Table 1.
Demographic and cycle characteristics of patients between immediate and delayed groups stratified by COS protocol
| GnRHa protocol | GnRHant protocol | |||||
|---|---|---|---|---|---|---|
| Immediate FET (n = 1585) |
Delayed FET (n = 1525) |
P value | Immediate FET (n = 778) |
Delayed FET (n = 516) |
P value | |
| Age (years) | 31.74 ± 4.33 | 31.98 ± 4.23 | 0.113 | 31.37 ± 4.03 | 31.53 ± 4.23 | 0.190 |
| BMI (kg/m2) | 21.51 ± 3.01 | 21.43 ± 2.83 | 0.407 | 21.49 ± 2.83 | 21.36 ± 2.81 | 0.227 |
| Type of infertility | 0.062 | 0.606 | ||||
| Primary infertility | 46.6 (738/1585) | 49.9 (761/1525) | 55.5 (432/778) | 54.1 (279/516) | ||
| Secondary infertility | 53.4 (847/1585) | 50.1 (764/1525) | 44.5 (346/778) | 45.9 (237/516) | ||
| Infertility duration (years) | 4.38 ± 2.95 | 4.45 ± 3.03 | 0.857 | 4.20 ± 2.83 | 4.39 ± 2.89 | 0.236 |
| AMH (ng/ml) | 3.17 ± 1.51 | 3.20 ± 1.12 | 0.324 | 3.34 ± 1.50 | 3.29 ± 1.63 | 0.788 |
| FSH (mIU/ml) | 5.45 ± 1.71 | 5.32 ± 1.78 | 0.269 | 5.31 ± 1.65 | 5.43 ± 1.69 | 0.309 |
| LH (mIU/ml) | 3.75 ± 1.57 | 3.67 ± 1.48 | 0.859 | 3.82 ± 1.58 | 3.77 ± 1.69 | 0.808 |
| E2 (pmol/ml) | 132.01 ± 48.75 | 135.71 ± 48.26 | 0.660 | 134.19 ± 49.67 | 131.77 ± 58.33 | 0.970 |
| Reasons of infertility | 0.424 | 0.321 | ||||
| Female factor | 50.3 (798/1585) | 52.9 (806/1525) | 47.6 (370/778) | 51.7 (267/516) | ||
| Male factor | 19.2 (305/1585) | 19.3 (295/1525) | 13.1 (102/778) | 13.8 (71/516) | ||
| Multiple factors | 28.0 (444/1585) | 25.7 (392/1525) | 38.6 (300/778) | 33.5 (173/516) | ||
| Unexplained infertility | 2.4 (38/1585) | 2.1 (32/1525) | 0.8 (6/778) | 1.0 (5/516) | ||
| No. of oocytes retrieved | 15.81 ± 5.36 | 15.89 ± 5.43 | 0.709 | 15.63 ± 5.96 | 15.10 ± 6.40 | 0.328 |
| Fertilization method | 0.248 | 0.304 | ||||
| IVF | 84.3 (1336/1585) | 82.8 (1262/1585) | 83.4 (649/778) | 81.2 (419/778) | ||
| ICSI | 15.7 (249/1585) | 17.2 (263/1585) | 16.6 (129/778) | 18.8 (97/778) | ||
| Endometrial thickness on day of FET decision (mm) | 9.14 ± 1.62 | 8.93 ± 1.65 | 0.001 | 8.79 ± 1.57 | 8.68 ± 1.67 | 0.234 |
| No. of embryos transferred | 1.80 ± 0.40 | 1.81 ± 0.40 | 0.713 | 1.68 ± 0.47 | 1.69 ± 0.46 | 0.652 |
| Embryo developmental stage at transfer | 0.463 | 0.064 | ||||
| Day 3 embryo | 26.3 (417/1585) | 28.5 (435/1525) | 23.4 (182/778) | 28.1 (145/516) | ||
| Day 4embryo | 3.5 (56/1585) | 3.8 (58/1525) | 3.3 (26/778) | 3.1 (16/516) | ||
| Day 5embryo | 57.0 (903/1585) | 54.3 (828/1525) | 60.5 (471/778) | 60.1 (310/516) | ||
| Day 6 embryo | 13.2 (209/1585) | 13.4 (204/1525) | 12.7 (99/778) | 8.7 (45/516) | ||
| Endometrial preparation | 0.131 | 0.271 | ||||
| Natural | 13.8 (218/1585) | 15.7 (239/1525) | 17.4 (135/778) | 19.8 (102/516) | ||
| Programmed | 86.2 (1367/1585) | 84.3 (1286/1525) | 82.6 (643/778) | 80.2 (414/516) | ||
| Survival rate | 97.9 (3136/3203) | 97.7 (3237/3313) | 0.520 | 98.2 (1448/1474) | 98.5 (972/987) | 0.643 |