Chronic endometritis is the most common endometrial pathology in women with habitual miscarriage. Urogenital infections, persistence of pathogenic and opportunistic flora lead to chronic inflammatory process in the endometrium and secondary immunodeficiency states. In the endometrium, an increased number of NK- (CD16+ and CD56+), В- (CD20+) lymphocytes and cells expressing the late HLA-DR activation marker are determined. These lymphocytes enhance the expression of histocompatibility antigens by endometrial cells and lead to autoimmune inflammation. The imbalance between immune tolerance to the fetus and immune activation to the pathogenic organisms is associated with poor pregnancy outcomes. After a course of complex therapy of chronic endometritis, most women with miscarriage can only reduce the severity of the inflammatory process in the endometrium. The aim of this study was to assess the importance of immunomodulatory effects of human immunoglobulin during pregnancy in women with miscarriage. The study included 182 patients with a history of miscarriage and chronic endometritis. Group 1 consisted of 98 women who received an intravenous course of human immunoglobulin at 7/8 weeks of pregnancy. Group 2 comprised 84 pregnant women who did not receive immunoglobulin therapy. An analysis of the results of the course and outcomes of pregnancy showed that administering an intravenous immunoglobulin course to pregnant women with miscarriage and chronic endometritis in the history prior to the first wave of trophoblast invasion helps to reduce the frequency of threatened abortion (54% in group 1 and 95% in group 2, p < 0.001). The data obtained suggest that intravenous immunoglobulin should be recommended for women with habitual miscarriage and chronic endometritis during pregnancy up to 8 weeks.