| Maternal age at oocyte retrieval, y | 28.2 ± 3.2 | 29.0 ± 3.1 | 0.088 |
| Body mass index (BMI), kg/m2 | 23.4 ± 2.9 | 22.5 ± 3.3 | 0.065 |
| Paternal age, y | 29.4 ± 3.5 | 30.2 ± 3.6 | 0.142 |
| Infertility diagnosis, n (%) | | | 0.611 |
| Tubal factor | 23 (25.3) | 23 (27.7) | |
| Ovulatory disfunction | 22 (24.2) | 13 (15.7) | |
| Diminished ovarian reserve | 1 (1.1) | 2 (2.4) | |
| Male factor | 22 (24.2) | 19 (22.9) | |
| Unknown factor | 23 (25.3) | 26 (31.3) | |
| Fertilization method, n (%) | | | 0.207 |
| IVF | 60 (65.9) | 62 (74.7) | |
| ICSI | 31 (34.1) | 21 (25.3) | |
| Cycle type, n (%) | | | 0.074 |
| Fresh | 36 (39.6) | 45 (54.2) | |
| Frozen | 55 (60.4) | 38 (45.8) | |
| Development days, n (%) | | | 0.575 |
| Day 5 | 75 (82.4) | 71 (85.5) | |
| Day 6 | 16 (17.6) | 12 (14.5) | |
| Expansion degree, n (%) | | | 0.709 |
| 1 | 1 (1.1) | 0 | |
| 2 | 2 (2.2) | 1 (1.2) | |
| 3 | 21 (23.1) | 23 (27.7) | |
| 4 | 62 (68.1) | 57 (68.7) | |
| 5 | 4 (4.4) | 2 (2.4) | |
| 6 | 1 (1.1) | 0 | |
| ICM grade a, n (%) | | | 0.005 |
| A | 24 (26.4) | 39 (47.0) | |
| B | 67 (73.6) | 44 (53.0) | |
| TE grade, n (%) | | | 0.346 |
| A | 14 (15.4) | 12 (14.5) | |
| B | 49 (53.8) | 53 (63.9) | |
| C | 28 (30.8) | 18 (21.7) | |
