SARS-CoV-2(37) Placenta(37) Pregnancy(33) placental(30) COVID-19(30) fetal(21) SARS-COV-2 infection(19) antibody(17) Placentas(17) pathology(15) Infection(15) positive(15) Maternal(13) Infant(13) coronavirus(13) acute respiratory syndrome(13) pregnant women(13) ACE2(12) expression(12) performed(12) Vascular(12) evaluate(12) age(12) receptor(11) prospective cohort study(11) vertical transmission(11) mother(11) moderate(11) histologic(10) Neonatal(10)