 If the donor meets the inclusion criteria, she will be informed of the study and, if she agrees, she will sign the informed consent. Randomization shall be performed in 2 arms; arm 1 will be administered subcutaneous progesterone 25 mgday Prolutex; Angelini, Spain, and arm 2, intramuscular progesterone 50 mgday Prontogest IBSA, Italy. In each arm 12 donors ITT population will be included. 