Table 5.
Baseline characteristic of cycles with storage time ≤1 year and >5 years before and after matching.
| storage time | unmatched | matched | ||||
|---|---|---|---|---|---|---|
| ≤1 y | >5 y | p value | ≤1 y | >5 y | p value | |
| number of cycles, n | 8391 | 172 | 171 | 171 | ||
| maternal age at OPU, median (IQR) | 32 (28~36) | 28 (26~30) | <0.001 | 28 (26~30) | 28 (26~30) | 0.674 |
| maternal BMI, median (IQR) | 21.5 (19.8~23.6) | 21.0 (19.8~23.2) | 0.207 | 21.0 (19.5~23.4) | 21.0 (19.8~23.2) | 0.829 |
| type of infertility, n (%) | 0.441 | 0.745 | ||||
| primary | 4735 (56.4) | 92 (53.5) | 89 (52.0) | 92 (53.8) | ||
| secondary | 3656 (43.6) | 80 (46.5) | 82 (48.0) | 79 (46.2) | ||
| length of infertility, median (IQR) | 3.0 (2.0~4.5) | 3.0 (2.0~5.0) | 0.014 | 3.0 (2.0~5.0) | 3.0 (2.0~5.0) | 0.853 |
| main etiology, n (%) | 0.227 | 0.686 | ||||
| female factor | 6374 (76.0) | 130 (75.6) | 133 (77.8) | 129 (75.4) | ||
| male factor | 822 (9.8) | 22 (12.8) | 23 (13.5) | 22 (12.9) | ||
| male and female factors | 894 (10.7) | 18 (10.5) | 12 (7.0) | 18 (10.5) | ||
| unexplained | 301 (3.6) | 2 (1.2) | 3 (1.8) | 2 (1.2) | ||
| number of oocytes retrieved, median (IQR) | 12 (7~17) | 17 (12~20) | <0.001 | 17 (12~22) | 17 (12~20) | 0.830 |
| number of previous thawing, n (%) | 0.602 | 0.579 | ||||
| 0 | 7051 (84.0) | 142 (82.6) | 137 (80.1) | 141 (82.5) | ||
| ≥1 | 1340 (16.0) | 30 (17.4) | 34 (19.9) | 30 (17.5) | ||
| development stage of embryo transferred, n (%) | 0.001 | 0.445 | ||||
| cleavage embryo | 1710 (20.4) | 17 (9.9) | 13 (7.6) | 17 (9.9) | ||
| blastocyst | 6681 (79.6) | 155 (90.1) | 158 (92.4) | 154 (90.1) | ||
| endometrial preparation method, n (%) | 0.748 | 0.817 | ||||
| artificial | 7027 (83.7) | 147 (85.5) | 150 (87.7) | 146 (85.4) | ||
| natural | 445 (5.3) | 7 (4.1) | 6 (3.5) | 7 (4.1) | ||
| others | 919 (11.0) | 18 (10.5) | 15 (8.8) | 18 (10.5) | ||
| thickness of endometrium, median (IQR) | 9.1 (8.4~10.0) | 9.0 (8.4~10.0) | 0.737 | 9.1 (8.7~10.2) | 9.0 (8.4~10.0) | 0.174 |
OPU, ovum pick-up; IQR, interquartile range.