Gonadotrophin-releasing hormone agonist protocols for pituitary suppression in assisted reproduction

Review question Researchers from the Cochrane Collaboration reviewed the evidence about the most effective way of using gonadotrophin‐releasing hormone agonists (GnRHa) as part of controlled ovarian stimulation in women undergoing assisted reproduction technology (ART). Background GnRHa are given along with hormone injections that stimulate the ovaries, in an attempt to prevent spontaneous release of eggs prior to their planned surgical retrieval. GnRHa have been proven to improve pregnancy rates; however, various regimens are described in the literature. We conducted this review to identify the most effective regimens. Study characteristics We found 37 randomised controlled trials (RCTs) of 3872 women comparing the use of GnRHa in various protocols. Twenty of these RCTs (1643 women) compared a long protocol with a short protocol. The evidence is current to April 2015. Key results In comparisons of long GnRHa protocols (where GnRHa is given for at least 14 days prior to the start of ovarian stimulation) versus short GnRHa protocols (when the GnRHa is given at the start of stimulation) there was no conclusive evidence of a difference in live birth and ongoing pregnancy rates. However there was moderate quality evidence of higher clinical pregnancy rates in the long protocol groups. Our findings suggest that in a population in which 14% of women achieve live birth or ongoing pregnancy using a short protocol, between 13% and 23% will achieve live birth or ongoing pregnancy using a long protocol. None of the other analyses showed any evidence of a difference in birth or pregnancy outcomes between the protocols compared. There was insufficient evidence to make any conclusions regarding adverse effects. Further research is needed to determine which long protocol is most cost effective and acceptable to women. Quality of the evidence The quality of the evidence ranged from moderate to low. The main limitations in the evidence were failure to report live birth or ongoing pregnancy, poor reporting of methods in the primary studies, and imprecise findings due to lack of data. Only 10 of the 37 included studies were conducted within the last 10 years