Pharmacodynamics and Pharmacokinetics Study of Existing DMPA Contraceptive Methods

inclusion Women may be included in the study if they meet all of the following criteria: * in good general health * age 18 to 40 years, inclusive * willing to provide informed consent and follow all study requirements * not pregnant * does not desire to become pregnant in the next 24 months * regular menstrual cycle (24 to 35 days) * confirmed ovulation by serum P ≥ 4.7 ng/mL in two consecutive samples during the pre-treatment phase of the study * at low risk of pregnancy (e.g., sterilized, in exclusively same sex partnership, in monogamous relationship with vasectomized partner, abstinent, using non-hormonal IUD or condoms) * has a body mass index of 18.0 to 35.0 * has hemoglobin ≥10.5 g/L exclusion Women will be excluded from participating in this study if they meet any of the following criteria: * medical contraindications to DMPA use * use of any of the following medications within 1 month prior to enrollment: * any investigational drug * prohibited drugs (per protocol) * oral contraceptives * LNG IUS or implant * use of DMPA in the past 12 months * use of a combined injectable contraceptive in the past 6 months * recent pregnancy (within 3 months) * current lactation * ongoing or anticipated use of prohibited drugs (per protocol) * known sensitivity to MPA * plan to move to another location in the next 18 months * any condition (social or medical) which in the opinion of the site investigator would make study participation unsafe, would interfere with adherence to study requirements or complicate data interpretation.