Impact of GnRH ovarian stimulation protocols on intracytoplasmic sperm injection outcomes

Although a large number of studies have been conducted in relation to ovarian response and pregnancy after GnRH agonist and GnRH antagonist controlled ovarian hyperstimulation protocols, most of them used single or combinations of a few predictive factors, and none included the stimulation protocol in the multivariable analysis. The present study was thus primarily designed to investigate the predictive value of the stimulation protocol and to analyze the possible relationships between stimulation protocols and treatment outcomes after adjusting for a large set of variables that potentially affect reproductive outcomes. Factors related to pregnancy achievement and predictive of the number of oocytes retrieved and high quality of the embryos obtained were also analyzed.

To analyze the impact of GnRH ovarian stimulation protocols on the independent predictors of ovarian response, high quality embryos and clinical pregnancy, two groups out of 278 ICSI treatment cycles were compared prospectively, 123 with a GnRH agonist and 155 with a GnRH antagonist, with multivariable analysis assessing outcomes after adjusting for a large set of variables.

Antagonists were significantly associated with lower length and total dose of GnRH, lower length of rFSH, and higher numbers of oocytes and high quality embryos, whereas the agonist presented a higher fertilization rate and probability of pregnancy. Significant predictors of retrieved oocytes and high quality embryos were the antagonist protocol, lower female age, lower serum levels of basal FSH and higher total number of antral follicles. Significant predictors of clinical pregnancy were the agonist protocol, reduced number of attempts, increased endometrial thickness and lower female age. The probability of pregnancy increased until 30 years-old, with a decline after that age and with a sharp decline after 40 years-old.

The models found suggest that not only the protocol but also factors as female age, basal FSH, antral follicles, number of attempts and endometrial thickness should be analyzed for counselling patients undergoing an ICSI treatment.