The Impact of Endometriosis on Fertility

Background Endometriosis, an enigmatic progressive and estrogen-dependent disease characterized by development of endometrial tissue outside of the uterus, causes pain and infertility on reproductive-aged women [1–4]. The healthrelated quality of the afflicted women’s life is seriously decreased due to chronic pelvic pain and subfertility. Endometriosis was first described by Sampson in 1921 [5]. Although the exact prevalence of endometriosis is not well known, it was speculated as 10% of reproductive-aged women. However, a recent epidemiologic study has shown that the prevalence of endometriosis is 1.5% [6]. The prevalence of endometriosis asymptomatic parous women who underwent laparoscopy due to tubal ligation or other benign pelvic pathology had been reached to approximately 40% [7]. However, the prevalence of endometriosis in infertile women has been reported as 9–50% [2–4]. This severity of disease increases by older age due to progression of endometriosis. The advanced stages of endometriosis lead to the lesser fecundity. Although the prevalence of endometriosis in infertile women seemed to be nearly 50%, all women with endometriosis are not infertile actually. Women diagnosed to have endometrioma by ultrasonography may still achieve a spontaneous pregnancy. Hence, endometriosis is not a direct cause of infertility. Monthly fecundity rates drop from 25% to 2–10% in endometriosis [8]. Endometriosis has associations with infertility; however, the exact mechanisms are yet to be defined and scientific evidence has not completely established. The poor pregnancy outcomes in endometriosis patients were linked to reduced ovarian reserve, low numbers of oocytes retrieved, lower oocyte and embryo quality, impairment of implantation associated with reduced endometrial receptivity, especially in severe endometriosis, although contradicting reports suggest similar results with control cases. Live birth rates in women with endometriosis are comparable to women with other causes in the SART reports [9]. Additionally, adverse pregnancy outcomes, such as pregnancy loss, preterm delivery, pre-eclampsia and intrauterine growth restriction, have been demonstrated to occur more frequently in subjects with endometriosis [10,11].