What would be a reason for a fertilized egg to not be able to implant in the uterus?

Good question: Well, there are a variety of reasons a fertilized egg may not implant. In fact, i was taught in medical school that an estimated 50% of all fertilized eggs are "spontaneously aborted"- meaning your body naturally rejects them. It is thought that this is because of genetic malformations that the body is capable of recognizing early as incompatible or not advantageous to life. Scarring can also caus.