Intrauterine transmission of the Chikungunya virus (CHIKV) during early pregnancy has rarely been reported, although vertical transmission has been observed in newborns. Here, we report four cases of spontaneous abortion in women who became infected with CHIKV between the 11th and 17th weeks of pregnancy. Laboratorial confirmation of the infection was conducted by RT-PCR on a urine sample for one case, and the other three were by detection of IgM anti-CHIKV antibodies. Hematoxylin and eosin (H&E) staining and an electron microscopy assay allowed us to find histopathological, such as inflammatory infiltrate in the decidua and chorionic villi, as well as areas of calcification, edema and the deposition of fibrinoid material, and ultrastructural changes, such as mitochondria with fewer cristae and ruptured membranes, endoplasmic reticulum with dilated cisterns, dispersed chromatin in the nuclei and the presence of an apoptotic body in case 1. In addition, by immunohistochemistry (IHC), we found a positivity for the anti-CHIKV antibody in cells of the endometrial glands, decidual cells, syncytiotrophoblasts, cytotrophoblasts, Hofbauer cells and decidual macrophages. Electron microscopy also helped in identifying virus-like particles in the aborted material with a diameter of 40–50 nm, which was consistent with the size of CHIKV particles in the literature. Our findings in this study suggest early maternal fetal transmission, adding more evidence on the role of CHIKV in fetal death.

Understanding perinatal health outcomes following SARS-CoV-2 infection during pregnancy necessitates large-scale studies of mother-infant dyads. Hospital-based studies of pregnant women and their neonates provide valuable insights within the field of perinatal health research. The aim of this study was to evaluate the effect of SARS-CoV-2 infection on maternal and perinatal outcomes among hospitalized pregnant women in Rio de Janeiro during the COVID-19 pandemic. Methods: The study consisted of a time-to-event analysis of a hospital-based cohort of 1185 pregnant women ≥ 16 years and their infants from May 2020 to March 2022. Pregnant women were classified as infected if they had a SARS CoV-2 positive RT-PCR or a positive rapid antigen test. An exploratory analysis of qualitative variables was conducted with calculation of absolute and relative frequencies and calculation of 95% confidence intervals. Survival functions were estimated by the Kaplan–Meier method, and the Cox proportional hazards model was employed to interpret the effects of SARS-CoV-2 infection on time to adverse maternal and perinatal outcomes, adjusted for vaccination, comorbidity, and gestational trimester. Results: A total of 21% (249/1185) women were infected with SARS-CoV-2, with a median age of 26 (range: 16–47). Cesarean section deliveries were performed in 57% (135/237) SARS CoV-2+ participants vs. 43% (391/914) of uninfected participants, p < 0.001. Intensive care unit admission and/or death occurred in 68 of 1185 participants (5.7%), 44 of 249 participants (17.7%) infected with SARS CoV-2 vs. 24 of 936 uninfected participants (2.5%). All 21 participants who died were unvaccinated against COVID-19. Women infected with SARS-CoV-2 were at greater risk of adverse maternal outcomes (crude HR: 5.93, 95% CI: 3.58–9.84; adjusted HR: 5.47, 95% CI: 3.16–9.48) than uninfected pregnant women. SARS CoV-2 vertical transmission was observed in 6 of 169 (3.6%) tested neonates. Preterm deliveries occurred more frequently in patients testing positive for SARS-CoV-2 (30.7% vs. 23.6). In the survival analysis, no effect of SARS-CoV-2 infection was observed on prematurity (HR: 0.92, 95% CI: 0.68–1.23) and adverse perinatal outcomes, including fetal distress (HR: 1.29, 95% CI: 0.82–2.05), stillbirth (HR: 1.07, 95% CI: 0.48–2.38), and neonatal death (HR: 0.96, 95% CI: 0.35–2.67), even after adjusting for vaccination, comorbidity, gestational trimester, and periods of time. Conclusion: The risk of maternal death due to COVID-19 highlights the need for adequate preventive measures, particularly vaccination, during the prenatal and postpartum periods.