Table 1.
Baseline characteristics of the two cohorts in fresh ET and FET cycles
| Fresh cycles | Frozen cycles | |||||||
|---|---|---|---|---|---|---|---|---|
| Study group N = 1196 |
Control group N = 1576 |
P value | t/x2 value | Study group N = 1275 |
Control group N = 2173 |
P value | t/x2 value | |
| Age | 29.5 ± 3.9 | 29.8 ± 4.2 | 0.031* | −2.16 | 30.7 ± 4.9 | 30.2 ± 4.8 | 0.001* | 3.20 |
| <35 | 1094 (91.5) | 1406 (89.2) | 0.061 | 3.47 | 913 (71.6) | 1586 (73.0) | 0.698 | 0.70 |
| ≥35 | 102 (8.5) | 117 (10.8) | 362 (28.4) | 587 (27.0) | ||||
| BMI | 22.9 ± 3.0 | 23.0 ± 3.1 | 0.15 | −1.45 | 23.0 ± 2.5 | 22.8 ± 2.3 | 0.016* | 2.42 |
| Infertile year | 1.8 ± 1.3 | 1.8 ± 1.8 | 0.86 | 0.18 | 2.5 ± 1.5 | 2.7 ± 1.5 | 0.001* | 3.23 |
| Cause of infertility | 0.314 | 1.01 | 0.177 | 0.82 | ||||
| Tubal factor | 788 (65.9) | 1067 (67.7) | 826 (64.8) | 1458 (67.1) | ||||
| Male factor | 408 (34.1) | 509 (32.3) | 449 (35.2) | 715 (32.9) | ||||
| Current cycle | 1.4 ± 0.7 | 1.4 ± 1.1 | 0.96 | 0.055 | 2.4 ± 1.8 | 2.4 ± 1.6 | 0.194 | 1.30 |
| bFSH | 7.0 ± 2.2 | 7.0 ± 3.7 | 0.84 | −0.21 | 7.9 ± 2.6 | 7.7 ± 1.8 | 0.057 | 1.91 |
| bE2 | 37.1 ± 8.9 | 36.5 ± 9.1 | 0.101 | 1.64 | 48.7 ± 16.0 | 49.5 ± 12.4 | 0.146 | −1.45 |
| bLH | 4.6 ± 3.3 | 4.3 ± 2.8 | 0.21 | 1.82 | 4.4 ± 2.5 | 4.3 ± 2.1 | 0.201 | 1.28 |
| PRL | 414.7 ± 178.8 | 402.0 ± 204.8 | 0.089 | 1.703 | 4.9.3 ± 254.9 | 409.9 ± 184.8 | 0.939 | −0.077 |
| AMH | 5.4 ± 0.60 | 5.3 ± 0.67 | 0.029* | 0.089 | 5.1 ± 2.6 | 5.3 ± 2.8 | 0.068 | −1.824 |
| AFC | 15.7 ± 4.4 | 15.5 ± 5.4 | 0.55 | 0.60 | / | / | / | / |
| Number of oocytes retrieved | 10.5 ± 4.5 | 10.6 ± 3.9 | 0.53 | 0.62 | / | / | / | / |
| Number of available embryos | 8.2 ± 1.2 | 8.0 ± 1.6 | 0.01* | 2.57 | / | / | / | / |
| Number of high-quality embryos | 5.1 ± 2.6 | 4.8 ± 2.4 | 0.003* | 2.95 | / | / | / | / |
| embryo stage | 0.000* | 126.4 | 0.01* | 6.57 | ||||
| cleavage-stage embryo | 1015 (84.9) | 1040 (66.0) | 874 (68.5) | 1395 (64.2) | ||||
| blastocyst | 181 (15.1) | 536 (34.0) | 401 (31.4) | 778 (35.8) | ||||
| endometrial thickness at the day of transplantation | 11.6 ± 1.3 | 11.7 ± 1.1 | 0.002* | −3.1 | 10.3 ± 1.9 | 10.2 ± 1.5 | 0.091 | 1.69 |
| mode of delivery | 0.000* | 67.0 | 0.000* | 210.9 | ||||
| cesarean section | 766 (64.0) | 1233 (78.2) | 851 (66.7) | 1899 (87.4) | ||||
| vaginal delivery | 430 (36.0) | 343 (21.8) | 424 (33.3) | 274 (12.6) | ||||
*p < 0.05 was statistically significant