Depot Medroxyprogesterone Acetate as Emergency Contraception

The proposed study will enroll 36 healthy, non-pregnant, non-breastfeeding, reproductive age women with regular ovulatory cycles. Potential participants will undergo screening, which will include a history, physical exam, assessment of vital signs, and blood draw for assessment of ovulation via mid-luteal progesterone levels. If her progesterone level confirms ovulatory status (\> 3 ng/ml), she will be offered enrollment and assigned to one of three follicular phase groups based on her leading follicle size in the next cycle: 12-14 mm, 15-17 mm, and ≥18 mm. To determine follicle size, participants will receive serial transvaginal ultrasound (TVUS) scans of their ovarian follicles starting on cycle day 8 of the next menstrual cycle. The scans will be performed three times weekly to identify her leading follicle. Once the leading follicle has reached its assigned size, DMPA will be administered. Blood samples will be obtained prior to administration for baseline hormonal assays. One hour after administration, blood will be drawn for MPA levels. For the following five consecutive days, the participant will undergo daily TVUS to detect signs of follicular rupture and blood draws to assess serum markers of ovulation (estradiol, progesterone, and luteinizing hormone). On the first day, 24 hours after DMPA administration, blood will be drawn for MPA levels as well. After five days, the participant will return twice weekly for two weeks to provide serum progesterone levels to detect any delayed ovulation or ovulatory dysfunction. At the final visit, she will fill out a simple survey to assess her satisfaction with DMPA as an EC method, and whether she would recommend this method to others.