In vitro fertilization (IVF) is a treatment in which embryos are generated in the laboratory from the gametes of the future parents or from anonymous donors. These embryos are then placed in the woman's uterus by embryo transfer.
In order for these embryos to implant in the endometrium, the endometrium must have the same characteristics as it would have had if fertilization had taken place in the uterus and not in the laboratory.
This implies that the endometrium must be exposed to the same hormonal variations as in a natural cycle. For this purpose, progesterone administered exogenously by means of vaginal or oral ovules is used.