105 infertile women are enrolled in the randomized controlled trial: 70 women with a history of RIF with donated oocytes and 35 infertile women undergoing the first oocyte donation attempt. Women receiving donated oocytes are treated with progressively increasing doses of oral estradiol followed by intravaginal progesterone after previous pituitary desensitization with GnRH agonist. 35 RIF patients are treated with GH (GH patients) while the rest 35 RIF patients (non-GH patients) and 35 first-attempt patients (positive control group) are not.

This study includes in total 105 infertile couples treated by assisted reproduction with oocyte donation. Seventy couples that have experienced at least two previous failures with this approach at our clinic are referred to as recurrent implantation failure (RIF) patients throughout this study. Thirty five of these couples are included in the GH-treatment protocol, while the remaining 35 couples are treated in a usual way (non-GH group). Other 35 couples, treated in the same period and undergoing their first oocyte donation attempt, are included as a positive control group.

RIF patients are randomly allocated into two groups (labeled I and II). Then the assignments are concealed in sealed opaque envelopes until the time of enrollment: group I (GH patients) and group II (non-GH patients). All injections are performed by an independent nurse who is informed by the trial coordinator of each woman´s number and the treatment allocation. Consequently, both the clinician and the patients are blinded as to the treatment received. The positive control (non-RIF) group is created by allocating all consecutive couples undergoing their first oocyte donation attempt. This allocation started immediately after the allocation of the first RIF couple and will be terminated as soon as 35 cases are enrolled.

Ovarian stimulation of the oocyte donors is as follows: oocyte donors are stimulated with the use of a long GnRH agonist protocol and human recombinant FSH (Puregon or Gonal F). Human menopausal gonadotropin (Menopur) is added when blood LH concentration, which is repeatedly determined during ovarian stimulation, falls below 1 IU/l. Final oocyte maturation is triggered by subcutaneous injection of 250 micrograms recombinant hCG (Ovitrelle), when at least 5 follicles measure 18 mm or more. Ovarian puncture for oocyte recovery is performed 36.5 h after recombinant hCG injection.

Oocyte recipients are treated with progressively increasing doses of orally administered pure estradiol (Provames) or estradiol valerate (Progynova) after previous pituitary desensitization with a single injection of the long-acting preparation of GnRH agonist triptorelin (Decapeptyl 3,75 mg). The interval between triptorelin injection and the beginning of oral estradiol treatment is ranging between 8 and 20 days. This interval is determined individually, in each case, in view of the optimal synchronization of the recipient's endometrial development and the follicular growth of the corresponding donor.

Inclusion Criteria for oocyte recipients:

• age below 51 years
• 2 or more previous implantation failures in oocyte donation program
• voluntary participation

Inclusion Criteria for oocyte donors:

• age up to 25 year
• healthy
• voluntary participation

Exclusion Criteria:

• cancellation of the treatment
• no wish to participate any longer

No other IPD is foreseen than scientific publications.

The assignments are concealed in sealed opaque envelopes until the time of enrollment: group I (GH patients) and group II (non-GH patients). All injections are performed by an independent nurse who is informed by the trial coordinator of each woman´s number and the treatment allocation. Consequently, both the clinician and the patients are blinded as to the treatment received.