Early compaction at day 3 may be a useful additional criterion for embryo transfer
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The reduction of the number of embryos transferred while maintaining a satisfactory rate of pregnancy (PR) with in vitro fertilization calls for a refined technique of embryonic selection. This prospective study investigates the significance of early embryonic compaction at day 3 as a marker of the chances of implantation.
We examined 317 transfers and their outcome involving 509 embryos including 91 compacted embryos.
Early compaction seems linked with the ovarian response to stimulation and embryonic quality. The PR is significantly increased when the embryonic cohort contains at least one compacted embryo (44 % versus 29.5 %, p = 0.01), and when at least one compacted embryo is transferred (44 % versus 31 %, p < 0.05). The analysis of our single embryo transfers shows that the implantation rates are significantly better for compacted embryos (50 % versus 30 %, p < 0.05) (OR 2.98; CI 1.02–5.28).
Thus, early compaction, sometimes observed at day 3, may serve as a useful additional criterion for selecting the embryos transferred.
KeywordsEarly compaction Cleavage stage Embryonic selection Transfer at day 3
We thank Ms. C. Douillard, M. Guezenec, S. Lehais and C. Moyon, technicians at the In Vitro Fertilization Laboratory of the University Hospital of Angers, for their participation in the classification of embryos. We thank P. Saulnier for his help in the statistical analysis. We are grateful to Kanaya Malkani for his critical reading and comments on the manuscript.