Adenomyosis is a condition in which the cells of endometrium (the uterine lining) are present inside the muscular wall of uterus. There is also associated hypertrophy uterine muscles.
Adenomyosis can affect fertility in two ways. Firstly it effects the uterine contractions which helps sperms to reach the tubes. Secondly it also increases the number of toxic cells in the uterine lining which may effect the implantation of embryos.
Adenomyosis may also be associated with endometriosis, a condition in which the uterine lining cells are present in the ovaries or other sites in pelvic. This may further effect the oocyte quality and number, further contributing to difficulty in conception.