A regression model for the rate of success of in vitro fertilization.

The treatment of infertility by in vitro fertilization involves several aspects of human reproductive physiology. Since failures are still numerous and since improved techniques are becoming increasingly available, it is important to develop a model where the components of success are identified, allowing estimation of the occurrence of these components of success in the infertile population. The model of Speirs reduces these components to two: uterine receptivity and embryo viability. The probabilities of uterine receptivity and embryo viability were estimated here in a retrospective study of patients in a Belgian hospital sample. For comparison, Australian and U.S. data were used. It was shown that the estimate of uterine receptivity for the Belgian sample is located between the estimates for Australian and U.S. samples. In view of the psychological problem of repeated unsuccessful attempts at in vitro fertilization in some patients, it is important to be able to single out some prognostic factors that would allow more precise estimation of the probability for success in each case. A regression method was developed for that purpose. Only the effect of age, in the Belgian sample, was found to influence uterine receptivity significantly.