Why wont an embryo attach?

An embryo may fail to attach to the uterine lining for several reasons, including poor embryo quality, hormonal imbalances, or an unsuitable uterine environment. Factors such as uterine abnormalities, inflammation, or insufficient blood supply can also impede implantation. Additionally, genetic issues in the embryo may lead to its inability to properly develop and attach. Overall, a combination of biological and environmental factors plays a critical role in successful implantation.