Mild endometriosis may have little, if any, impact on fertility. In fact some women may never be aware that they have it. However, more severe endometriosis can have a significant impact on fertility and your ability to fall pregnant. The displaced endometrial tissue can damage to internal organs including the fallopian tubes, ovaries and uterus. Scarring can hinder or block the passage of the egg and sperm making fertilization difficult or impossible. Scarring on the uterus may prevent a fertilized egg from implanting. If endometriosis is present on the ovaries, eggs may be damaged resulting in decreased ovarian reserve and reduced egg quality and quantity. The continual bleeding of displaced endometrial tissue also increases inflammation and congestion within the body.