Does the “delayed start” protocol with gonadotropin-releasing hormone antagonist improve the pregnancy outcome in Bologna poor responders? a randomized clinical trial

Abstract Background Recently, a novel approach with delaying the start of controlled ovarian stimulation along with gonadotropin-releasing hormone (GnRH) antagonist pretreatment for 7 days after estrogen priming for further suppression of endogenous follicle stimulating hormone (FSH) during the early follicular phase, resulting in more FSH-responsive follicles and thus improving synchronous follicular development was introduced. Two clinical trials have examined this strategy and reported controversial results. This study aimed to compare the effect of delayed-start GnRH antagonist protocol and standard GnRH antagonist in patients with poor ovarian response (POR) undergoing in vitro fertilization (IVF)/ intracytoplasmic sperm injection (ICSI). Methods This randomized clinical trial was conducted at infertility department of Royan Institute from January 2017 to June 2018. Poor ovarian response was defined according to the Bologna criteria. The eligible women were randomly allocated into an experimental and control groups. In experimental group, patients received delayed-start GnRH antagonist protocol with estrogen priming followed by early follicular-phase GnRH antagonist treatment for 7 days before ovarian stimulation with gonadotropin and in control group, patients treated with estrogen priming antagonist protocol. IVF/ICSI outcomes were compared between groups. Results Among all the 250 patients examined 156 women were eligible for study and finally 120 patients were allocated to intervention (n = 60) and control (n = 60) groups. Demographic characteristics and hormonal profiles of the patients did not differ between groups. The statistical analysis showed that there were significant differences between groups regarding the total dose of used gonadotropins (P < 0.001), stimulation duration (P < 0.001), number of retrieved oocytes (P = 0.01) and top quality embryo (P < 0.001) and also cancellation (P = 0.002) and fertilization rates (P = 0.002). Conclusion On the basis of present results the delayed-start protocol in poor responders can improve the fertilization rate and quality of embryos and reduce the cycle cancellation but have no significant effect on clinical pregnancy rate; however, larger randomized clinical trials are required to compare it with other protocols. Trial registration NCT, NCT03134690. Registered 1 May 2017 - Retrospectively registered, http://www.clinicaltrial.gov/ NCT03134690