Table 1.
Baseline characteristics of all FET cycles.
| Characteristic | <30 y (N = 1,248) | 30–34 (N = 1,831) | 35–37 (N = 819) | 38–40 (N = 522) | 41–43 (N = 308) | 44–50 (N = 230) |
|---|---|---|---|---|---|---|
| Age of embryo transfer, mean (SD), years | 27.32 ± 1.42 | 32.11 ± 1.42 | 35.95 ± 0.93 | 38.99 ± 0.86 | 41.93 ± 0.88 | 46.89 ± 1.96 |
| Duration of infertility (years) | 2.21 ± 1.75 | 3.19 ± 1.89 | 3.69 ± 2.37 | 4.39 ± 2.88 | 5.36 ± 3.83 | 6.11 ± 4.76 |
| BMI of women | 23.09 ± 4.36 | 22.87 ± 4.67 | 23.18 ± 4.53 | 23.36 ± 4.64 | 23.63 ± 4.33 | 23.53 ± 4.73 |
| Antral follicle count (n) | 12.53 ± 8.19 | 10.68 ± 7.79 | 8.89 ± 7.49 | 7.49 ± 7.43 | 6.06 ± 6.22 | 4.39 ± 4.67 |
| Infertility causes, n | ||||||
| Tubal infertility | 489 (39.19%) | 740 (40.41%) | 367 (44.75%) | 243 (46.53%) | 144 (46.89%) | 106 (45.87%) |
| Anovulatory | 117 (9.38%) | 196 (10.69%) | 21 (2.62%) | 12 (2.39%) | 6 (1.86%) | 4 (1.83%) |
| Endometriosis | 102 (8.14%) | 172 (9.39%) | 44 (5.43%) | 28 (5.39%) | 17 (5.49%) | 10 (4.21%) |
| Male cause | 195 (15.66%) | 170 (9.28%) | 85 (10.39%) | 46 (8.82%) | 26 (8.49%) | 17 (7.18%) |
| Unexplained infertility | 30 (2.44%) | 43 (2.36%) | 21 (2.52%) | 10 (1.92%) | 15 (4.93%) | 14 (6.09%) |
| Combined | 315 (25.19%) | 510 (27.87%) | 281 (34.29%) | 183 (34.95%) | 100 (32.34%) | 79 (34.82%) |
| Previous IVF failures, n | ||||||
| 0 | 1,093 (87.55%) | 1,661 (90.72%) | 700 (85.47%) | 455 (87.16%) | 256 (83.12%) | 190 (82.61%) |
| 1–2 | 134 (10.74%) | 105 (5.73%) | 75 (9.16%) | 41 (7.85%) | 32 (10.39%) | 23 (10.00%) |
| ≥3 | 21 (1.71%) | 65 (3.55%) | 44 (5.37%) | 26 (4.99%) | 20 (6.49%) | 17 (7.39%) |
| Type of infertility | ||||||
| Primary | 843 (67.57%) | 1,086 (59.31%) | 458 (55.87%) | 246 (47.18%) | 120 (39.01%) | 57 (24.81%) |
| Secondary | 405 (32.43%) | 745 (40.69%) | 361 (44.13%) | 276 (52.82%) | 188 (60.99%) | 173 (75.19%) |
| Type of FET cycle | ||||||
| Natural | 241 (19.32%) | 379 (20.72%) | 217 (26.53%) | 147 (28.12%) | 91 (29.39%) | 68 (29.53%) |
| HRT | 320 (25.63%) | 522 (28.53%) | 260 (31.79%) | 173 (33.23%) | 117 (37.83%) | 104 (45.21%) |
| Ovarian stimulation | 687 (55.05%) | 930 (50.75%) | 342 (41.68%) | 202 (38.65%) | 100 (32.78%) | 58 (25.26%) |
| Endometrial thickness | ||||||
| Fertilization method | ||||||
| IVF | 730 (58.53%) | 1,142 (62.39%) | 532 (64.98%) | 347 (66.42%) | 204 (66.29%) | 70 (30.56%) |
| ICSI | 371 (29.69%) | 472 (25.76%) | 190 (23.23%) | 128 (24.53%) | 86 (27.93%) | 154 (66.92%) |
| Half IVF + half ICSI | 147 (11.78%) | 217 (11.85%) | 97 (11.79%) | 47 (9.05%) | 18 (5.78%) | 6 (2.52%) |