During an In Vitro Fertilization (IVF) attempt, several embryos are obtained but not all of them can be transferred to the uterus in the same cycle due to the risk of multiple pregnancies. Thus, it is very common for these couples to benefit from cryopreservation. Patients scheduled for frozen embryo transfer (TEC) receive estrogen and progesterone replacement therapy to prepare the endometrium for implantation. Data from the literature recently showed that low progesterone on the day of embryo transfer was responsible for a significantly higher rate of implantation failure and miscarriage.

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)