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Table 1 Baseline characteristics of all transfer cycles

From: Outcomes of neonates born following transfers of frozen-thawed cleavage-stage embryos with blastomere loss: a prospective, multicenter, cohort study

  Intact embryo group (n = 9846) Blastomere loss group (n = 2259) p value
No. (%) No. (%)
History of reproduction
 Age of oocyte retrieval, mean (SD), years 31.12 (4.57) 31.18 (4.05) 0.515
 Age of embryo transfer, mean (SD), years 31.64 (4.59) 31.84 (4.13) 0.046
 BMI, mean (SD), kg/m2 21.76 (3.00) 21.68 (4.35) 0.409
 Duration of infertility, mean (SD), years 4.31 (2.91) 4.42 (3.00) 0.114
 Pluriparous 731 (7.4) 176 (7.8) 0.550
 Primary infertility 5048 (51.3) 1265 (56.0) < 0.001
Causes of infertility
  Tubal infertility 5265 (53.5) 1234 (54.6) 0.188
  Anovulatory 205 (2.1) 56 (2.5)
  Endometriosis 201 (2.0) 57 (2.5)
  Male-factor infertility 1721 (17.5) 365 (16.2)
  Unexplained infertility 330 (3.4) 63 (2.8)
  Combined a 2124 (21.6) 484 (21.4)
Characteristics of FET cycle
 Type of embryo cryopreservation    
  Slowing freezing 3986 (40.5) 1793 (79.4) < 0.001
  Vitrification 5860 (59.5) 466 (20.6)
 Type of FET cycle
  Natural 5085 (51.7) 1255 (55.6) 0.004
  HRT 3063 (31.1) 654 (28.6)
  OS 1698 (17.3) 359 (15.9)
 Numbers of embryo transferred
  1 803 (8.2) 320 (14.2) < 0.001
  2 6679 (67.8) 1015 (44.9)
  3 2364 (24.0) 924 (40.9)
  1. BMI body mass index, FET frozen-thawed embryo transfer, HRT hormone replacement therapy, OS ovarian stimulation
  2. aCombined was defined as two or more infertile causes mentioned above