Placental pathology, neonatal birth weight, and Apgar score in acute and distant SARS-CoV-2 infection

Most research on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection during pregnancy has been on acute infections with limited data on the effect of distant infection.

We examined placental pathology and neonatal outcomes in distant SARS-CoV-2 infection earlier in pregnancy compared to acute infections late in pregnancy/at birth and to non-SARS-CoV-2 infected patients with other placental pathologies/clinical presentations.

Placentas birthed to unvaccinated patients with SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) testing and serology testing results from time of delivery were included in this study. A total of 514 singleton placentas between April 18, 2020, and July 26, 2021, were included: 77 acute SARS-CoV-2 infection (RT-PCR positive and serology negative); 222 distant SARS-CoV-2 infection (RT-PCR negative but serology IgG-positive); and 215 non-SARS-Cov-2 infected (RT-PCR negative, serology negative, and history negative) with other placental pathologies: preeclampsia/hypertension, intrauterine growth restriction (IUGR), diabetes, chorioamnionitis, and meconium. Placental pathology findings, Apgar scores, and neonatal birth weights were compared.

Placentas from the acute group had significantly more villous agglutination (10.4%, P = 0.015) and eosinophilic T-cell vasculitis (5.2%, P = 0.004) compared to placentas from the distant group (2.7% and 0%) and non-SARS-CoV-2 placentas (1.9% and 0.9%). One acute case showed SARS-CoV-2 placentitis and resulted in preterm delivery at 25 weeks. Both the preeclampsia/hypertension and the IUGR groups showed significantly more maternal vascular malperfusion findings compared to the acute (6.5%, 6.5% and 1.3%) and distant (7.7%, 7.7%, and 3.2%) groups. Fetal vascular malperfusion findings such as thrombosis of fetal vessels (17.4% P = 0.042) and intramural fibrin deposition (21.7% P = 0.026) were significantly higher in the IUGR group compared to acute (7.8%; 2.6%) and distant (3.6%; 8.1%) infection. Many neonates born to patients infected with SARS-CoV-2 had birth weights outside of 95% confidence range of observed birth weights. There was no association of Apgar scores with infection status or placental pathology.

Acute and distant SARS-CoV-2 infections present differing placental pathology.

SARS-CoV-2 infection during pregnancy has demonstrable effects on the placenta with potential significant impacts for maternal and fetal health. Prevention of maternal SARS-CoV-2 infection, primarily through vaccination, remains the best mitigation strategy to prevent sequelae of maternal SARS-CoV-2 infection.