Reviewing intra-uterine insemination for couples with unexplained infertility

This review looked at whether intrauterine insemination (IUI) improves pregnancy rates in couples with unexplained infertility. It found that IUI benefits couples with a low predicted chance of natural conception.

For one-quarter of couples with infertility, there is no clear cause. IUI is a treatment option for couples with unexplained infertility. IUI involves injecting sperm directly into the uterus (womb). IUI can be used with ovarian hyperstimulation (OH), in which medications cause the ovaries to release multiple eggs. Alternately, a natural cycle (NC) protocol can be used. In NC-IUI, the woman's menstrual cycle is monitored and IUI is done following ovulation (the release of an egg).

OH-IUI can cause multiple pregnancies (twins or triplets), which are dangerous for both the mother and the babies. This risk can be reduced using rules to cancel the IUI if three or more eggs develop.

It is unclear whether IUI improves outcomes for couples with unexplained infertility.

This review analyzed the results of 15 trials with 2068 women with unexplained infertility.

It was uncertain whether NC-IUI is beneficial compared to natural conception. However, there was a trend toward higher birth rates with NC-IUI. It was unclear whether IUI affected the risk of miscarriage or multiple pregnancies.

OH-IUI may improve the chance of conception compared to OH with timed intercourse. Based on 6 trials with 517 women, if the pregnancy rate is 23% through OH and timed intercourse, then it would be between 26% and 44% using OH-IUI. There was a trend toward a higher risk of multiple pregnancies using OH-IUI.

There was moderate evidence that OH-IUI increases birth rates for women with a low predicted chance of natural conception. If the pregnancy rate would be 9% through natural conception, then it would be between 17% and 50% using OH-IUI. However, there was no benefit to OH-IUI for women with a moderate predicted chance of pregnancy.

There was moderate evidence that NC-IUI increases birth rates compared to OH with intercourse. If the birth rate is 13% using OH with intercourse, it would be between 14% and 34% with NC-IUI.

This review found that OH-IUI results in higher pregnancy rates than natural conception for couples with a low predicted rate of natural conception. It also found that NC-IUI leads to a higher birth rate than OH with intercourse.

Cochrane reviews use particularly strict criteria. The authors found the trials analyzed to be of very low to moderate quality, which led to fewer conclusions.