What is Femara – Letrozole?
Femara (generic name is letrozole) is an oral drug which can be an effective fertility treatment for women with ovulation problems, or for those with unexplained infertility.
This medication is in a class of drug called aromatase inhibitors. Femara has mainly been used to treat certain cases of breast cancer.
- This page is about the use of Femara for infertility
How are Femara and Letrozole Used as a Fertility Drug?
Femara to Induce Ovulation
When the enzyme aromatase is inhibited by the letrozole medication, estrogen levels are suppressed in young women. This results in the brain and pituitary gland increasing the output of FSH (follicle stimulating hormone).
In women that have polycystic ovary syndrome or anovulation (a problem with ovulation) the increase in FSH hormone can result in development of a mature follicle in the ovary and ovulation of an egg. Doctors call this process “induction of ovulation”.
Femara to Increase Pregnancy Chances in Ovulating Women
In women that already ovulate on their own, treatment with Femara can result in development of multiple follicles and multiple eggs releasing.
- Release of multiple eggs can increase the chances for pregnancy as compared to release of a single egg with a natural menstrual cycle
- Doctors refer to the process of stimulating ovulation of multiple follicles and eggs as superovulation, or controlled ovarian hyperstimulation.
Femara to Treat Infertility After Clomid Attempts Fail – Femara vs. Clomid
Clomid (brand name) or clomiphene citrate (generic name) is an oral medication that is often used for stimulating ovulation in women that do not ovulate on their own. Femara has sometimes been used in these women as an alternative to clomiphene.
- Some women will not respond to Clomid at all.
- Letrozole can induce ovulation in some of these women.
- Women that do ovulate with Clomid still might never get pregnant with it.
- Some of these women will conceive with letrozole
- There can be unpleasant side effects with Clomid that cause women to stop taking it
- This can be a reason to use Femara instead of Clomid
Femara and Pregnancy – Success Rates Using Femara and Letrozole
Monthly chances for getting pregnant using letrozole are about the same as with using Clomid.
Much will depend on the age of the female partner and on the status of the fallopian tubes and the male’s sperm quality.
Higher Success for Women Not Ovulating on Their Own
With the following conditions, we can expect approximately 15% per month for a chance to get pregnant with Femara:
- No other fertility issues are present
- The female partner is under 35 years old
- We achieve ovulation with the letrozole in a woman that was not ovulating
Lower Success for Unexplained Fertility in Ovulating Women
When it is being used for unexplained infertility in a woman who ovulates regularly on her own, the expectations for success are significantly lower than that.
Femara and IUI
Whether it is being used in unexplained infertility, or to induce ovulation, adding intrauterine insemination (IUI) and Femara together significantly improves chances for pregnancy.
Femara and Letrozole Dosing
- The most common dose of Femara is 2.5 mg per day on days five through nine of the menstrual cycle
- Sometimes it is given in higher doses of 5 mg or 7.5 mg per day
Risks and Side Effects of Femara
Report on Higher Incidence of Birth Defects
Many physicians will not prescribe letrozole because of concerns from a 2005 report from some Canadian fertility doctors suggesting a possible higher incidence of birth defects in pregnancies from using letrozole.
- This study was from a small group of pregnancies and the study has been severely criticized for having an improper design
- Femara is known to have a short half-life in the bloodstream and is given early in the menstrual cycle – several days before a fertilized embryo is present.
- It is believed that the drug has cleared from the system before the egg is fertilized. Therefore, it is puzzling as to how the drug could cause birth defects.
- The manufacturer of letrozole sent a warning to doctors saying there are reported birth defects in children born after mothers took Femara. This may have been due to liability concerns (lawyers and financial risks for a drug company) rather than real science.
- The manufacturer of the drug has apparently not filed for FDA approval to use it for infertility. However, physicians often use medications in an “off label” way. When the off label use is safe and effective it is perfectly legitimate.
Is Femara Prescribed by Fertility Specialists?
- Some fertility specialists or gynecologists will not prescribe Femara
- Others will use it – after explaining to the patient that there has been concerns raised regarding the potential for increased rates of birth defects
