Implantable contraception

ABSTRACT

This article reviews the advantages and disadvantages of progestogen-only contraceptive implants in light of the development of Implanon®, a new, single-rod, etonogestrel-releasing system. Implants rapidly produce serum progestogen levels sufficient to ensure contraception for 1–5 years. The steady release of progestogen avoids the peaks and troughs associated with oral contraceptives, the profound ovarian suppression observed with depot injections and the need for user compliance. Implants have few serious complications. Ectopic pregnancy rates are low, and follicular hypertrophy is generally self-limiting. The principal acceptability limitation to both users and providers of Norplant® is insertion and removal. Implanon® is easy to insert and remove with minimal complications and pain. The main adverse event causing discontinuation of implants is a change in bleeding pattern. However, with good counselling, this is well tolerated by most women. Implants thus provide an effective, safe, economical and convenient alternative to oral, injectable or intrauterine contraceptives. Implanon® is an extremely effective single-rod implant with a Pearl index of 0. It employs a new polymer and a less androgenic progestogen. These features provide easier insertion and removal for both users and clinicians, a more stable release rate and potentially fewer adverse androgenic effects compared with existing formulations.

KEY WORDS:

• Progestogen-only implants
• Oral contraception
• Injectable progestogens
• Etonogestrel
• Levonorgestrel
• Medroxyprogesterone acetate