Letrozole is an oral medication used in fertility treatments to help individuals achieve pregnancy. While initially developed for breast cancer therapy, its ability to influence hormone levels has made it valuable in reproductive medicine. This medication is primarily associated with stimulating ovulation. This article explores how letrozole works and whether it improves egg quality.
Letrozole’s Mechanism in Ovulation
Letrozole functions as an aromatase inhibitor, temporarily blocking the enzyme that converts androgens into estrogen within the body. This inhibition leads to a reduction in estrogen levels. The body interprets this drop in estrogen as a signal that more estrogen is needed.
In response, the pituitary gland in the brain increases its production of Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH). FSH stimulates the ovaries to develop and mature follicles, which are small sacs containing immature eggs. Increased FSH promotes the growth of these ovarian follicles, making it more likely for an egg to mature.
As follicles grow, they naturally produce estrogen. When estrogen levels reach a certain threshold, the brain signals a surge in LH, which triggers the final maturation and release of a mature egg from the ovary. This mechanism is particularly useful for individuals who do not ovulate regularly, such as those with polycystic ovary syndrome (PCOS).
Impact on Egg Quality
Egg quality refers to the genetic and cellular health of an egg, its ability to be fertilized, develop into a healthy embryo, and lead to a successful pregnancy. A high-quality egg possesses the correct number of chromosomes. Letrozole does not directly alter an egg’s intrinsic genetic quality; once an egg is genetically abnormal, it cannot be made normal.
Letrozole indirectly supports egg quality outcomes by optimizing the environment for existing eggs. By promoting the growth and maturation of follicles, it increases the chances of releasing a mature and potentially healthier egg. This is beneficial for individuals with irregular ovulation, as it helps them achieve regular cycles where a viable egg can be selected and developed.
Letrozole also creates a favorable follicular environment. Temporary changes in the follicular fluid, such as increased androgen levels due to aromatase inhibition, can enhance the sensitivity of follicles to FSH, further aiding their development. For individuals with ovulatory disorders like PCOS, letrozole can induce ovulation, increasing the opportunity for a good quality egg to mature and be released. This controlled stimulation allows for better selection and development of the best available egg, even if it doesn’t improve the egg’s inherent genetic makeup.
Important Considerations
Letrozole is a prescription medication and requires healthcare professional supervision. It is taken orally for five days, typically starting early in the menstrual cycle (days two to five). The starting dosage is 2.5 mg once daily, adjustable up to 7.5 mg.
Common side effects are mild and temporary, resembling menopausal symptoms due to temporary estrogen reduction. These include hot flashes, fatigue, headaches, and dizziness. Serious side effects are rare, but patients should report concerning symptoms like blurred vision or severe pain.
Medical monitoring, including ultrasounds and blood tests, is important during letrozole treatment. This monitoring tracks follicular development, assesses the uterine lining, and helps prevent complications like ovarian hyperstimulation syndrome (OHSS), which is less common with letrozole. Letrozole is often integrated into a broader fertility treatment plan, which may include timed intercourse or intrauterine insemination (IUI).