Progestins versus GnRH analogues for pituitary suppression during ovarian stimulation for assisted reproductive...

This systematic review and meta-analysis of comparative studies investigated whether progestins are as effective as gonadotrophin releasing hormone (GnRH) analogues for pituitary suppression in assisted reproduction. The primary outcome was live birth rate per woman. Secondary outcomes were live birth or ongoing pregnancy per woman and per embryo transfer, ongoing pregnancy, clinical pregnancy, numbers of oocytes and metaphase-two oocytes, duration of stimulation and gonadotrophin consumption. Adverse events included miscarriage, ectopic pregnancy and multiple pregnancy rates. The GRADE system was used to assess the quality of evidence. Seven studies involving a total of 2047 women were included. Three studies compared a progestin with a GnRH antagonist and four studies compared a progestin with a GnRH agonist. Most studies are non-randomized and report outcomes per embryo transfer, rather than per woman. Although progestins were similar to GnRH antagonists in effectiveness and safety parameters, they were associated with significantly higher live birth or ongoing pregnancy per embryo transfer compared with the short GnRH agonist protocol (RR 1.49, 95% CI 1.16 to 1.91). Progestin primed stimulation lasted significantly longer (mean difference 0.61 days, 95% CI 0.33 to 0.89) and required significantly more gonadotrophins (mean difference 433.2 IU, 95% CI 311.11 to 555.19) than the short GnRH agonist protocol, but the differences were clinically negligible. Safety parameters were similar between progestins and GnRH agonists. In conclusion, progestins can effectively prevent premature ovulation in assisted reproductive technology cycles. If larger and well-designed studies confirm these findings, progestins may be an effective and low-cost alternative to GnRH analogues when a fresh embryo transfer is not planned owing to a medical indication.