Clinical-pathological features in placentas of pregnancies with SARS-CoV-2 infection and adverse outcome: case series with and without congenital transmission

Objective To correlate clinical outcomes to pathology in SARS-CoV-2 infected placentas in stillborn and live-born infants presenting with fetal distress. Design Retrospective, observational. Setting Nationwide. Population Five stillborn and nine live-born infants from 13 pregnant women infected with SARS-CoV-2 seeking care at seven different maternity units in Sweden. Methods Clinical outcomes and placental pathology were studied in 14 cases (one twin pregnancy) of maternal SARS-CoV-2 infection with impaired fetal outcome. Outcomes were correlated to placental pathology in order to investigate the impact of virus-related pathology on the villous capillary endothelium, trophoblast and other cells. Main outcome measures Maternal and fetal clinical outcomes and placental pathology in stillborn and live-born infants. Results Reduced fetal movements were reported (77%) and time from onset of maternal COVID-19 symptoms to signs of fetal distress among live-born infants was 6 (3-12) days and to diagnosis of stillbirth 11 (2-25) days. Two of the live-born infants died during the postnatal period. Signs of fetal distress led to emergency caesarean section in all live-born infants with umbilical cord blood gases and low Apgar scores confirming intrauterine hypoxia. Five stillborn and one live-born neonate had confirmed congenital transmission. Massive perivillous fibrinoid deposition, intervillositis and trophoblast necrosis were associated with SARS-CoV-2 placental infection and congenital transmission. Conclusions SARS-CoV-2 can cause rapid placental dysfunction with subsequent acute fetal hypoxia leading to intrauterine fetal compromise. Associated placental pathology included massive perivillous fibrinoid deposition, intervillositis and trophoblast degeneration.