Background:

The prevalence of repeat unprotected intercourse after EC use in the same cycle demonstrate the need for more self-bridging emergency contraceptive options. We propose the use of intramuscular Depot Medroxyprogesterone acetate (DMPA) as EC, which has been shown to inhibit follicular activity within 24 hours, and provide on-going contraception via suppression or disruption of ovulation.

Objective:

The objective of this study is to explore the potential of depot medroxyprogesterone acetate (DMPA) given as a 150-mg intramuscular injection for use as an emergency contraceptive.

Study population:

Healthy regularly menstruating women aged 18-39 years old will be invited to participate if they fulfill inclusion criteria. The participants will undergo a screening visit during the midluteal phase of their cycle, and will be enrolled if a serum progesterone level is >3ng/ml.

Methodology:

Participants will be assigned to one of three groups based on leading follicle size. Starting cycle Day 8, transvaginal ultrasounds will be performed to assess the size of the leading follicle. Once the follicle has reached the pre-assigned size, 150 mg IM DMPA will be administered. Blood will be collected for baseline hormonal assays. For 5 consecutive days, daily blood will be drawn for hormonal assays and daily transvaginal ultrasound will be performed to assess for signs of ovulation. The participant will then return for twice weekly progesterone levels for 2 weeks for study completion.

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.

Inclusion Criteria:

• Healthy women of reproductive age (18-39 years old) with BMI 18-30 kg/m2
• Regular menses for the last 3 months
• Cycle duration 24 to 35 days
• Women using copper IUD, sterilization, or barrier methods as current or preferred birth control method, and women reporting exclusive sex with women
• English- or Spanish-speaking

Exclusion Criteria:

• Any contraindications to progesterone contraception per teh CDC Medical Eligibility Criteria (Category 3 or 4)
• On medications that can alter, or be altered by, progesterone contraceptive steroid hormone (e.g., aminoglutethimide or other anti-steroid medication)
• Use of any hormonal contraceptive pill, patch, or vaginal ring in the month prior to recruitment
• Use of depot-medroxyprogesterone acetate in teh 10 months prior to recruitment
• Currently pregnant and/or breastfeeding
• History of allergic reaction to depot medroxyprogesterone acetate (rash, urticaria, anaphylaxis)