[FIVNAT. Influence of attempt rank in in vitro fertilization].

The French national register on in vitro fertilization (IVF) FIVNAT, which has collected most of the oocyte pick-ups realised in France since 1986 has allowed us to build a cohort of 35,714 couples, of which the first recovery took place between 1990 and 1994 and followed up to a pregnancy or to the 31st of december, 1996. The per recovery clinical pregnancy rate decreased from 20.2% on the first attempt to 17.