Blastocyst-stage versus cleavage-stage embryo transfer in women with high oestradiol concentrations: randomized controlled trial.

This prospective, randomized, controlled trial tested the hypothesis that delaying embryo transfer to the blastocyst stage can increase the probability of clinical pregnancy and live birth in women with high oestradiol concentrations on the day of human chorionic gonadotrophin (HCG) undergoing intracytoplasmic sperm injection using the long protocol. A total of 200 women with oestradiol >3000 pg/ml on the HCG day with four or more good-quality, day-3 embryos were randomized in a 1:1 ratio to undergo day-3 or day-5 embryo transfer. Clinical pregnancy rates (CPR; 41% versus 59%; relative risk 0.70, 95% CI 0.52–0.93) and ongoing pregnancy/live-birth rates (35% versus 52%; relative risk 0.67, 95% CI 0.46–0.93) were lower in women undergoing cleavage-stage than blastocyst-stage embryo transfer. Using receiver operating characteristic curves, among women undergoing cleavage-stage embryo transfer, a detrimental cut-off value for not achieving pregnancy for oestradiol was 4200 pg/ml, with lower CPR and ongoing pregnancy/live-birth rates (P = 0.006 and 0.02, respectively). No detrimental cut-off value for oestradiol was identified among women undergoing blastocyst-stage embryo transfer. Delaying embryo transfer to the blastocyst stage can increase the probability of pregnancy in women with high oestradiol on the HCG day