Abstract

Clinical outcomes following frozen-thawed cleavage embryo transfer versus frozen-thawed blastocyst transfer in high responder patients undergoing in vitro fertilisation/intracytoplasmic sperm injection cycles are still debated. In a retrospective study, 106 high responder patients who were candidate for 'freeze-all embryos' were recruited. Frozen-thawed embryos were transferred at the cleavage stage (n = 53) or the blastocyst stage (n = 53). Clinical pregnancy was considered as the primary outcome and chemical pregnancy, ongoing pregnancy, implantation rate, and fertilization rate, as well as miscarriage rate, were measured as the secondary outcome. Clinical (47.2% vs. 24.5%), chemical (56.6% vs. 32.1%), and ongoing pregnancy rates (37.7% vs. 17%) as well as implantation rates (33.6% vs. 13.5%) were significantly higher in the blastocyst group compared with the cleavage group respectively (P < 0.05). Miscarriage rate was comparable between groups (P > 0.05). Transfer of frozen-thawed embryos at the blastocyst stage was preferable in the high responder patients to increase implantation, pregnancy and live birth rates compared with cleavage stage embryo transfer.