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

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).