The use of anti-breast cancer drugs letrozole (Letoval) and tamoxifen (Oncomex) is contraindicated (not permitted) in pre-menopausal women (i.e. during child bearing age) the world over. Both the Canadian Government Drug Controller and the innovator company, Novartis, have warned gynaecologists the world over not to use letrozole for female infertility. Research on 150 pregnancies has shown that babies born to mothers who had consumed letrozole to increase fertility have suffered from bone malformations, cardiac stenosis and cancers. Fortunately, these drugs do not leave any trace in the body and hence would not cause any adverse effects in future.