Abstract
To evaluate the decrease in luteinizing hormone (LH) levels following gonadotropin-releasing hormone (GnRH) antagonist administration in in vitro fertilization (IVF) cycles, data were retrospectively collected from 305 consecutive IVF or intracytoplasmic sperm injection (ICSI) cycles of patients who underwent ovarian stimulation with gonadotropins and were treated with GnRH antagonist for the prevention of premature luteinization. We compared the percent change in LH concentration from stimulation start to that observed before ovulation triggering in patients with or without anovulation. Anovulatory patients were younger, with higher body mass index (BMI), and demonstrated higher ovarian reserve parameters as compared to ovulatory patients. The decline in LH concentration was almost two-fold greater in anovulatory versus ovulatory patients. Numbers of oocytes, fertilizations, cleavage stage embryos, and transferred embryos were similar; however, implantation rates were higher in anovulatory versus ovulatory patients. Older patients (age ≥39) showed a smaller decline in LH levels as compared to younger ones (age <39) and exhibited poor IVF outcomes. There is a wide range of pituitary responses to GnRH antagonists. Anovulatory patients are more susceptible to GnRH antagonists and therefore demonstrate over-suppression of the pituitary. Older patients demonstrate a reduced pituitary response to GnRH antagonists than younger ones. Cycle scheduling with estradiol pretreatment did not influence LH decline, nor IVF treatment outcomes.