Table 1.
Baseline characteristics of participants in the three cycles.
| Characteristic | NC (n = 4306) | HRT (n = 1007) | GnRH-a+HRT (n = 846) | P | |
|---|---|---|---|---|---|
| Age at embryo transfer (y) | 34.0 (31.0, 37.0) |
34.0 (31.0, 37.0) |
34.0 (31.0, 37.0) |
0.954 | |
| Age at oocyte retrieval (y) | 32.2 (28.8, 35.8) |
32.8 (28.8, 35.9) |
32.5 (29.0, 35.8) |
0.052 | |
| BMI (kg/m2) | 21.9 (20.4, 23.6) |
22.2 (20.8, 23.6)* |
22.0 (20.4, 23.8) |
0.004 | |
| Infertility duration (years) | 3 (2, 5) | 4 (2, 6)* | 4 (3, 6)* | <0.001 | |
| Cause of infertility | |||||
| Male factors | 720/4306 (16.7%) | 119/1007 (11.8%)* | 96/846 (11.3%)* | <0.001 | |
| Tubal factors | 3611/4306 (83.9%) | 904/1007 (89.8%)* | 756/846 (89.4%)* | <0.001 | |
| PCOS+ ovulatory dysfunction | 226/4306 (5.25%) | 140/1007 (13.9%)* | 159/846 (18.8%)*# | <0.001 | |
| Endometriosis | 142/4306 (3.30%) |
34/1007 (3.38%) |
109/846*# (12.9%) |
<0.001 | |
| Uterine malformation | 165/4306 (3.83%) |
45/1007 (4.47%) | 43/846 (5.08%) | 0.201 | |
| Duration of cryopreservation (y) | 0.5 (0.2, 3.3) |
0.3 (0.2, 2.5)* |
0.5 (0.3, 2.8)# |
<0.001 | |
*Compared to the NC, P < 0.05; # = compared to the HRT cycle, P < 0.05; NC, natural cycle; HRT, hormone replacement therapy; GnRH-a, gonadotropin-releasing hormone agonist; PCOS, polycystic ovary syndrome.