Inclusion Criteria:  Adult patient undergoing a frozen embryo transfer in an artificial cycle at the AMP center of the Toulouse University Hospital. Affiliation to a social security scheme or equivalent Patient fulfilling the conditions for access to the AMP according to French bioethics law Patient having given her consent (oral or written) after clear and fair information  Exclusion Criteria:  Patient who received intramuscular administration of progesterone during the endometrial preparation phase. Patient with comprehension difficulties. Protected adult patient (safeguard of justice, guardianship or curatorship)