[Family planning in Mexico at the present time. IV. Recent advances and evaluation of contraceptive methods]. / La planificación familiar en México en el monmento actual. IV. Avances recientes y evaluación de los metodos anticonceptivos.

PIP: It has been demonstrated that preparations containing estrogens cause metabolic alterations, while such alterations do not occur or are minimal when progestogens alone are administered. Clinical studies were begun using a new polymer that makes possible the release of a constant predetermined amount of progesterone into the uterus for up to one year. The method of intrauterine release of progesterone proved to be very effective in preliminary studies: one case of pregnancy occurred among 263 women observed over 2068 months (.5 effectiveness index). The effectiveness of the method, with the release of a daily dose of 50 mcg, appears to be higher than that of other intrauterine devices and similar to that of combinations of estrogen and progestogens, that are regarded as the most effective method. A great advantage of the new method is that it does not cause systemic effects.^ieng