Objective. To study the specific features of immunity in pregnant women at high risk for postpartum infectious and inflammatory diseases and to further examine the structure of their myometrial biopsy specimens taken during cesarean section. Subjects and methods. A study group comprised 317 pregnant women at high risk for postpartum infectious and inflammatory diseases. A control group included 30 apparently healthy pregnant women. The composition of lymphocyte subpopulations was determined and cytokines were studied in 53 pregnant women in the third trimester. Morphological examination of placental portions was made in 90 pregnant women of the study group. During elective cesarean section, myometrial biopsy specimens were taken from 6 study group patients and from 3 control patients to perform morphological and immunohistochemical studies. Results. Examination of the immune system revealed anti-infection defense changes and signs of an inadequate antiviral response in the pregnant women of the study group. Analysis of the myometrial biopsy specimens in the patients of this group showed the areas of muscle fiber dystrophy and destruction, which were untypical for the control group, and more connective tissue enlargement. Immunohistochemical study of the myometrium with verification of T lymphocytes demonstrated their increase in the study group and their infiltrate-like location between and within the myometrial layers, as well as a reduction in the count of CD68-positive cells. That of actin supported that there was a significant difference between the groups. Conclusion. The study group exhibited enhanced cellular immunological responsiveness with decreased nonspecific reaction to damage.