The role of luteinizing hormone activity in controlled ovarian stimulation for assisted reproductive technologies

Luteinizing hormone (LH) activity plays a key role in regulating folliculogenesis, ovulation, and luteinization by determining the effectiveness of controlled ovarian stimulation (COS) protocols in assisted reproductive technologies (ART). LH stimulates androgen synthesis in theca cells serving as a platform for estrogen production in granulosa cells driven by follicle-stimulating hormone (FSH), and regulates receptor expression, oocyte meiotic maturation, and luteal phase formation. Current evidence indicates that a balanced combination of FSH and LH activity is essential for optimal follicular growth and full oocyte maturation. LH deficiency leads to decreased estradiol production, impaired steroidogenesis, and reduced fertilization outcomes. The addition of active LH-containing supplements improves treatment efficacy in women with hypogonadotropic hypogonadism, diminished ovarian reserve, ovarian hyporesponsiveness, as well as in older reproductive-age patients and those undergoing gonadotropin-releasing hormone antagonist protocols. The use of human menopausal gonadotropin and its highly purified form, as well as recombinant LH, enhances hormonal balance, improves oocyte and embryo quality, and reduces the risk of ovarian hyperstimulation syndrome. Incorporation of LH activity into COS regimens supports more physiological follicular maturation and a balanced steroid response. Optimization of LH dosing and timing, along with personalized therapy based on patient age, ovarian reserve, and genetic characteristics, increases ART efficacy, improves treatment outcomes, and ensures a safer and more predictable reproductive result.