Hormonal contraception without estrogens.

The long-term clinical effects of ethinyl estradiol and the impact on environmental safety of the alkylated estrogen components used in combined contraceptive pills remain the subject of debate. The development of improved methods for the use of progestogen-only contraception would represent a viable and desirable option. Several progestogen compounds are not alkylated, and these can be delivered through a variety of routes. Some of the progestogen-only methods are well established in clinical use. Estimates for both perfect and typical effectiveness are less than one pregnancy per 100 woman-years with oral, injectable, implantable and intrauterine methods. In practice, with the oral progestogen-only method, perfect and typical effectiveness range from three to five pregnancies per 100 woman-years. The main side effect with all progestogen-only methods is unpredictable vaginal bleeding during the first months of use, and this may lead to discontinuation. Nevertheless, continuation of use is more frequent if patients are well informed of this side effect before treatment begins. No cardiovascular- and cancer-related side effects have been proven.