Answer:
It has been used for ovarian stimulation by fertility doctors since 2001; having less side-effects than clomiphene citrate (Clomid) for the patient and may be it possess less risk for multiple gestation. A Canadian study presented at the American Society of Reproductive Medicine 2005 Conference suggests that it may increase the risk of birth defects compared with a control group, however a more detailed follow-up study found no basis for concern when letrozole is used for ovulation induction. The manufacturer, Novartis, has issued letters to doctors in Canada and the United States reiterating that it is not approved for such a use and is not safe to use with pregnant women or women who may become pregnant.