[Biological and clinical aspects of in vitro fertilization]

Roughly 15% of the French population is concerned by a problem of unfertility. Assisted reproductive technique may be proposed as a way to answer to this problem. In an IVF laboratory, several procedures may be carried out to obtain embryos in vitro, including micromanipulation as intracytoplasmic sperm injection. Among a high number of embryos obtained, only few will be selected for embryo transfer. The aim of this activity is to define which embryo present the best characteristics to undergone a positive implantation. Several criteria have been identified and positively correlated with pregnancy rates, however these criteria are not absolute. Finally, the medical team is often pressed to propose a double or a triple embryos transfer, in order to maintain an acceptable pregnancy rate but exhibiting the couple to a risk of multiple pregnancy.