[Evolution of prognostic criteria of in vitro fertilization according to the rank of attempts. FIVNAT].

Data from all IVF cycles of 8,362 patients that were initiated their first attempt between 1986 and 1987 were analysed until a clinical pregnancy was achieved or they withdrew from the program. The general characteristics, success rate and success factors are the same that indicated in FIVNAT analysis. The transfer rate and the number of transferred embryos increase according to the rank of attempt. By contrast, the pregnancy rate declines with successive cycles. After each cycle the percent of cancelled attempt is high (40%). This cancelled rate is not associated with infertility diagnoses. It increases with women's age and especially with the failure of fecundation. All the same, the cancelled rate is frequent among all patients and asks us about risk factors and prevention.