Placental Histopathological Changes and the Level of Anti-Spike Antibody After Covid-19 Vaccination During Pregnancy: A Case Series.

Background: COVID-19 infection during pregnancy could be associated with placental histopathological changes such as vascular diseases and malperfusion. There are studies showing that mRNA vaccines are not associated with significant placental pathological changes. Our objective was to evaluate the placental histopathology in pregnant women who received Sinopharm, an inactivated virus vaccine, during pregnancy. Case Presentation: The study included placental samples collected from mothers who gave birth of living singletons through elective cesarean sections performed between March 2022 and May 2022 at Imam Khomeini Hospital Complex. The study included women who had no history of positive reverse transcription polymerase chain reaction (RT-PCR) testing for COVID-19 during pregnancy, and had received at least one dose of COVID-19 vaccine during their pregnancy. Humoral levels of anti-SARS-CoV-2 spike IgG were measured in both the mothers and neonates. Results: The study included 20 mother-neonate pairs. The mean maternal age was 34±3.6 years, and all mothers received Sinopharm vaccine as their first and second doses. The last vaccine dose was administered during pregnancy, with 3 mothers receiving it in the first trimester, 9 in the second trimester, and 8 in the third trimester. The histopathological findings in the placental samples included decidual vasculopathy, subchorionic thrombosis, and chronic histiocytic intervillositis. All mothers and neonates, except one pair, were positive for anti-spike antibody. Conclusion: Multiple abnormal histopathological findings were reported in placenta of vaccinated mothers. However, similar to previous studies, these placental findings are considered mild lesions and have been observed in both vaccinated and unvaccinated mothers.