Can femara (letrozole) cause a miscarriage?

Danger to fetus: Femara (letrozole) is used to treat breast cancer in women who have gone through menopause. It should not be used in women who are or will become pregnant. It has a category x rating which means that it is contraindicated during pregnancy as animal studies have shown toxicity to the developing embryo (baby). It acts to decrease the level of estrogen and that might lead to miscarriage.

Should not: Femara (letrozole) is only recommended for post-menopausal women. So, if a woman has not entered menopause yet, she should not take femara (letrozole). Pre-menopausal women usually take tamoxifen, which will often cause a disruption in their menstrual cycles, so getting pregnant is less likely. However, women are not recommended to get pregnant while on tamoxifen.