Effects of Low Luteinizing Hormone Serum Levels on Oocyte Retrieval, Fertilization Rate, and Embryo Quality during Controlled Ovarian Stimulation: Results from a Prospective Cohort Analysis

Objectives: Luteinizing hormone (LH) plays a key role in normal follicular development and oocyte maturation in controlled ovarian stimulation. LH stimulates the proliferation and differentiation of theca cells for the secretion of androgens, synergistically increasing estrogen production. This study aimed to investigate the effects of low LH concentrations on oocyte retrieval, fertilization, and embryo development in patients undergoing in vitro fertilization/ intracytoplasmic sperm injection. Design: We prospectively (ClinicalTrials ID: NCT05755529) analyzed patients undergoing in vitro fertilization/intracytoplasmic sperm injection, subdividing them into three groups according to their age. Serum LH levels were evaluated on day 3, during stimulation (day 10) and before ovulation induction (day 12). Participants/Materials, Setting, Methods: Forty-three consecutive women were scheduled for IVF and received ovarian stimulation with follitropin alfa (Gonal F, Merck Serono, Germany) and ganirelix (Fyremaldel, Sun Pharma, Italy). Statistical analysis was performed with InStat 3.10, GraphPad software, San Diego, CA, USA. Normal distribution was tested by the Shapiro-Wilk test. Continuous variables were expressed as the mean and standard deviation. Categorical variables are expressed as frequencies and percentages. Results: Our data analysis suggests that serum LH levels progressively decrease during controlled ovarian stimulation, and this effect is more evident in the early phase of this procedure. From this perspective, circulating LH levels may significantly decrease during the late follicular phase due to the negative feedback of ovarian hormones from multiple follicular developments or after the suppressive effects of gonadotropin-releasing hormone antagonists. Limitations: Although our study confirms that exogenous LH can be considered a strategy in women with reduced LH levels during ovarian stimulation to improve oocyte quality and reproductive outcome, the generalizability of the results is limited by the low number of participants enrolled. Conclusions: Exogenous LH may be considered a strategy in women with a decrease in LH levels during ovarian stimulation to improve oocyte quality and reproductive outcome.