[Emergency contraception].

Abstract

A specific formulation has been approved for use in Italy for emergency contraception (EC) in 2000. As expected, marketing of this levonorgestrel (LNG) only formulation has been accompanied by an increased interest and, often, controversies leading to even strong opposition on the part of those ethically opposed to the use of any method that may act after fertilization. At present, several trials on the exact mechanism of action and safety have been conducted, giving good reason for simplifying access, providing it free or over the counter, in several European countries. EC, also known as ''the morning after pill'' or postcoital contraception, is a modality of preventing the establishment of an unwanted pregnancy after unprotected intercourse and thus, probably, of reducing the number of voluntary pregnancy terminations. Two different forms are available: the hormonal and the intrauterine. Hormonal estrogen only EC was first proposed in the 60s and in 1974 Yuzpe following his studies proposed for the first time his combined regimen, that showed better efficacy and lower side effects. More recently, a new regimen, consisting of LNG, administered alone at the dose of 1.5 mg, was introduced and found in clinical trials to be more effective than the Yuzpe regimen, if taken as early as possible, within 72 h, thereby replacing the latter in common use. Mechanism of action of both hormonal preparations used for EC is inhibiting or delaying ovulation, therefore a prefertilization action. No effect has been reported on the process of implantation nor on an ongoing pregnancy. The WHO have developed a third regimen based on the use of the selective progesterone receptor modulator (antiprogestin) Mifepristone and conducted trials with different dosages, reporting similar efficacy and safety compared to LNG. Intrauterine EC was first proposed by Lippes in 1976. It has the advantage of being effective if inserted within 5 days after unprotected intercourse and the disadvantage of a greater complexity. In addition, this modality is truly interceptive, acting by preventing implantation. Pregnancy rates reported following EC using a device >300 mm2 of copper are consistently low (0.1-0.2%).