Immune response to SARS-CoV-2 infection during pregnancy and the possible outcomes on fetal and neonatal health have not been well established. Peripheral levels of total T lymphocytes, CD4+, CD8+, B lymphocytes and natural killer cells in pregnant and postpartum women with positive and negative PCR for SARS-CoV-2 were determined with the purpose of identifying changes that could compromise fetal and neonatal health. Peripheral blood samples from women who underwent PCR for the diagnosis of COVID-19 between May 2021 and March 2022 were analyzed by flow cytometry using the FACScan and Cell Quest software. The sample consisted of 50 women, of which 32 (64%) tested positive for COVID-19. Pregnant and postpartum women with COVID-19 had high levels of (CD3+/8+) cells, contrary to what was observed for (CD16-56+) and (CD19+) cells that had low counts in the group with less than 30 days of infection. Additionally, elevated total T cell counts were also observed in women vaccinated with one or two doses of the SARS-CoV-2 vaccine. Pregnant and postpartum women with COVID-19 have a higher number of cytotoxic T lymphocytes in their peripheral blood and a lower number of NK cells and B lymphocytes. Low blood levels of B cells may result in less transplacental transfer of IgG antibodies to the fetus, which may result in greater risk of infection. Further studies are necessary to elucidate the changes caused by COVID-19 in the immune system of these women and to comprehend whether these changes have the potential to compromise fetal and neonatal development.