A Cochrane review (abstract , review ) included 6 studies (4 randomized, 4 cross-over) with a total of 713 couples. The outcomes were not pooled due to the methodological quality of the trials and variations in the patient characteristics and interventions. In one trial, 17/80 women conceived with one cycle intrauterine insemination (IUI) compared to 3/76 women allocated to one cycle timed intercourse (p< 0.009). In one trial, one pregnancy out of three cycles IUI and none out of four cycles timed intercourse was observed. A twelve-treatment-cycle study reported 2 conceptions/223 cycles with IUI versus 3 conceptions/252 cycles of timed intercourse. Another twelve-treatment-cycle study reported 7 pregnancies/58 cycles IUI in comparison with 4 pregnancies/52 cycles timed intercourse (p>0.05). In a third twelve-treatment-cycle study, 10 conceptions occurred during IUI and none during timed intercourse in 19 women with cervical hostility. One study compared IUI with expectant management; 26 women (51%) in the IUI group and 16 women (33%) in the expectant management group conceived. Of these pregnancies, 22 (43%) vs. 13 (27%) were ongoing (RR 1.6, 95% CI 0.91 to 2.8); 16/22 of the ongoing pregnancies in the IUI group were directly related to the IUI.
Comment: The quality of evidence is downgraded by study quality and by indirectness (differences in studied patients and interventions).