Daily progestogen for contraception: a clinical study.

Chlormadinone acetate 1 tablet (.5 mg) daily was given without interruption to 2 groups of fertile women 945 non-lactating and 100 lactating for a total of 8652 months. Conception was successfully prevented without inhibiting ovulation and with endogenous hormonal control of cycle bleeding. The pregnancy rate adjusted for patient failures was .2 in the group of non-lactating women. The use-effectiveness pregnancy rate was 2.1. In distribution menstrual cycle length in the non-lactating group from cycle to cycle was relatively constant. Between 60% and 74% of the women for any given month had a cycle length of 25-35 days. There were no pregnancies in the lactating group. Chlormadinone acetate was not found to interfere with nursing needs. Other than bleeding irregularies which may be overcome by using still lower dosages chlormadinone acetate was found to be remarkably benign.(AUTHORS MODIFIED)