Inclusion Criteria:

• Signed and dated informed consent
• Healthy female volunteers
• Age: 18 - 35 years (inclusive), smokers must not be older than 30 years at inclusion
• History of regular cyclic menstrual periods (with a cycle length between 25 and 35 days)
• Willingness to use barrier methods of contraception (condoms with spermicide, diaphragms with spermicide, spermicidal vaginal suppositories) or abstinence during the trial

Exclusion Criteria:

• Pregnancy, lactation (less than three menstrual cycles before Visit 1 following delivery, abortion, or lactation)
• Obesity (BMI > 30.0 kg/m2)

• Abnormal, suspicious or unclear cervical smear (a cervical smear has to be taken at Visit

  1 or a normal result has to be documented within the last 6 months before Visit 1)

• Laboratory values outside inclusion range at Screening
• Any disease that may worsen under hormonal treatment or might interfere with the conduct of the study or the interpretation of the results, as e.g.:
• Cardiovascular
• presence or a history of venous or arterial thrombotic/thromboembolic events (e.g., deep venous thrombosis, pulmonary embolism, myocardial infarction) or of a cerebrovascular accident, including prodromi (e.g., transient ischemic attack, angina pectoris) and conditions which could increase the risk to suffer from any of the above mentioned disorders, e.g., a family history indicating a hereditary predisposition. uncontrolled arterial hypertension (repeated measurements of systolic blood pressure > 140 mmHg and/or diastolic blood pressure > 90 mmHg)
• Liver presence or history of liver tumors (benign or malignant) presence or history of severe hepatic disease as long as liver function values have not returned to normal jaundice and/or pruritus related to cholestasis history of cholestatic jaundice associated with pregnancy or previous COC use
• Metabolic diseases uncontrolled diabetes mellitus with vascular involvement severe dyslipoproteinemia
• Other diseases any known or suspected malignant or premalignant disease, uncontrolled thyroid disorder, chronic inflammatory bowel disease, severe renal insufficiency or acute renal failure, hemolytic uremic syndrome, sickle cell anemia, porphyria, history of hypertriglyceridemia-associated Pancreatitis, systemic lupus erythematodes, pemphigoid gestationis during a previous pregnancy, Sydenham chorea, herpes gestationis, otosclerosis-related hearing loss, history of migraine with focal neurologic symptoms, epilepsy, current or history of clinically significant depression, hereditary angioedema
• Additional sex steroids, other hormonal contraceptive methods (oral, transdermal) during treatment (blister in use at randomization should be finished); intra-uterine devices (IUD) with or without hormone release within 1 month prior to Visit 1, implants within 1 month prior Visit 1, depot progestins within 6 months prior to Visit 1
• Surgical interventions scheduled in the study period