Table 1 Demographics and baseline characteristics of the participants in the first oocyte retrieval cycle

Patients (n)

4470

2270

1110

1095

8753

Age of female

30.21 ± 2.76^a

38.01 ± 2.83^b

30.32 ± 2.71^a,d

39.37 ± 3.38^c

30.44 ± 3.85^d

<0.05

Percentage of age

a

b

c

d

e

<0.05

  ≤ 30

2234 (50.0%)

0 (0.0%)

541 (48.7%)

0 (0.0%)

4760 (54.4%)

  > 30, ≤35

2236 (50.0%)

494 (21.8%)

569 (51.3%)

141 (12.9%)

3103 (35.5%)

  > 35, ≤40

0 (0.0%)

1360 (59.9%)

0 (0.0%)

564 (51.5%)

796 (9.1%)

  > 40

0 (0.0%)

416 (18.3%)

0 (0.0%)

390 (35.6%)

94 (1.1%)

AFC

11.17 ± 5.77^a

8.99 ± 4.09^b

2.19 ± 1.65^c

2.51 ± 1.32^c

15.24 ± 6.21^d

<0.05

Percentage of AFC

a

b

c

c

d

<0.05

  < 4

0 (0.0%)

0 (0.0%)

750 (67.6%)

776 (70.9%)

0 (0.0%)

  ≥ 4, < 10

2185 (48.9%)

1502 (66.2%)

360 (32.4%)

319 (29.1%)

1444 (16.5%)

  ≥ 10

2285 (51.1%)

768 (33.8%)

0 (0.0%)

0 (0.0%)

7309 (83.5%)

Oocytes retrieved in the first cycle (n)

5.97 ± 2.31^a

5.27 ± 2.34^b

7.07 ± 6.67^c

3.29 ± 3.05^d

16.84 ± 6.57^e

<0.05

Type of infertility

a

b

c

d

e

<0.05

 Primary

2673 (59.8%)

848 (37.4%)

713 (64.2%)

383 (35.0%)

5059 (57.8%)

 Secondary

1797 (40.2%)

1422 (62.6%)

397 (35.8%)

712 (65.0%)

3694 (42.2%)

Main etiology

a

b

c

d

e

<0.05

 Female

460 (10.3%)

240 (10.6%)

94 (8.5%)

69 (6.3%)

1076 (12.3%)

 Male

2945 (65.9%)

1401 (61.7%)

770 (69.4%)

741 (67.7%)

5567 (63.6%)

 Combined

539 (12.0%)

236 (10.4%)

126 (11.3%)

132 (12.0%)

1059 (12.1%)

 Others

526 (11.8%)

393 (17.3%)

120 (10.8%)

153 (14.0%)

1051 (12.0%)

Duration of infertility (years)

2.93 ± 2.42^a

4.08 ± 3.96^b

3.14 ± 2.46^c

4.32 ± 4.56^d

3.01 ± 2.70^a,c

<0.05

Female BMI (kg/m²)

22.00 ± 4.74^a

22.26 ± 3.07^b

21.78 ± 5.87^a,c

22.16 ± 2.88^a,b

21.64 ± 3.31^c

<0.05

Year of treatment

a

b

c

d

e

<0.05

 2013–2014

1160 (26.0%)

526 (23.2%)

309 (27.8%)

304 (27.8%)

2248 (25.7%)

 2015

859 (19.2%)

375 (16.5%)

258 (23.2%)

180 (16.4%)

1821 (20.8%)

 2016

1349 (30.2%)

730 (32.2%)

362 (32.6%)

348 (31.8%)

2188 (25.0%)

 2017

683 (15.3%)

353 (15.6%)

111 (10.0%)

172 (15.7%)

1353 (15.5%)

 2018

419 (9.4%)

286 (12.6%)

70 (6.3%)

91 (8.3%)

1143 (13.1%)

Gravidity

0.71 ± 1.27^a

1.42 ± 1.53^b

0.62 ± 1.04^c

1.48 ± 1.52^b

0.74 ± 1.09^a

<0.05

Parity

0.06 ± 0.26^a

0.27 ± 0.48^b

0.05 ± 0.23^a

0.30 ± 0.51^b

0.08 ± 0.30^c

<0.05