Norethisterone oenanthate as an injectable contraceptive: use of a modified dose schedule.

Norethisterone oenanthate (NET-OEN) was given as an injectable contraceptive to 295 healthy women over 1606 woman-months. A modified injection schedule was used. There were no pregnancies, and the 12-month, life-table, use-related discontinuation rate was 39.1/100 users. Menstrual disturbance (10.8/100 women), minor side effects (13.5/100 women), and personal reasons (12.0/100 women) were the main causes of use-related discontinuation. There was no difference in use-related discontinuation rates between women receiving their first injection during a normal menstrual period and those receiving it immediately after a pregnancy. There were no serious side effects. The use of NET-OEN in certain groups of women is recommended, particularly in those in need of highly effective contraception, who cannot or do not wish to take oral contraceptives, who are lactating, or who are awaiting hospital admission for sterilisation.