title: A report of a collaborative dose-response clinical study using decreasing doses of combination oral contraceptives.
mesh_terms: D000328:Adult; D000568:Amenorrhea / Q000139:chemically induced; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004997:Ethinyl Estradiol / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D006801:Humans; D008599:Menstruation Disturbances / Q000139:chemically induced; D009640:Norethindrone / Q000008:administration & dosage* / Q000009:adverse effects; D011247:Pregnancy
chemical_list: D004338:Drug Combinations; D004997:Ethinyl Estradiol; D009640:Norethindrone