Clinical experience with intramuscular norethisterone oenanthate as a contraceptive

SummaryA contraceptive, norethisterone oenanthate 200 mg given by intramuscular injection at intervals mostly of 70 days, was studied during 3503 woman-months of clinical use. The life-table failure rate was 1·3 per 100 woman-years. Bleeding was in all cases irregular. A small group of subjects, comprising 6 per cent of the total, experienced 68·5 per cent of the episodes of amenorrhoea lasting more than 70 days.Irregular bleeding was the major cause of discontinuation and other side effects were trivial. There was no tendency for either body weight or blood pressure to rise. The continuation rate was 63·6 per cent.Norethisterone oenanthate 200 mg is safe and effective and, despite imperfect cycle control, is a useful contraceptive method.