Abstract

PIP: Many recent advances in fertility control have involved progestin-only contraception. The progestin-only oral contraceptive, which has a failure rate of 1-2.5%, is especially suited to women who are breastfeeding or cannot tolerate estrogen. The levonorgestrel implant, Norplant, is effective for 5 years and has a 1.5% failure rate. Currently under development is Norplant-2--a system that requires 2 rather than 6 capsules, lasts for 3 years, and is as effective as Norplant-1. Also under development is a biodegradable progestin-only implant. However, there are many side effects associated with these methods. Irregular bleeding occurs in 60-70% of Norplant acceptors and leads 12-20% of these women to discontinue implant use. Headaches and acne occur in 5-20% of users of levonorgestrel methods. More significant are concerns that progestin tends to increase low density lipoprotein levels. Although initial human trials have indicated a drop of 5-15% in both these levels, studies in macaque monkeys have found that progestin-only contraception is more likely to cause atherosclerosis than an estrogen-progestin formulation.