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Table 4 Maternal characteristics and pregnancy complications of pregnancies carried to delivery after transferring embryos with or without blastomere loss

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 = 2962) Blastomere loss group (n = 407) p value
  No. (%) No. (%)
Maternal socio-demographic characteristics    
 Pre-gestational BMI, mean (SD), kg/m2 21.79 ± 2.92 21.63 ± 2.66 0.265
 Education attainment    
  Primary school or lower 104 (3.5) 19 (4.7) 0.487
  Middle or high school 1524 (51.5) 204 (50.1)
  Collage or above 1334 (45.0) 184 (45.2)
 Maternal smoking during pregnancy 5 (0.2) 1 (0.3) 0.538
 Paternal smoking during pregnancy 379 (12.8) 71 (17.4) 0.010
History of reproduction    
 Parity 164 (5.5) 32 (7.9)  
  1 155 (5.2) 30 (7.4) 0.109
   ≥ 2 9 (0.3) 2 (0.5)
 Number of previous abortion    
  0 1597 (53.9) 184 (45.2) 0.004
  1–2 1095 (37.0) 180 (44.2)
   ≥ 3 270 (9.1) 43 (10.6)
 Previous ectopic pregnancy    
  No 2935 (99.1) 403 (99.0) 0.784
  Yes 27 (0.9) 4 (1.0)
 Duration of infertility, year    
   ≤ 2 863 (29.1) 125 (30.7) 0.795
  3–4 1008 (34.0) 137 (33.7)
   ≥ 5 1091 (36.8) 145 (35.6)
 Primary infertility    
  No 1555 (52.5) 179 (44.0) 0.001
  Yes 1407 (47.5) 228 (56.0)
 Causes of infertility    
  Tubal infertility 1625 (54.9) 222 (54.6) 0.633
  Anovulatory 70 (2.4) 12 (3.0)
 Endometriosis 60 (2.0) 8 (2.0)
  Male-factor infertility 549 (18.5) 78 (19.2)
  Unexplained infertility 87 (2.9) 6 (1.5)
  Combineda 571 (19.3) 81 (19.9)
 Type of embryo cryopreservation    
  Slowing freezing 1037 (35.0) 318 (78.1) < 0.001
  Vitrification 1925 (65.0) 89 (21.9)
 Type of FET cycle    
  Natural 1559 (52.6) 216 (53.1) 0.435
  HRT 858 (29.0) 126 (31.0)
  OS 545 (18.4) 65 (16.0)
Pregnancy complications
 Gestational diabetes mellitus    
  No 2773 (93.6) 383 (94.1) 0.707
  Yes 189 (6.4) 24 (5.9)
 Hypertensive disorder    
  No 2525 (85.3) 349 (85.8) 0.994
  Gestational hypertension 201 (6.8) 27 (6.6)
  Mild pre-eclampsia 166 (5.6) 22 (5.4)
  Wild pre-eclampsia 70 (2.4) 9 (2.2)
 Intrahepatic cholestasis of pregnancy    
  No 2856 (96.4) 388 (95.3) 0.276
  Yes 106 (3.6) 19 (4.7)
 Amniotic fluid abnormality    
  No 2842 (96.0) 388 (95.3) 0.835
  Hydramnios 46 (1.6) 7 (1.7)
  Oligohydramnios 74 (2.5) 12 (3.0)
 Preterm delivery b    
  No 2323 (78.4) 326 (80.1) 0.741
  Preterm 546 (18.4) 69 (17.0)
  Very preterm 93 (3.1) 12 (3.0)
 Mode of delivery    
  Vaginal 456 (15.4) 41 (10.1) 0.005
  Cesarean section 2506 (84.6) 366 (89.9)
  1. FET frozen-thawed embryo transfer, BMI body mass index, HRT hormone replacement therapy, OS ovarian stimulation, NA not accessible
  2. aCombined was defined as two or more infertile causes mentioned above
  3. bPreterm was defined as delivery prior to 37 gestational weeks, and very preterm was defined as delivery between 28 and 32 gestational weeks