Injectable contraceptives

Injectable hormonal contraceptives (1) are slow release, long lasting progesterone preparations administered intramuscularly at intervals from 1 to 6 months. Common preparations include medroxyprogesterone acetate and norethisterone enanthate.

The main disadvantages are due to the progesterone. Many experience some degree of menstrual disturbance; in some, this can be irregular uterine bleeding which may be heavy and prolonged whilst others may experience amenorrhoea.

Injectable contraception however, may be particularly suited:

• following rubella vaccination in the puerperium
• while awaiting for vasectomy to be proven in a partner
• in women with a chaotic lifestyle where taking an oral contraceptive regularly is difficult

Injectable hormonal contraception is 96% to 99% effective for pregnancy prevention (typical to perfect use) (2)

References:

1. Progestogen-only Injectable Contraception Clinical Guidance. Faculty of Sexual and Reproductive Healthcare (December 2014, amended 2020)
2. Hatcher R. Contraceptive technology. 21st ed. New York: Ardent Media; 2018.