Inclusion Criteria:  Healthy females aged 18-45 years Body-mass index ≥18.5kg/m2 Willing to abstain from medications and supplements known to induce/inhibit CYP3A4 during the study Normal blood pressure measurement at screening (systolic <140mmHg, diastolic <90mmHg) Negative urine pregnancy test at screening  Exclusion Criteria:  Currently taking any known CYP3A4 inducers/inhibitors Medical conditions that affect liver function (e.g. hepatitis, cirrhosis) Any contraindications to estrogen-containing contraception (based on any category 3 or 4 recommendations from the CDC MEC guidelines) Use of an injectable contraceptive method within the last 6 months or current use of an ENG contraceptive implant Childbirth within the last 6 months Known allergy or insensitivity to combined oral contraceptive pills