Table 1.
Baseline characteristics of trial participants (intention-to-treat analysis)
| Characteristics | Blastocyst-stage embryo transfer group (n = 497) | Cleavage-stage embryo transfer group (n = 495) |
|---|---|---|
| Female age, mean (SD), years | 29.6 (3.6) | 29.9 (3.5) |
| Female age, No. (%) | ||
| ≤30 years | 318 (64.0) | 296 (59.8) |
| 30–35 years | 150 (30.2) | 160 (32.3) |
| >35 years | 29 (5.8) | 39 (7.9) |
| Body mass index, mean (SD)a | 22.9 (3.3) | 22.8 (3.2) |
| Duration of attempt to conceive, mean (SD), years | 3.4 (2.3) | 3.5 (2.2) |
| Primary infertility, No. (%) | 255 (51.3) | 239 (48.3) |
| Number of previous IVF or ICSI cycles, No. (%) | ||
| 0 | 466 (93.8) | 449 (90.7) |
| 1 | 31 (6.2) | 46 (9.3) |
| IVF indication, No. (%) | ||
| Tubal factor | 249 (50.1) | 233 (47.1) |
| Male factor | 75 (15.1) | 79 (16.0) |
| Ovulatory dysfunction | 46 (9.3) | 32 (6.5) |
| Endometriosis | 11 (2.2) | 23 (4.6) |
| Unexplained | 27 (5.4) | 32 (6.5) |
| Combined factors | 86 (17.3) | 95 (19.2) |
| Other | 3 (0.6) | 1 (0.2) |
| Antral follicle count in both ovaries, mean (SD) | 18.0 (6.4) | 17.7 (6.9) |
| Follicle-stimulating hormone, mean (SD) [No.], IU/L | 6.6 (1.9) [495] | 6.6 (2.0) [493] |
| Luteinizing hormone, mean (SD) [No.], IU/L | 5.9 (3.8) [496] | 5.7 (3.9) [493] |
| Estradiol, mean (SD) [No.], pg/mL | 45.8 (33.8) [496] | 42.6 (28.8) [493] |
| Anti-Müllerian Hormone, mean (SD) [No.], ng/mL | 5.6 (3.9) [470] | 5.5 (3.9) [467] |
IVF in-vitro fertilization, ICSI intracytoplasmic sperm injection, SD standard deviation.
aCalculated as weight in kilograms divided by the square of the height in meters.