Inclusion criteria:  Women age of 18 - 42 years Interested in the use of ESI Accepting to have 90 days pre-treatment with OD Signed informed consent  Exclusion criteria:  Pregnancy Lactation, vaginal bleeding of unknown origin, wish to become pregnant, weight over 80 kg, history of deep vein thrombosis/Pulmanory embolism, hypertension, Diabetes or other metabolic diseases, coagulation disorders, severe hepatic disorder, history of breast/endometrial cancer, known hypersensitivity to study drug, current treatment with enzyme inducing drugs (e.g.: phenytoin, carbamazepine, phenobarbital, etc.)