This is the first study to investigate, whether pregnancy and implantation rates would improve in patients with recurrent implantation failure (RIF), if all embryos were to be frozen and transferred in a consecutive natural cycle.

There is growing evidence that elective frozen-thawed embryo transfer in a non-stimulated cycle (freeze-all policy) would eliminate the risk of controlled ovarian stimulation and resulting in better endometrial receptivity and lower uterine contractility as compared with fresh intracytoplasmic sperm injection (ICSI) cycles.

RIF refers to women who fail to achieve a clinical pregnancy, in a minimum of three embryo transfer cycles with at least four good-quality embryos were transferred in a woman < 40 years. It affects approximately 10% of ICSI cases. Many management protocols aimed to enhance ICSI outcome in cases of RIF, however, none of them examined the effect of freeze all policy in this category of patients.

Inclusion Criteria:

1. gonadotropin-releasing hormone agonist and recombinant follicle-stimulating hormone (FSH) in a long protocol cycles;
2. female partners were under age of 40 years;
3. all the patients had a history of recurrent implantation failure i.e: failed to achieve a clinical pregnancy after at least three fresh ICSI cycles where at least 8 good embryos were transferred;
4. their embryos were pushed to Day 5 resulting in blastocysts, and undergo embryo transfer day 5 or vitrification on day 5;
5. endometrial thickness ≥ 7 mm;
6. selected embryos for embryo transfer were blastocysts. -

Exclusion Criteria:

Couples with testicular or epididymal sperm were excluded.

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