Evaluation of the contraceptive efficacy of quingestanol acetate.

646 patients 80% of whom were postpartum received W4540 (300 mcg) daily for a total of 6201 treatment cycles with an average duration of treatment of 9.6 cycles. 53 patients completed 12 and 5 patients completed 24 continuous cycles of treatment. 16 pregnancies resulted an overall rate of 3.1/100 woman-years. 7 pregnancies were drug failures resulting in a rate of 1.4/100 woman-years. Cycle length duration and amount of flow were consistent with normal menstrual cycles. 80% of patients had postpartum amenorrhea which lasted for an average of 2.5 months (77 days) after delivery. Intermenstrual bleeding was experienced by 35% of the patients in 7% of the cycles. Except for headache (8% of patients 2% of cycles) no significant side effects were experienced. W4540 in a dose of 300 mcg taken daily without interruption is an effective and clinically safe oral contraceptive for postpartum patients. (FULL TEXT)