Table 1 Basic clinical data from subjects in this study

FET cycles (n)

743

809

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Age (y)

30.75 ± 3.49

30.53 ± 3.38

0.203

Infertility duration (y)

3.65 ± 2.74

3.87 ± 2.88

0.120

Times of abortion

0.72 ± 0.91

0.71 ± 0.98

0.933

BMI (kg/m²)

20.89 ± 2.43

21.13 ± 2.50

0.056

Endometrial thickness (mm)

9.44 ± 1.77

9.47 ± 1.77

0.765

Basal FSH (IU/L)

6.95 ± 1.78

6.81 ± 1.68

0.111

Basal LH (IU/L)

5.81 ± 3.12

5.82 ± 3.67

0.967

Percentage of natural cycle

66.08 (491/743)

61.93 (501/809)

0.089

Mean number of frozen blastocysts

5.09 ± 3.30

5.18 ± 3.40

0.204

Mean number of embryos used for culture blastocyst

11.72 ± 6.09

11.99 ± 6.13

0.428

Mean number of cycles

1.19 ± 0.39

1.17 ± 0.37

0.0714

Mean number of collected oocytes

16.83 ± 7.21

17.47 ± 7.59

0.077