Inclusion Criteria:

1. Age 18-34.

2. Premenopausal.

3. Currently taking or want to start oral contraceptives for contraception

4. Non-smoker.

5. Competent to give informed consent (as judged by the investigator).

6. Provided written informed consent.

7. Willingness to refrain from smoking and consumption of grapefruit or grapefruit juice
during the study (grapefruit interferes with metabolism of exogenously administered
OCs).

Exclusion Criteria:1.

1. Abnormal breast examination.

2. History or current therapeutic or prophylactic use of anticoagulants.

3. Known bleeding disorder or history of unexplained bleeding or bruising.

4. History of breast cancer or previous diagnostic breast biopsy.

5. Known allergy to local anesthetic.

6. Currently pregnant or pregnant within the previous 6 months.

7. Having any standard contra-indication to being prescribed OCs.