Twenty-one studies (five RCTs) were included in the review (total number of participants not stated). Follow-up in the RCTs ranged from eight months to 5.8 years and across the observational studies varied from six months to 15 years. All RCTs had unclear methods of blinding and three of the five had problems with randomisation and allocation concealment. Observational studies were prospective in design, but used historical controls and scored from 4 to 7 out of 7 on the quality scale.
GnRHa was beneficial in preserving the menstrual cycle (RR 0.26, 95% CI 0.22 to 0.34; 15 studies, 681 patients) and increasing pregnancy rates (RR 1.51, 95% CI 1.01 to 2.28; 10 studies). Results based on RCTs only did not find a statistically significant benefit for either outcome. There was no significant difference in marker levels in patients treated with GnRHa (three studies). Adverse events were not described in the included studies.
One study with 214 participants showed a positive effect for oral contraceptives in reducing amenorrhea rates mainly in women under 30 years. Four smaller studies (sample sizes of 90, 44, 33 and nine) found no significant effect.