TIMING OF ONSET OF CONTRACEPTIVE EFFECTIVENESS IN DEPO-PROVERA USERS - II - EFFECTS ON OVARIAN-FUNCTION

Objective: To determine the timing of onset of contraceptive effective ness after the first injection of 150 mg of depot medroxyprogesterone acetate (DMPA) administered between days 8 and 13 of the menstrual cyc le. Design: Descriptive, prospective study. Setting: A tertiary univer sity referral center. Patient(s): Thirty healthy women between 18 and 40 years of age. Intervention: Volunteers were injected with DMPA betw een days 8 and 13 (5 women on each day) of the menstrual cycle. Main O utcome Measure(s): Ovarian function determined by serum levels of E-2 and progesterone and follicular development evaluated by vaginal ultra sound. Result(s): In nine (30%) of 30 women studied, DMPA did not prev ent ovulation. All ovulations occurred in women receiving DMPA between days 10 and 13 of the cycle. No woman who received injections on day 8 or 9 ovulated. Ovulation suppression was more effective in women wit h low ovarian activity. All ovulation occurred within 3 days after the injection. Conclusion: A back-up contraceptive method, used after the 7th day of the menstrual cycle, is recommended for up to 7 days after the first injection of DMPA. (Fertil Steril(R) 1998;70:817-20. (C) 19 98 by American Society for Reproductive Medicine.).