For instance, there is increased expression of immunoglobulins IgM, IgA, and IgG in patients with chronic endometritis (CE) and RIF [44], and significantly higher levels of the proinflammatory cytokines interleukin 6 (IL-6), proIL-1β, and IL-1β occur among patients with endometriosis [45,46]. Here, IL6 is linked to chronic endometritis.