Letrozole is an oral medication, which induces ovulation by blocking the conversion of testosterone into estrogen. This will, in effect, increase the brain production of follicle and luteinizing hormones and send a message to the ovary to increase the growth of the follicles (eggs). Letrozole is a medication we often use to increase the ovulation rate or improve ovulation in women who are already ovulating. Letrozole was found to be superior to clomid when inducting ovulation in patients with the diagnosis of Polycystic ovarian syndrome. Unlike clomid, letrozole does not have the same side effects of thinning the uterine lining or decreasing the cervical mucous.
Letrozole Side Effects:
Most women experience no side effects. However, if you have any of the following symptoms listed below, call our office at (713) 467-4488 extension 4.
- Ovarian enlargement associated with abdominal discomfort
- Hot flashes
- Abdominal bloating
- Pain in your side
- Blurred vision
The multiple pregnancy rate is not well studied but it should be similar to clomid’s 5-10%.
Letrozole in combination with gonadotropins injections
In patients who have previously used letrozole or have a history of low ovarian reserve, we may elect to use letrozole in combination of injectable medications. The combination typically has a higher pregnancy rate (up to 35%) and the risk of twins is about 25%. The injectable medications known as Gonal-F and Follistim are synthetic forms of Follicle Stimulating Hormone. Menapur is a combination of Follicle Stimulating Hormone and Luteinizing Hormone. The added advantage of these injections is counteracting the side effects of letrozole while increasing the estrogen levels and the number of follicles growing. Letrozole is initiated on day 3-7 and the injections are added on day 6. A pelvic ultrasound is typically done on day 10 to carefully monitor the size of the follicles. Once the follicles reach maturation, an injection of hCG is given to induce ovulation. We can also combine letrozole with gonadotropins and an intrauterine insemination (IUI), which is typically done 24-36 hours after the hCG injection.
Injectable Medication Side Effects:
These injectable medications are potent drugs with potential side effects. You may experience:
Ovarian Hyperstimulation Syndrome is a rare risk, which leads to ovarian enlargement, abdominal distention, and difficulty breathing. This can occur in 2% of patients and unfortunately is not preventable. If you gain more than 2 lbs. daily and are unable to void, you must notify our office immediately. At AFCT, every effort is taken to prevent this risk.
Intrauterine insemination (IUI) is a common infertility treatment procedure and may be an option for couples experiencing unexplained fertility, ovulation disorders, and mild-to-moderate male factor infertility. It is used as a first-line infertility treatment and is easily performed in the office. It can be used in combination with Clomiphene, Letrozole, or the combination of letrozole, clomid with follicle-stimulating hormone (FSH), and luteinizing hormone (LH). The chance of pregnancy with IUI is about 5% higher than with other medications used alone in that cycle. Patients planning to have an IUI often undergo ovulation induction with oral medications or a combination of oral medications and gonadotropins injections at the same time to increase their chances of conception. Ovulation induction, also referred to as controlled ovarian hyperstimulation (COH), increases the chances of pregnancy by allowing the development of multiple eggs during a patient’s menstrual cycle. This increases the chance of pregnancy by releasing more eggs that the sperm can fertilize.
Ovulation induction can be achieved by taking oral medications such as Clomiphene citrate (Clomid) or Letrozole, or by using injectable medications containing FSH or LH (e.g., Gonal-F, Follistim, Menopur). Once the eggs are determined to be mature by ultrasound or laboratory tests, an injection of human chorionic gonadotropin (hCG) is usually given. The hCG injection results in the release of the eggs into the fallopian tubes where they can be fertilized.
The IUI procedure is usually scheduled 24-36 hours after the hCG injection. Two hours prior to the IUI, the male’s sperm is obtained, washed, and concentrated. When the sperm sample is ready, a very small catheter is passed through the cervix and the sperm is introduced into uterus with minimal discomfort and no sedation.
The Advanced Fertility Center of Texas (AFCT) has several fertility treatment centers located throughout Houston metropolitan area. We offer the most comprehensive list of state-of-the-art fertility services.