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Table 4 Efficiency of cryopreservation and pregnancy potential of surviving embryos

From: Should a single blastocyst transfer policy be a clinical decision or should it depend on the embryological evaluation on day 3?

  eSET with elective day 5 transfer eSET with transfer day 3 or 5 Statistical significance
No. of embryos cryopreserved 640 517  
No. of thawing cycles 188 143  
No. of embryos thawed 286 229  
No. of embryos surviving 200 150  
Transferrable survival rate 200/286 (69.9) 150/229 (65.5) NS
Subjects with thawed transfers 109 71  
Total number of thawed transfers 171 125  
Total number of clinical pregnancies 26 21  
Transfer specific pregnancy rate1 26/171 (15.2) 21/125 (16.8) NS
Subject specific pregnancy rate2 26/109 (23.9) 21/71 (29.6) NS
   Day 3 Day 5  
No. of embryos cryopreserved   154 363  
No. of thawing cycles   41 102  
No. of embryos thawed   84 145  
No. of embryos surviving   39 111  
Transferrable survival rate   39/84 (46.4) 111/145 (76.5) <0.001
Subjects with thawed transfers   26 45  
Total number of thawed transfers   28 97  
Total number of clinical pregnancies   4 17  
Transfer specific pregnancy rate1   4/28 (14.3) 17/97 (17.5) NS
Subject specific pregnancy rate2   4/26 (15.4) 17/45 (37.8) 0.05
  1. 1 Total number of pregnancies/total number of thawed transfers
  2. 2 Total number of pregnancies/number of subjects with thawed transfers