Blood Coagulation Factors/drug effects; Contraceptives, Oral, Synthetic/pharmacology; Menstruation/drug effects; Norethindrone/analogs & derivatives; Adult; Amenorrhea/chemically induced; Antigens/analysis; Antithrombin III/analysis; Contraceptives, Oral, Synthetic/administration & dosage; Contraceptives, Oral, Synthetic/adverse effects; Delayed-Action Preparations; Erythrocyte Count/drug effects; Erythrocyte Volume/drug effects; Factor VII/analysis; Factor VII/immunology; Factor X/analysis; Female; Hemoglobins/analysis; Humans; Injections; Middle Aged; Norethindrone/administration & dosage; Norethindrone/adverse effects; Norethindrone/pharmacology; Time Factors

Amenorrhea; Biology; Blood Coagulation Effects; Comparative Studies; Contraception; Contraceptive Agents, Female--administraction and dosage; Contraceptive Agents, Progestin--administraction and dosage; Contraceptive Agents--administraction and dosage; Contraceptive Methods; Contraceptive Usage; Control Groups; Developed Countries; Diseases; Europe; Examinations And Diagnoses; Family Planning; Hematological Effects; Hemic System; Hemoglobin Level--analysis; Incidence; Injectables; Laboratory Examinations And Diagnoses; Measurement; Menstrual Cycle--changes; Menstruation; Menstruation Disorders; Method Acceptability; Norethindrone Enanthate--administraction and dosage; Norethindrone--administraction and dosage; Northern Europe; Physiology; Reproduction; Research Methodology; Studies; United Kingdom