4 trials, n=396). Most of the trials provided insufficient data to investigate several important outcomes including live birth, multiple pregnancies, miscarriage and risk of ovarian hyperstimulation. There was no evidence of a difference in pregnancy rate for IUI with OH compared with TI in a natural cycle (OR 4.05, 95% CI 0.39 to 41.87, 1 trial, n=51).
Comment: There is insufficient data on multiple pregnancies and other adverse events for treatment with OH.
The quality of evidence is downgraded by study quality (unclear allocation concealment) and by imprecise results (limited study size for each comparison).