Fresh embryo transfer group N=1822
Frozen-thawed embryo transfer group N=2098
Frozen-thawed embryo transfer group N=2098
Frozen-thawed embryo transfer group N=2098
χ2/U value
P value
χ2/U value*
P value*
NC-FET group N=1353 HRT-FET group N=745
Total
Age(year) 34(32,37) 35(32,37) 34(32,37) 35(32,37) 4.14 0.126 -0.36 0.717
Prepregnancy BMI(kg/m2) 22.31(20.42,24.98) 22.29(20.31,25.15) 23.21(20.96,25.87) 22.62(20.55,25.40) 25.70 <0.001 -2.10 0.036
the number of pregnancies 213.42 <0.001 213.08 <0.001
1 1166(64.0%)①② 607(44.9%) 344(46.2%) 951(45.33%)
2 486(26.7%) 392(29.0%) 209(28.1%) 601(28.65%)
≥3 170(9.3%) 354(26.2%) 192(25.8%) 546(26.02%)
Parity 50.67 <0.001 49.92 <0.001
1 1723(94.6%)①② 1187(87.7%) 662(88.9%) 1849(88.13%)
≥2 99(5.4%) 166(12.3%) 83(11.1%) 249(11.87%)
PCOS 86(4.7%) 60(4.4%) 170(22.8%) 230(10.96%) 270.37 <0.001 51.28 <0.001
History of intrauterine operation 735(40.3%)①② 664(49.1%) 384(51.5%) 1048(49.95%) 37.51 <0.001 36.33 <0.001
Endometrial thickness(mm) 11(10,12)①② 10(9,11) 10(9,11) 10(9,11) 291.95 <0.001 -16.15 <0.001
D3 No. of embryos transferred
1735(95.22%)①②
538(39.76%)
299(40.13%)
837(39.90%)
1323.148
<0.001
1323.118
0.001
D5 No. of blastocysts transferred 87(4.77%) 815(60.24%) 446(59.87%) 1261(60.10%) Ref Ref Ref Ref
Rate of ICSI 656(36.00%)①② 566(41.83%) 313(42.01%) 879(41.90%) 14.22 0.001 14.21 <0.001