| Table 1. Comparison of pregnancy and multiple pregnancy rates when only high-quality embryos or a high-quality and an extra low-quality embryo were transferred on day three or five of development for patients <36y-old or ≥ 36 y-old. | |||||
| Patient’s Age | Embryo Transfer | Parameter | High-Quality Group | High-and-Low Quality Group | P |
| <36y-old | Day three | Pregnancy | 35.9 (64/178) | 35.6 (46/129) | 0.823 |
| Multiple Pregnancy | 17.1 (11/64) | 28.2 (13/46) | 0.020 | ||
| Day Five | Pregnancy | 36.0 (90/250) | 42.4 (59/139) | <0.001 | |
| Multiple Pregnancy | 4.4 (4/90) | 16.9 (10/59) | <0.001 | ||
| ≥ 36 y-old | Day three | Pregnancy | 31.0 (115/370) | 31.9 (53/166) | 0.830 |
| Multiple Pregnancy | 18.2 (21/115) | 26.4 (14/53) | 0.049 | ||
| Day Five | Pregnancy | 31.6 (57/180) | 36.9 (31/84) | 0.247 | |
| Multiple Pregnancy | 5.2 (3/57) | 16.1 (5/31) | <0.001 | ||