The purpose of this research study is to gain a better understanding of the changes that may occur in the breast when a woman uses an oral contraceptive (birth control pill). Some research indicates that women who use birth control pills with lower amounts of progestin (a hormone in the birth control pill) may have lower breast cell growth than women who use birth control pills with a higher amount of progestin; this research will examine that in detail.

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.

Adverse events were collected beginning day 1 of study and continued throughout the study until 30 days after the last dose.