Aim. To evaluate changes in immunity in the second trimester of pregnancy in women with exacerbation of bronchial asthma associated with reactivation of cytomegalovirus infection (CMVI).Materials and methods. The concentration of secretory immunoglobulin A (sIgA), immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin M (IgM) and circulating immune complexes (CIC) was studied in 112 women at 21-24 weeks of uncomplicated pregnancy and pregnancy complicated by exacerbation of mild-to-moderate asthma associated with CMVI. The first group included 30 women seronegative for CMV, with an uncomplicated pregnancy. The second group consisted of 30 patients with exacerbation of mild asthma, initiated by the acute phase of CMVI, which induces the development of chronic compensated placental insufficiency. The third group consisted of 27 patients with moderate asthma in the acute stage against the background of the acute phase of CMVI, leading to the formation of chronic compensated placental insufficiency. The fourth group included 25 patients with exacerbation of moderate asthma with CMV etiology, initiating the development of chronic subcompensated placental insufficiency.Results. In women of the second group, the concentration of sIgA was 5.91±0.371 mg/L, IgA – 2.64±0.089 mg/mL, IgG – 15.4±0.791 mg/mL, IgM – 2.32±0.144 mg/mL, CIC – 0.176±0.004 optical density units (in the first group, respectively, 4.31±0.266 mg/L, p<0.001; 2.37±0.06 mg/mL, p<0.05; 13.3±0.293 mg/mL, p<0,05; 1.11±0.06 mg/mL, p<0.001; 0.092±0.005 optical density units, p<0.001). In patients of the third group, in contrast to the second one, no differences in immunity parameters were detected. In the fourth group, in comparison with the third one, lower parameters of sIgA (3.21±0.213 mg/L, p<0.001), IgA (1.43±0.081 mg/mL, p<0.001), as well as higher IgG values were detected (19.8±0.418 mg/mL, p<0.001), IgM (2.94±0.082 mg/mL, p<0.01) and CIC (0.198±0.005 optical density units, p<0.05).Conclusion. In patients with moderate asthma with exacerbation against the background of CMVI reactivation, which initiates the formation of chronic subcompensated placental insufficiency, in contrast to women with moderate asthma in the stage of CMVI exacerbation in the second trimester of pregnancy, leading to chronic compensated placental insufficiency in the third trimester of gestation, a more pronounced imbalance of humoral immunity and autoimmune disorders are found, which are important in the development of chronic placental dysfunction.