OBJECTIVE To elucidate the physiologic mechanism responsible for the supraphysiologic gonadotropin release from the pituitary induced by gonadotropin-releasing hormone (GnRH) agonist in female rats primed with GnRH antagonist. DESIGN Controlled experimental intervention. SETTING Government research facility. ANIMAL(S) Forty 8-week-old Sprague-Dawley rats. INTERVENTION(S) Forty oophorect...

OBJECTIVE To assess whether an early GnRH antagonist start leads to better follicular synchronization and an improved clinical pregnancy rate (CPR). METHODS A retrospective cohort study. A total of 218 infertile women who underwent IVF between January 2011 and February 2013. The initial cohort (Cohort I) that underwent IVF between January 2011 and March 2012 included a total of 68 attempted I...

background: gonadotropin-releasing hormone (gnrh) plays essential roles in embryo implantation, invasion of trophoblastic tissue, and steroid synthesis in the placenta. objective: the aim of this study was to evaluate the effect of gnrh antagonist administration on pregnancy outcomes in early implantation period. materials and methods: in this retrospective study, 94 infertile women undergoing ...

We believe that appropriate comparison of optimal GnRH agonist and antagonist regimens has not been performed yet. Currently available meta-analyses included all comparative studies between GnRH agonists and antagonists performed so far, including less than optimal GnRH antagonist regimens. After critical appraisal of the various studied GnRH antagonist regimens in terms of follicular developme...

In an attempt to examine whether body mass index (BMI) may influence IVF outcome in patients undergoing COH with either GnRH-agonist (agonist group) or GnRH-antagonist (antagonist group), we studied 799 IVF cycles: 481 in the agonist group and 318 in the antagonist group. In patients with BMI >25 kg/m(2), COH with either GnRH-agonist or GnRH-antagonist achieved a comparable outcome; whereas in ...

The reports on how to stimulate the ovaries for oocyte retrieval in good prognosis patients are contradictory and often favor one type of controlled ovarian hyperstimulation (COH). For this reason, we retrospectively analyzed data from IVF/ICSI cycles carried out at our IVF Unit in good prognosis patients (aged <38 years, first and second attempts of IVF/ICSI, more than 3 oocytes retrieved) to ...

OBJECTIVE To compare the outcomes of protocols for ovarian stimulation with recombinant hCG microdose, with GnRH agonists and antagonists for pituitary suppression. DESIGN Prospective nonrandomized clinical trial. SETTING A private assisted reproduction center. PATIENT(S) We studied 182 patients undergoing intracytoplasmic sperm injection (ICSI) cycles, allocated into two groups: GnRH ago...

BACKGROUND GnRH agonist was recently suggested as a novel luteal-phase support that may act at different levels, including the pituitary gonadotrophs, the endometrium and the embryo itself. This prospective randomized study evaluates the effect of GnRH agonist administered in the luteal phase on ICSI outcomes in both GnRH agonist- and GnRH antagonist-treated ovarian stimulation protocols. MET...

Previous studies have established the presence of an extrahypothalamic GnRH in a variety of tissues. GnRH receptor is known to be present in the placenta, which produces and secretes the decapeptide from the very early stages of placentation. We hypothesized that GnRH may play a role in the preimplantation development of embryos. To examine this hypothesis, we assessed GnRH and GnRH receptor me...

BACKGROUND In order to investigate whether gonadotrophin-releasing hormone (GnRH) antagonists exert a significant effect on steroid secretion in vivo compared with GnRH agonists, concentrations of sex steroid hormones (oestradiol, progesterone and testosterone) were studied in follicular fluid from women undergoing ovarian stimulation and treated with either GnRH agonist or antagonist. In addit...