“I am in full agreement with researchers at Cambridge University in the United Kingdom who following a recent published a report on their observation that FET enhances IVF outcome, stated that this could represent one of the most “exciting” IVF revelations of the last  25 years.” I am often asked by patients whether there is a benefit in doing frozen embryo transfers over fresh embryo transfers and how this decision impacts IVF outcome. Women undergoing IVF usually have one or more fresh embryos transferred within a week of their eggs being harvested following ovarian stimulation with fertility drugs I have long held that, provided embryos are frozen in their most advanced (blastocyst) stage of development,  that freezing is effected using ultra-rapid vitrification (rather than using previous slow-freezing methods) and optimal technique is employed during the performance of the freezing process, that Frozen Embryo Transfer (FET) will not compromise IVF outcome. It has been my expressed position that while this benefit is least apparent in younger women (<35y) and those who have normal ovarian reserve, it quite profound when comes to older women , diminished reserve (dor) with polycystic syndrome (pcos). is my opinion that this largely attributable the fact ovaries of latter group a tendency over-produce  male hormones (androgens) such as androstenedione testosterone which reach follicles in excess compromising egg development maturation thereby  increasing incidence numerical chromosomal irregularities during meiosis (maturational division) diminishing  “competency” produce viable embryos following fertilization. recent study reported from cambridge united kingdom has now confirmed observation, reporting roughly 50% improvement per embryo transferred fet compared fresh transfers. reason for ivf outcome obviously little do any direct influence freezing on competency. rather, likely due targeted measured hormonal manipulation preparation improving optimize endometrial receptivity. also serves explain why women, dor are high responders (e.g. pcos) accordingly dysfunctional production response stimulation fertility drugs ones most benefit more programmed development. regardless however, should be pointed out new revelation showing can only enhance results, comforting undergoing other established indications as: preimplantation genetic testing (pgt) and/or diagnosis (pgd), both preclude performing transfer same cycle retrieval and  recipient situations donor-ivf, gestational surrogacy (gs) adoption (ea).