The aim of this study is to be able to perform on the animal (Macacus cynomolgus) a specific in utero surgical procedure for correcting congenital diaphragmatic hernia, in order to do the same on human fetuses. The surgical technique consist in operating in utero, and to put a silastic patch on the diaphragm. A good tocolysis is very necessary to prevent early abortion. Finally the fetuses' surviving is the main problem.