Diethylstilbestrol drug molecule, molecular model. This drug is a synthetic nonsteroidal oestrogen first approved for medical use in the USA in 1941. It was used to treat post-menopausal symptoms, vaginitis (inflammation of the vaginal mucosa), prostate and advanced breast cancer. It was also thought to prevent miscarriages. However, it was found to be a teratogen, causing congenital defects when prescribed to pregnant women. Manufacture of the drug ceased in 1997. In this model, atoms are represented by coloured spheres; carbon is green, hydrogen is white and oxygen is red.