Inclusion Criteria:  Patient in round 1 or 2 of IVF or IVF-ICSI with transfer of a fresh embryo with a normal preimplantation assessment, without antibiotic treatment in the 3 months preceding the sample. The patient must have given their free and informed consent and signed the consent form The patient must be a member or beneficiary of a health insurance plan  Exclusion Criteria:  Use of antibiotics in the 3 months preceding the sample. Patient presenting an anomaly in the implantation assessment. Presence of uterine malformation, hydrosalpinx, chronic vaginosis. Patient undergoing a protocol to study endometrial receptivity. Patient of African American, African or Latin American origin (patients born to two parents of Hispanic origin) as people of African and Hispanic origin have a type IV flora vs people of Caucasian origins who have type I, II, III and V of the Ravel classification . Cancellation of the procedure for various reasons (stimulation failure, collection failure, fertilization failure or embryonic segmentation). Patient taking a freeze-all approach (freezing of the embryos) for various causes (risk of ovarian hyperstimulation, increase in progesterone, too thin endometrium, etc.). The subject is participating in a category 1 interventional study, or is in a period of exclusion determined by a previous study The subject refuses to sign the consent It is impossible to give the subject informed information The patient is under safeguard of justice or state guardianship