| Age – years (mean ± SD) | 33.0 ± 4.7** | 31.4 ± 4.0** | 33.5 ± 4.9** | 31.8 ± 4.5** |
| Age group – years (%) |
| ≤25 | 71 (4.5) | 71 (7.0) | 33 (3.8) | 40 (7.4) |
| 26–30 | 433 (27.4) | 362 (35.5) | 214 (24.5) | 166 (30.6) |
| 31–35 | 619 (39.2) | 416 (40.8) | 326 (37.3) | 224 (41.3) |
| 36–40 | 368 (23.3) | 163 (16.0) | 230 (26.3) | 97 (17.9) |
| >40 | 89 (5.6) | 8 (0.8) | 70 (8.0) | 16 (2.9) |
| BMI – kg/m2 (mean ± SD) | 20.9 ± 2.3 | 21.0 ± 2.3 | 21.0 ± 2.4 | 21.0 ± 2.3 |
| Anti-Müllerian hormone – ng/mL (mean ± SD) | 5.4 ± 3.6** | 6.3 ± 3.9** | 4.1 ± 2.9** | 5.4 ± 3.6** |
| Antral follicle count – n (mean ± SD) | 13.0 ± 6.8** | 14.9 ± 6.7** | 11.2 ± 6.4** | 12.7 ± 6.4** |
| Duration of infertility – year (mean ± SD) | 5.0 ± 3.5* | 4.6 ± 3.3* | 5.0 ± 3.5 | 4.8 ± 3.2 |
| Type of infertility – n (%) | * | * | | |
| Primary | 620 (39.2) | 453 (44.4) | 512 (58.6) | 336 (61.9) |
| Secondary | 960 (60.8) | 567 (55.6) | 361 (41.4) | 207 (38.1) |
| IVF indications – n (%) | ** | ** | ** | ** |
| Male factor infertility | 546 (34.6) | 434 (42.5) | 266 (30.5) | 214 (39.4) |
| Tubal | 321 (20.3) | 198 (19.4) | 168 (19.2) | 103 (19.0) |
| Diminished ovarian reserve | 218 (13.8) | 64 (6.3) | 184 (21.1) | 69 (12.7) |
| Unexplained | 219 (13.9) | 133 (13.0) | 129 (14.8) | 64 (11.8) |
| Ovulation disorder | 129 (8.2) | 116 (11.4) | 54 (6.2) | 57 (10.5) |
| Endometriosis | 47 (3.0) | 19 (1.9) | 22 (2.5) | 9 (1.7) |
| Others | 100 (6.3) | 56 (5.5) | 50 (5.7) | 27 (5.0) |
| Number of IVF attempts – n (%) | * | * | * | * |
| 1 | 1181 (74.7) | 823 (80.7) | 680 (77.9) | 422 (77.7) |
| 2 | 262 (16.6) | 146 (14.3) | 123 (14.1) | 86 (15.8) |
| 3 | 89 (5.6) | 38 (3.7) | 46 (5.3) | 19 (3.5) |
| 4 | 25 (1.6) | 7 (0.7) | 17 (1.9) | 6 (1.1) |
| 5 | 15 (0.9) | 3 (0.3) | 6 (0.7) | 5 (0.9) |
| ≤6 | 8 (0.5) | 3 (0.3) | 1 (0.1) | 5 (0.9) |
| Duration of stimulation – days (mean ± SD) | 9.2 ± 1.5 | 9.1 ± 1.4 | 9.1 ± 1.4 | 9.0 ± 1.3 |
| Total dose of rFSH used – IU (mean ± SD) | 2648.3 ± 909.9** | 2424.4 ± 843.5** | 2997.5 ± 837.0** | 2725.6 ± 781.8** |
| Type of trigger – n (%) | | | * | * |
| Agonist trigger | 174 (11.0) | 98 (9.6) | 93 (10.7) | 87 (16.0) |
| hCG trigger | 1406 (89.0) | 922 (90.4) | 780 (89.3) | 456 (84.0) |
| Estradiol level on day of trigger – pg/mL (mean ± SD) | 7170.6 ± 6135.3 | 7440.3 ± 6351.8 | 5235.9 ± 4773.2** | 6453.2 ± 5716.6** |
| Progesterone level on day of trigger – ng/mL (mean ± SD) | 1.3 ± 1.0 | 1.3 ± 1.1 | 1.2 ± 1.1 | 1.2 ± 0.8 |
| <1.5 | 1046 (70.8) | 719 (75.4) | 665 (80.2) | 411 (80.9) |
| ≥1.5 | 431 (29.2) | 234 (24.6) | 164 (19.8) | 97 (19.1) |
| Number of oocyte retrieved – n (mean ± SD) | 12.4 ± 6.1** | 14.2 ± 6.1** | 11.2 ± 5.7** | 13.5 ± 6.4** |
| Proportion of women with the number of oocytes retrieved – n (%) |
| 1 – 3 | 28 (1.8) | 5(0.5) | 18(2.1) | 6(1.1) |
| 4 – 9 | 485 (30.7) | 217 (21.3) | 349 (40.0) | 151 (27.8) |
| 10 – 15 | 651 (41.2) | 460 (45.1) | 305 (34.9) | 206 (37.9) |
| >15 | 416 (26.3) | 416 (26.3) | 201 (23.0) | 180 (33.1) |
| Number of embryos – n (mean ± SD) | 5.6 ± 3.3** | 7.0 ± 3.3** | 5.5 ± 3.4** | 7.0 ± 3.6** |
| Number of good embryos – n (mean ± SD) | * | * | | |
| Fresh ET | 1073 (67.9) | 741 (72.6) | 585 (67.0) | 347 (63.9) |
| Frozen ET | 507 (32.1) | 279 (27.4) | 288 (33.0) | 196 (36.1) |
| Number of subsequent FET after first transfer – n(%) | ** | ** | ** | ** |
| 0 | 923 (58.4) | 477 (46.8) | 364 (41.7) | 159 (29.3) |
| 1 – 2 | 489 (30.9) | 357 (35.0) | 388 (44.4) | 288 (53.0) |
| 3 – 4 | 137 (8.7) | 146 (14.3) | 117 (13.4) | 83 (15.3) |
| ≥5 | 31 (2.0) | 40 (3.9) | 4 (0.5) | 13 (2.4) |