BACKGROUND Immunosuppressive treatment in pregnant organ recipients can affect functions of the fetal and newborn immune system. The aim of this study was to evaluate the effect of this treatment on selected parameters of the immune system of children born to mothers after liver transplantation. MATERIAL AND METHODS The study included 52 children born to liver recipients and 52 children in the control group. The study was conducted in the 1st Department of Obstetrics and Gynecology, Medical University of Warsaw. Children from the 1st day of life to 10 years of age were examined. Serum antibody concentrations of IgG, IgM, and IgA were measured by the immune agglutination method on a Cobas 6000 analyzer. RESULTS Comparison of mean IgG, IgM, and IgA levels and with reference values did not show a significant difference between the study and control group (p>0.05). Immunoglobulin concentrations were also analyzed in the groups of children according to their age at the time of the test and the type of calcineurin inhibitor used in the mother's treatment. The analysis showed a significant difference in the distribution of IgA concentrations in comparison to the normal values (p<0.05), as well as mean IgA (p<0.05) and IgM concentrations (p<0.05) according to the type of immunosuppressive treatment of the mother (tacrolimus or cyclosporin treatment regimen). CONCLUSIONS Analysis of the type of immunosuppressive therapy used during pregnancy revealed a possible influence of the type of calcineurin inhibitor on selected parameters of the immune system of the children; however, further research is needed to confirm these findings.