Review of ovulation return upon discontinuation of once-a-month injectable contraceptives.

Once-a-month combined injectable preparations draw their contraceptive efficacy from continuous ovulation suppression. When their use is discontinued, ovulation resumes within a few weeks or a few months, depending on the formulation. After use of the dihydroxyprogesterone acetophenide 150 mg/estradiol enanthate 5 mg combination for one to two years, ovulation returns in most subjects 3-4 months after discontinuation of treatment. Similarly, recent data show that after 2-year use of the depot-medroxyprogesterone acetate 25 mg/estradiol cypionate 5 mg or the norethisterone enanthate 50 mg/estradiol valerate 5 mg combination, approximately 70% women have resumed ovulation by the third month post-treatment. This is shorter than the time for return of ovulation experienced by ex-users of progestogen-only injectable contraceptives.