Pregnant women are at increased risk of COVID-19. This could be explained through the prism of physiologic and immunologic changes in pregnancy. In addition, certain immunological reactions originate in the placenta in response to viral infections. This study aimed to investigate whether SARS-CoV-2 can infect the human placenta and discuss its implications in the pathogenesis of adverse pregnancy outcomes. We conducted a retrospective cohort study in which we collected placental specimens from pregnant women who had a laboratory-confirmed SARS-CoV-2 infection. We performed RNA in situ hybridization (RNA-ISH) assay on formalin-fixed paraffin-embedded (FFPE) tissues to establish the in vivo evidence for placental infectivity by this corona virus. In addition, we infected trophoblast isolated from uninfected term human placenta with SARS-CoV-2 variants to further provide in vitro evidence for such an infectivity. There was a total of 21 cases enrolled, which included five cases of spontaneous preterm birth (SPTB) and two intrauterine fetal demises (IUFDs). Positive staining of positive-sense strand (PSS) of SARS-CoV-2 virions was detected in 15 placentas including four SPTB and both IUFDs. In vitro infection assay demonstrated that SARS-CoV-2 virions were highly capable of infecting both cytotrophoblast and syncytiotrophoblast. This study implies that placental SARS-CoV-2 infection may be associated with an increased risk of adverse obstetrical outcomes.