2.5.1. Primary endpoint.
The primary endpoint is the presence of clinical pregnancy 3 weeks after in vitro fertilization/ET treatment (V4). Clinical pregnancy is diagnosed by confirmation of the fetal sac through endovaginal ultrasonography. When the fetal sac cannot be confirmed, another ultrasound examination is performed 1 week later (V5). If the fetal sac is identified at that time, clinical pregnancy is diagnosed.