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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, METHODS, METHODS, METHODS, RESULTS. Meshes: Adult, Blastocyst, Cell Survival, Cryopreservation, Embryo Implantation, Embryo Transfer, Embryonic Development, Estradiol, Female, Fertilization in Vitro, Humans, Infertility, Female, Infertility, Male, Live Birth, Male, Pregnancy, Pregnancy Outcome, Pregnancy Rate, Progesterone, Progestins, Time Factors.
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Does delayed blastocyst development influence the outcome of frozen-thawed transfer cycles? Context: To compare the outcome of transfer of thawed blastocysts frozen on either day 5 or day 6 after in vitro fertilisation. Cohort observational study. Tertiary assisted conception unit in London, UK. Six hundred and forty-two consecutive nondonor programmed thawed blastocyst transfer (TBT) cycles. High-grade blastocysts were frozen on day 5 (n = 314) or day 6 (n = 328) after fertilisation using a slow-freezing protocol. Endometrial preparation was performed using estradiol valerate. Progesterone supplementation was commenced when the endometrial thickness had reached 7 mm or more. Frozen blastocysts were thawed on day 6 of progesterone supplementation and assessed immediately after thawing for survival, and after 3-4 hours for blastocoele re-expansion. Main outcome measures Thawed blastocyst survival and re-expansion rates, and pregnancy and live birth rates, per TBT. Thawed blastocyst survival and re-expansion rates were comparable between the day 5 and day 6 groups (87% versus 87%, P = 0.50 and 73% versus 71%, P = 0.35, respectively). The live birth rate was similar between the two groups (29% versus 28.5%, P = 0.93, respectively). After adjusting for confounding variables, the odds ratio (OR) of a live birth in cycles in which the thawed blastocysts were frozen on day 6 compared with day 5 was 1.23 [95% confidence interval (CI), 0.81-1.86, P = 0.34].
assistant
The pregnancy potential of high-grade blastocysts frozen on day 5 and day 6 after in vitro fertilisation and replaced in programmed TBT cycles is comparable. Final Decision: no