A Cochrane review included 25 trials with over 2 400 women. Only 2 studies reported live births. The odds ratio (OR) for pregnancy following ovulation suppression vs. placebo or no treatment for all women randomised was 0.97 (95% CI 0.68 to 1.34) despite the use of a variety of suppression agents. The common OR for pregnancy following all agents vs. danazol for all women randomised was 1.38 (95% CI 1.05 to 1.82). When GnRHa and danazol were directly compared, OR was 1.45 (95% CI 1.08 to 1.95) for all women randomised. In all analyses the data were statistically homogeneous (I²=0%). The other aspect of ovulation suppression is the side effects. These data were statistically homogeneous. They suggest no statistically significant benefit from treatment.
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment, considerable loss to follow up in some of the older studies) and upgraded by consistent findings.