title: Contraceptive efficacy of once-weekly oral administration of 2.5 mg R 2323.
mesh_terms: D000284:Administration, Oral; D000328:Adult; D003267:Contraception; D003692:Delayed-Action Preparations; D004341:Drug Evaluation; D004717:Endometrium / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D008599:Menstruation Disturbances / Q000139:chemically induced; D009645:Norgestrienone / Q000008:administration & dosage* / Q000009:adverse effects / Q000031:analogs & derivatives; D009651:Norpregnatrienes / Q000008:administration & dosage*; D011247:Pregnancy
chemical_list: D003692:Delayed-Action Preparations; D009651:Norpregnatrienes; D009645:Norgestrienone