Table 2 Baseline characteristics according to the pregnancy outcomes in the training cohort (N = 1853)

Female age (years)

33.06 ± 3.66

32.17 ± 3.53

 < 0.001

BMI (kg/m²)

23.23 ± 3.64

23.57 ± 3.86

0.063

Duration of infertility (years)

4.22 ± 3.24

3.99 ± 2.96

0.110

AMH (ng/ml)

3.68 ± 3.08

4.17 ± 3.10

0.001

Baseline FSH (IU/L)

6.31 ± 2.29

5.99 ± 2.30

0.004

Endometrial thickness (cm)

0.96 ± 0.22

1.02 ± 0.21

 < 0.001

VI

5.00 ± 3.17

6.08 ± 3.88

 < 0.001

FI

32.20 ± 6.28

33.41 ± 4.15

 < 0.001

RI

0.52 ± 0.11

0.50 ± 0.08

 < 0.001

PI

0.76 ± 0.23

0.75 ± 0.20

0.100

FET protocols, n(%)

0.129

 Artificial cycle

73 (10.64%)

152 (13.02%)

 Natural cycle

613 (89.36%)

1015 (86.98%)

Type of infertility, n(%)

0.069

 Primary infertility

348 (50.73%)

643 (55.10%)

 Secondary infertility

338 (49.27%)

524 (44.90%)

Infertility diagnosis, n(%)

0.230

 Female factor

422 (61.52%)

682 (58.44%)

 Male factor

70 (10.20%)

156 (13.37%)

 Multiple factors

170 (24.78%)

291 (24.94%)

 Unexplained and other

24 (3.50%)

38 (3.26%)

Type of embryos transferred, n(%)

 < 0.001

 Cleavage embryo

430 (62.68%)

579 (49.61%)

 Blastocyst

256 (37.32%)

588 (50.39%)

No. of embryos transferred, n(%)

0.929

 1

190 (27.70%)

321 (27.51%)

 2

496 (72.30%)

846 (72.49%)

Endometrial pattern, n (%)

0.718

 Type A

233 (33.97%)

406 (34.79%)

 Type non-A

453 (66.03%)

761 (65.21%)

No. of Sub-endometrial blood, n (%)

 < 0.001

 A

69 (10.06%)

18 (1.54%)

 B

455 (66.33%)

621 (53.21%)

 C

162 (23.62%)

528 (45.24%)

Endometrial blood flow classification, n (%)

 < 0.001

 I

65 (9.48%)

71 (6.08%)

 II

611 (89.07%)

1049 (89.89%)

 III

10 (1.46%)

47 (4.03%)