Table 1 The basic characteristics of patients with EPL and live birth among 2709 IVF cycles at the Center for Reproductive Medicine in Changchun, China, 2016–2021

Number of patients, n (%)

2298 (84.8)

411 (15.2)

–

Female age, M(Q₂₅, Q₇₅)

31 (29, 34)

32 (29, 35)

< 0.001

Male age, M(Q₂₅, Q₇₅)

32 (30, 35)

33 (30, 37)

< 0.001

Female ethnicity

 Han

2066 (89.9)

374 (91.0)

0.50

 Minority

232 (10.1)

37 (9.0)

Male ethnicity

 Han

2097 (91.3)

366 (89.1)

0.16

 Minority

201 (8.7)

45 (10.9)

Female education level, n (%)

 Primary education

96 (4.2)

16 (3.9)

0.71

 Secondary education

774 (33.7)

147 (35.8)

 Higher education

1428 (62.1)

248 (60.3)

Male education level, n (%)

 Primary

45 (12.0)

9 (2.2)

0.52

 Secondary

620 (27.0)

100 (24.3)

 Higher

1633 (71.1)

302 (73.5)

Female BMI, M(Q₂₅, Q₇₅)

22.30 (20.08, 25.00)

22.80 (20.69, 25.81)

0.009

Baseline hormone levels, M(Q₂₅, Q₇₅)

 FSH (mIU/ml)

6.18 (5.23, 7.28)

6.08 (5.08, 7.35)

0.67

 LH (mIU/ml)

4.90 (3.56, 6.73)

5.19 (3.71, 7.35)

0.034

 E₂ (pg/ml)

39.40 (29.42, 52.60)

40.30 (28.30,55.78)

0.49

Infertility type, n (%)

 Primary

1537 (6692)

258 (62.8)

0.11

 Secondary

761 (33.1)

153 (37.2)

Infertility duration, M(Q₂₅, Q₇₅)

3 (2, 5)

4 (2, 6)

0.08

Infertility diagnosis, n (%)

 Male factor

1246 (54.2)

222 (54.0)

0.60

 Female factor

669 (29.1)

113 (27.5)

 Male and female factor

364 (15.8)

74 (18.0)

 Unexplained factor

19 (0.8)

2 (0.5)

Cycle type, n (%)

 Fresh

416 (18.1)

47 (11.4)

0.001

 Frozen-thaw

1882 (81.9)

364 (88.6)