Contrasting patterns in in vitro fertilization pregnancy rates among fresh autologous, fresh oocyte

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Contrasting patterns in in vitro fertilization
pregnancy rates among fresh autologous, fresh
oocyte donor, and cryopreserved cycles with the
use of day 5 or day 6 blastocysts may reflect
differences in embryo-endometrium synchrony.

• Bruce S. Shapiro, M.D., Said T. Daneshmand, M.D.,
  Forest C. Garner, M.Sc.,
• Martha Aguirre, Ph.D., and Richard Ross, M.Sc.
• Fertili Steril 20085920-6

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• Objective
• To compare the effect of day 5 and day 6
  blastocyst transfers on patterns of implantation
  rates and pregnancy rates (PRs) among fresh
  autologous, oocyte donor, and frozen ET (FET)
  cycles.
• Design
• Retrospective study.
• Patient(s)
• The study included 377 fresh autologous
  cycles, 106 autologous FET cycles, and 56 fresh
  oocyte donor cycles.
• Main Outcome Measure(s)
• Implantation rates and clinical PRs.

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RESULTS

• During the study period, there were 377 fresh
  autologous blastocyst transfer cycles, 106 FET
  cycles, and 56 donor cycles that met the basic
  inclusion criteria.
• These criteria required that embryos must have
  been transferred or frozen as day 5 or day 6
  blastocysts during the 20-month period from
  January 1, 2004 to August 31, 2005.
• The oocyte donor cycles must have used donors 35
  years of age.

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• Result(s)
• The clinical PR for day 5 blastocyst
  transfers was higher than for day 6 blastocyst
  transfers in fresh autologous cycles (PRs, 51.0
  and 33.3, respectively).
• However, there was no significant difference
  between transfers of blastocysts cryopreserved on
  day 5 and day 6 in FET cycles (PRs, 63.6 and
  58.9, respectively).
• Furthermore, day 6 blastocyst transfers
  significantly outperformed day 5 transfers in
  donor cycles (PRs, 63.0 and 86.2,
  respectively), a reversal of the pattern seen in
  the fresh autologous cycles.
• Day 6 blastocysts were associated with a
  significantly greater PR in FET cycles than in
  fresh autologous cycles (58.9 and 33.3,
  respectively).

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DISCUSSION

• Studies of shared oocyte cycles, where oocytes
  are split between oocyte producers and
  recipients, revealed that the recipients have
  higher PRs and implantation rates than the
  producers (Check JH et al.J Assist Reprod Genet
  19991641620.).

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• Substantially different success rates in fresh
  and FET cycles must reflect different
  receptivities of the endometrium, less any
  negative effects of cryopreservation on the
  embryos.
• However, cryopreserved day 6 blastocysts in FET
  cycles outperformed day 6 blastocysts in fresh
  autologous cycles.
• Furthermore, cryopreserved day 6 blastocysts
  performed on a par with cryopreserved day 5
  blastocysts in FET cycles.
• It seems implausible that cryopreservation could
  have improved the embryos.

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• The superior PR for day 6 blastocysts in donor
  cycles, compared to their day 5 counterparts,
  contrasts with the pattern seen in fresh
  autologous cycles.
• The artificial cycles have a shorter and more
  precisely controlled duration of P exposure,
  enabling optimal and reproducible synchronization
  that results in consistently better synchrony of
  day 6 blastocysts with the endometrium in these
  donor cycles.

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• The greater PR (86.2) with day 6 transfers in
  donor cycles corresponds with a greater duration
  of P supplementation, perhaps with resultant
  better synchrony.
• Embryo-grading systems that emphasize rapid
  embryo development are appropriate for fresh
  autologous IVF cycles.
• However, grading systems for donor cycles should
  favor those embryos best synchronized with the
  endometrium this, in turn, will depend on the
  timing of P initiation.

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• It was suggested that the solution to the
  asynchrony problem in fresh cycles may be the use
  of antiprogestins to block the action of P.
• Antiprogestins administered with proper timing
  might reduce or prevent such endometrial
  advancement. Initial research in this area has
  been promising (Paulson RJ et al. Fertil Steril
  1997).
• Another approach might be to control E2
  production and the resulting uterine
  hypersensitivity to P because of up-regulation of
  P receptors.

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• From the data here. However, synchrony may have
  the larger effect, owing to the reversal of the
  relative performance of day 5 and day 6
  blastocysts in donor cycles.
• The effects noted here suggest that many IVF
  cycle failures may be caused, in part, by
  suboptimal synchrony between the endometrium and
  otherwise viable embryos.

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Recommendation

• 1.Eencourage the cryopreservation of
  supernumerary embryos reaching the blastocyst
  stage beyond day 5.
• 2.The greater PR (86.2) with day 6 transfers in
  donor cycles corresponds with a greater duration
  of P supplementation, perhaps with resultant
  better synchrony. (P initiated on the day of
  oocyte retrieval, day 6 blastocysts transferred
  on day 7 of P supplementation)

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• 3.The solution to the asynchrony problem in fresh
  cycles may be the use of antiprogestins to block
  the action of P.
• 4.That many IVF cycle failures may be caused, in
  part, by suboptimal synchrony between the
  endometrium and otherwise viable embryos.

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Delayed blastocyst transfer is the window
shutting?
Thank you for your attention