Letrozole, Femara® is a pill that can be taken to improve fertility.
Letrozole prevents the natural conversion of androgens (male hormones) to estrogen (female hormone) in a woman’s body. When this occurs, the brain and pituitary sense that there is not enough estrogen around. As a result, the pituitary releases more FSH, which signals the ovary to cause eggs to start developing. Like clomiphene, letrozole may also cause multiple follicular development to occur, although it does not tend cause multiple follicle development as often as Clomid. Drs. Munch and Hudson tend to utilize Letrozole in a few specific situations:
- When Clomid fails to cause ovulation, Letrozole may induce ovulation because it works in a different way to increase FSH production from the brain.
- When Clomid causes a thin uterine lining, Letrozole can cause ovulation without having this negative side effect.
- For women who have used Clomid unsuccessfully but are not yet ready or able to move on to injectable gonadotropins.
- When there is an over-response to Clomid (too many eggs for ovulation).
Letrozole is a medication that was actually developed as an adjunctive treatment for breast cancer. While it is NOT a chemotherapeutic drug (and will therefore not cause side effects like hair loss, nausea/vomiting, etc), it helps keep estrogen levels low. This can be beneficial in women with estrogen dependent cancers (like many breast cancers). It is the lowering of estrogen production that also makes it useful for ovulation induction.
Letrozole usually does not cause as many side effects as Clomid. However, nausea, fatigue and headaches can occur and some women also (rarely) report hot flushes.
If taken during pregnancy, Letrozole can cause birth defects. However, when taken to cause ovulation, Letrozole appears to be safe. It is metabolized before pregnancy occurs and there should therefore be no increased risk of birth defects in a pregnancy resulting from ovulation induction with Letrozole. Several years ago, a very small study suggested that letrozole could cause birth defects. As a result, Novartis (the company that makes letrozole) sent a letter to all physicians stating that letrozole should not be used in in pregnancy or in women attempting pregnancy. Later studies did not show any increased risk for fetal abnormalities and therefore most fertility specialists have continued to use letrozole. Because of this issue, however, Dr. Munch and Dr. Hudson will require a blood pregnancy test before every cycle of Letrozole treatment even if you are having a full flow.
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