Endometriosis and infertility
Surgery is more effective for infertility than medicinal intervention in endometriosis. One study has shown that surgical treatment of endometriosis approximately doubles the fecundity (pregnancy rate). The use of medical suppression after surgery for minimal/mild endometriosis has not shown benefits for patients with infertility. Use of fertility medication that stimulates ovulation (clomiphene citrate, gonadotropins) combined with intrauterine insemination (IUI) enhances fertility in these patients.
Endometrium
The endometrial lining undergoes cyclic regeneration. Humans, apes, and some other species display the menstrual cycle, whereas most other mammals are subject to an estrous cycle. In both cases, the endometrium initially proliferates under the influence of estrogen. However, once ovulation occurs, the ovary (specifically the corpus luteum) will produce much larger amounts of progesterone. This changes the proliferative pattern of the endometrium to a secretory lining. Eventually, the secretory lining provides a hospitable environment for one or more blastocysts.