COVID-19 during pregnancy alters circulating extracellular vesicle cargo and their effects on trophoblast (preprint)

SARS-CoV-2 infection and the resulting coronavirus disease (COVID-19) complicate pregnancies as the result of placental dysfunction which increases the risk of adverse pregnancy outcomes. While abnormal placental pathology resulting from COVID-19 is common, direct infection of the placenta is rare. This suggests maternal response to infection is responsible for placental dysfunction. We hypothesized that maternal circulating extracellular vesicles (EVs) are altered by COVID-19 during pregnancy and contribute to placental dysfunction. To examine this, we characterized maternal circulating EVs from pregnancies complicated by COVID-19 and tested their functional effect on trophoblast cells in vitro. We found the timing of infection is a major determinant of the effect of COVID-19 on circulating EVs. Additionally, we found differentially expressed EV mRNA cargo in COVID-19 groups compared to Controls that regulates the differential gene expression induced by COVID-19 in the placenta. In vitro exposure of trophoblasts to EVs isolated from patients with an active infection, but not EVs isolated from Controls, reduced key trophoblast functions including hormone production and invasion. This demonstrates circulating EVs from subjects with an active infection disrupt vital trophoblast function. This study determined that COVID-19 has a long-lasting effect on circulating EVs and circulating EVs are likely to participate in the placental dysfunction induced by COVID-19.

Global Transcriptomic Analysis of Placenta From Women With Gestational Sars-Cov-2 Infection During the 3rd Trimester of Pregnancy (preprint)

The COVID-19 pandemic has led to a significant and enduring influence on global health, in-cluding maternal and fetal well-being. Evidence suggests that placental dysfunction is a potential consequence of SARS-CoV-2 infection during pregnancy, which may result in adverse outcomes such as preeclampsia and preterm birth. However, the molecular mechanisms underlying this association remain unclear, and it is uncertain whether a mature placenta can protect the fetus from SARS-CoV-2 infection. To address the above hiatus, we conducted a transcriptome-based study of the placenta in both maternal and fetal compartments. We collected placental samples from 16 women, immediately after term delivery, of which seven had confirmed SARS-CoV-2 in-fection by PCR before parturition. Notably, we did not detect any viral load in either the maternal or fetal compartments of the placenta, regardless of symptomatic status. We extracted total RNA from placental tissues, separately from maternal and fetal compartments, constructed cDNA li-braries, and sequenced them to assess mRNA and small RNA expression. Our analysis revealed 727 differentially expressed genes (DEG) in the maternal placental tissue, with 608 upregulated and 109 downregulated in SARS-CoV-2-positive women compared with healthy, negative wom-en. In contrast, the fetal compartment did not exhibit any significant changes in gene expression with SARS-CoV-2 infection. Specifically, we observed significant downregulation of seven genes belonging to the pregnancy-specific glycoprotein (PSG), related to the immunoglobulin superfam-ily in the maternal compartment with active SARS-CoV-2 infection (fold change range from -13.70 to -5.28, FDR ≤ 0.05). Additionally, comparing symptomatic women with healthy, we identified 14,223 DEGs, with high expression of the inflammatory cytokine IL6 in the maternal placenta of the symptomatic women. Furthermore, KEGG analysis revealed that pathways relat-ed to viral infection, vascular smooth muscle contraction, and oxytocin signaling were altered significantly in symptomatic women. Overall, our study sheds light on the molecular mechanisms underlying the reported clinical risk of preeclampsia and preterm delivery in women with SARS-CoV-2 infection. Nonetheless, studies with larger sample sizes are warranted to further deepen our understanding of the molecular mechanisms of the placenta’s anti-viral effects in ma-ternal SARS-CoV-2 infection.

Histomorphological evaluation of placenta in SARS-CoV-2 patients: A cross-sectional study.

Background: SARS-CoV-2 has emerged as a major pandemic of the century and little is known about the impact of maternal infection on placental histopathology. Histopathologic examination of placental tissue can contribute to significant information regarding the pathophysiology of the disease and how it affects the fetal outcome. Materials and Methods: This was a cross-sectional study conducted at the Department of Pathology, Government Doon Medical College and Hospital, Dehradun, on the placenta of 50 coronavirus disease 2019 (COVID-19)-positive pregnant females confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) from August 2020 to October 2020. Fifty term historical placentas were taken as control. Placenta sections were fixed in formalin, processed into paraffin blocks, stained with hematoxylin and eosin (H and E) stain, and visualized for any abnormality. Results: The most prominent histological finding in the placenta of pregnant women affected by COVID-19 was chorangiosis, which is a feature of fetal vascular malperfusion seen in 28 (56%) cases. Other features included maternal vascular malperfusions (MVM) such as villous crowding and agglutination in 12 (24%) cases. Tenney-Parker change was seen in 13 (26%) patients. Intervillous fibrinoid deposition and intervillous hemorrhage were seen in 37 (74%) patients and 7 (14%) patients showed significant calcification. Other findings observed were less common. Conclusion: Infection with SARS-CoV-2 may be associated with a significant impact on fetal and maternal circulation causing features of fetal and maternal malperfusion such as chorangiosis, villous crowding, and agglutination. Indicating that the infection could cause a potential rise in the risk of adverse perinatal outcomes such as intrauterine fetal growth retardation, preterm birth, or stillbirth.

The placental pathology in Coronavirus disease 2019 infected mothers and its impact on pregnancy outcome.

INTRODUCTION: This study aims at observing placental pathologies in COVID-19 infected women, and analyzing its impact on pregnancy outcome. METHOD: This is a descriptive-analytical study done at a tertiary centre of Northern India. All COVID-19 positive pregnant women with gestational age ≥20 weeks, with placental histopathological reporting, were included in this study. A total of 173 COVID-19 pregnant women were included in the study. RESULTS: Placental abnormalities were noticed in 49·16% of total 179 placentae examined. Maternal vascular malperfusion (27·93%) was the most observed placental pathology followed by villous fibrin deposits (22·90%), fetal vasculopathy (16·75%), and acute inflammation (6·70%). Stillbirths were 22 and NICU admissions were seen in 50 neonates. Abnormal placental abnormalities led to higher stillbirths (p value 0·011) and lower Apgar scores at 1 and 5 min (p-value 0·028; p-value 0·002, respectively). Intervillous fibrin deposits had higher risk associated with lower Apgar score at 1 and 5 min [RR 2·05 (95% CI 1·21-3·48, p-value 0·010) and RR 5·52 (95% CI 2·58-11·81, p-value <0·001), respectively]. RP clot/hemorrhage was also associated with lower Apgar score at 1 and 5 min [RR 2·61 (95% CI 1·52-4·49, p-value 0·002) and RR 3.54 (95% CI 1·66-7·55, p-value 0·001), respectively]. DISCUSSION: Placental abnormalities in COVID-19 infection were associated with significant higher incidence of unexplained stillbirths, and lower Apgar scores. Although, this is the largest descriptive-analytical study done so far, comparative studies are required to draw a clear conclusion regarding the impact of COVID-19 infection on human placenta and its effect on pregnancy outcomes.

Hemangioma of the umbilical cord : a case report on a rare entity. (preprint)

Several hundred cases of placental hemangiomas have been reported in the literature. However, the umbilical cord is extremely uncommon as a site of occurence.We report the first case of hemangioma of the umbilical cord synchronous to maternal infection with covid-19.We aim to study the clinicopathological characteristics of this singular entity.

Blood biomarkers representing maternal-fetal interface tissues used to predict early-and late-onset preeclampsia but not COVID-19 infection (preprint)

Background: A well-known blood biomarker (soluble fms-like tyrosinase-1 [sFLT-1]) for preeclampsia, i.e., a pregnancy disorder, was found to predict severe COVID-19, including in males. True biomarker may be masked by more-abrupt changes related to endothelial instead of placental dysfunction. This study aimed to identify blood biomarkers that represent maternal-fetal interface tissues for predicting preeclampsia but not COVID-19 infection. Methods: The surrogate transcriptome of the tissues was determined by that in maternal blood, utilizing four datasets (n=1,354) which were collected before the COVID-19 pandemic. Applying machine learning, a preeclampsia prediction model was chosen between those using blood transcriptome (differentially expressed genes [DEGs]) and the blood-derived surrogate for the tissues. We selected the most predictive model by the area under receiver operating characteristic (AUROC) using a dataset for developing the model, and well-replicated in datasets either with or without intervention. To identify eligible blood biomarkers that predicted any-onset preeclampsia from the datasets but did not predict positives in the COVID-19 dataset (n=47), we compared several methods of predictor discovery: (1) the best prediction model; (2) gene sets by standard pipelines; and (3) a validated gene set for predicting any-onset preeclampsia during the pandemic (n=404). We chose the most predictive biomarkers from the best method with the significantly largest number of discoveries by a permutation test. The biological relevance was justified by exploring and reanalyzing low- and high-level, multi-omics information. Results: A prediction model using the surrogates developed for predicting any-onset preeclampsia (AUROC of 0.85, 95% confidence interval [CI] 0.77 to 0.93) was the only that was well-replicated in an independent dataset with no intervention. No model was well-replicated in datasets with a vitamin D intervention. None of the blood biomarkers with high weights in the best model overlapped with blood DEGs. Blood biomarkers were transcripts of integrin-5 (ITGA5), interferon regulatory factor-6 (IRF6), and P2X purinoreceptor-7 (P2RX7) from the prediction model, which was the only method that significantly discovered the eligible blood biomarkers (n=3/100 combinations, 3.0%; P=.036). Most of the predicted events (73.70%) among any-onset preeclampsia were cluster A as defined by ITGA5 (Z-score [≥]1.1), but were only a minority (6.34%) among positives in the COVID-19 dataset. The remaining were the predicted events (26.30%) among any-onset preeclampsia or those among COVID-19 infection (93.66%) if IRF6 Z-score was [≥]-0.73 (clusters B and C), in which none was the predicted events among either late-onset preeclampsia (LOPE) or COVID-19 infection if P2RX7 Z-score was <0.13 (cluster B). Greater proportion of predicted events among LOPE were cluster A (82.85% vs. 70.53%) compared to early-onset preeclampsia (EOPE). The biological relevance by multi-omics information explained the biomarker mechanism, polymicrobial infection in any-onset preeclampsia by ITGA5, viral co-infection in EOPE by ITGA5-IRF6, a shared prediction with COVID-19 infection by ITGA5-IRF6-P2RX7, and non-replicability in datasets with a vitamin D intervention by ITGA5. Conclusions: In a model that predicts preeclampsia but not COVID-19 infection, the important predictors were maternal-blood genes that were not extremely expressed, including the proposed blood biomarkers. The predictive performance and biological relevance should be validated in future experiments.

Regulation of Proinflammatory Molecules and Tissue Factor by SARS-CoV-2 Spike Protein in Human Placental Cells: Implications for SARS-CoV-2 Pathogenesis in Pregnant Women.

SARS-CoV-2 infects cells via binding to ACE2 and TMPRSS2, which allows the virus to fuse with host cells. The viral RNA is detected in the placenta of SARS-CoV-2-infected pregnant women and infection is associated with adverse pregnancy complications. Therefore, we hypothesize that SARS-CoV-2 infection of placental cells induces pro-inflammatory cytokine release to contribute to placental dysfunction and impaired pregnancy outcomes. First, expression of ACE2 and TMPRSS2 was measured by qPCR in human primary cultured term cytotrophoblasts (CTBs), syncytiotrophoblast (STBs), term and first trimester decidual cells (TDCs and FTDCs, respectively), endometrial stromal cells (HESCs) as well as trophoblast cell lines HTR8, JEG3, placental microvascular endothelial cells (PMVECs) and endometrial endothelial cells (HEECs). Later, cultured HTR8, JEG3, PMVECs and HEECs were treated with 10, 100, 1000 ng/ml of recombinant (rh-) SARS-CoV-2 S-protein ± 10 ng/ml rh-IFNγ. Pro-inflammatory cytokines IL-1ß, 6 and 8, chemokines CCL2, CCL5, CXCL9 and CXCL10 as well as tissue factor (F3), the primary initiator of the extrinsic coagulation cascade, were measured by qPCR as well as secreted IL-6 and IL-8 levels were measured by ELISA. Immunohistochemical staining for SARS-CoV-2 spike protein was performed in placental specimens from SARS-CoV-2-positive and normal pregnancies. ACE2 levels were significantly higher in CTBs and STBs vs. TDCs, FTDCs and HESCs, while TMPRSS2 levels were not detected in TDCs, FTDCs and HESCs. HTR8 and JEG3 express ACE2 and TMPRSS2, while PMVECs and HEECs express only ACE2, but not TMPRSS2. rh-S-protein increased proinflammatory cytokines and chemokines levels in both trophoblast and endothelial cells, whereas rh-S-protein only elevated F3 levels in endothelial cells. rh-IFNγ ± rh-S-protein augments expression of cytokines and chemokines in trophoblast and endothelial cells. Elevated F3 expression by rh-IFNγ ± S-protein was observed only in PMVECs. In placental specimens from SARS-CoV-2-infected mothers, endothelial cells displayed higher immunoreactivity against spike protein. These findings indicated that SARS-CoV-2 infection in placental cells: 1) induces pro-inflammatory cytokine and chemokine release, which may contribute to the cytokine storm observed in severely infected pregnant women and related placental dysfunction; and 2) elevates F3 expression that may trigger systemic or placental thrombosis.

Laminar Necrosis and Hypoxic Damage of the Placenta: A Case-Control Study.

The aim of this study is to verify the role of laminar necrosis (LN) in the diagnosis of hypoxic damage of the placenta. This is a retrospective case-control study in which 50 cases with laminar necrosis were compared with 100 gestational age-matched controls without laminar necrosis in a 1:2 ratio. The parameters analyzed were: the presence of other placental lesions, obstetric characteristics and neonatal outcome. For each of the 50 cases, the area affected by the lesion was detected, and the lesions were classified into three groups based on the morphology and time of onset of the lesion in order to understand whether these characteristics of the lesion had a clinical-pathology. The results showed that including the search for LN among placental lesions generally examined is useful to guide the pathologist in the diagnosis of placental dysfunction of hypoxic origin.

Bizarre Chorionic-type Trophoblast in Second-trimester and Third-trimester Placentas: Clinicopathologic Characterization of a Placental Pseudoneoplastic Lesion.

Bizarre (atypical/symplastic) cells have been described in various gynecologic normal tissues and benign neoplasms. This type of bizarre cytologic change is usually an incidental finding and is regarded as a benign process. We describe 17 cases of bizarre chorionic-type trophoblast in second-trimester and third-trimester placentas that created concern for an underlying/undersampled or incipient intraplacental trophoblastic neoplasm, predominantly found in intervillous trophoblastic islands (11/17), placental septae (6/17), chorionic plate (1/17), and/or the chorion layer of fetal membranes (2/17). The bizarre trophoblastic cells exhibited sheet-like or nested architecture, had a multifocal/patchy distribution, and/or were present as individual cells within hyaline stroma; they were characterized by large nuclei with smudgy chromatin and occasional intranuclear pseudoinclusions. The degree of atypia was classified as mild (0/17), moderate (3/17), or severe (14/17). Mitotic figures and necrosis were not identified. A dual immunohistochemical stain for trophoblast (hydroxyl-delta-5-steroid dehydrogenase) and a proliferation marker (Ki-67), performed in 15 cases, demonstrated 0% to very low proliferative activity within the bizarre trophoblast (0% to 2% [10/15], 3% to 8% [5/15]). Immunohistochemical stains for fumarate hydratase showed intact/retained expression in the bizarre cells in 7 of 7 cases. Clinical follow-up ranged from 1 to 45 months, and all patients were alive and well without subsequent evidence of a gestational trophoblastic or other neoplasms. We conclude that bizarre chorionic-type trophoblast in second-trimester or third-trimester placentas have the potential to mimic an intraplacental trophoblastic neoplasm but are likely a benign degenerative change. This study expands the spectrum of bizarre cells that occur in the gynecologic tract.

Could SARS-CoV-2 Infection Change Fetal Cardiac Output? (preprint)

Aim: We aimed to examine fetal cardiac output (CO) in patients who recovered from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Materials: This prospective study included 48 pregnant women recovered from SARS-CoV-2 infection and 50 control cases. SARS-CoV-2 infection was diagnosed by polymerase chain reaction (PCR) test in patients. Fetal echocardiographic evaluations were performed at 24-37 weeks of gestation in pregnant women who recovered from the infection and control group. Results: The median value of ultrasound evaluation was 34 (2.6) weeks of gestation in the recovery from the SARS-CoV-2 infection (RSI) group, and 32 (7.6) weeks in the control group (p=0.565). Left cardiac output (LCO) z score was significantly lower in the RSI group than the control group (p=0,041). LCO and combine cardiac output (CCO) z score were significantly lower in the severe disease group than mild, moderate disease groups, and controls (p=0,019 and p=0,013). CCO (mL/min/kg) was decreased in the severe disease group when compared with control and mild disease groups (p=0,044). Fetal distress, preterm delivery rate, and neonatal intensive care unit (NICU) admission were found to be higher in the severe disease group compared to the control group (p=0,010, p=0,009, and p<0,001 respectively). Conclusion: In the present study, fetal cardiac output in pregnant women with recovery from SARS-CoV-2 infection was found significantly decreased, especially in whom had severe diseases. Placental dysfunction and inflammatory cytokines might cause fetal cardiac changes. Further studies could be clarified on the impact of SARS-CoV-2 infection on fetal cardiac function.

Symptomatic versus asymptomatic COVID-19: does it impact placental vasculopathy?

This study sought to assess the impact of COVID-19 on placental vasculature in the context of maternal symptomatology - comparing asymptomatic to symptomatic pregnant patients - and disease severity - comparing pregnant patients with mild, moderate, severe, and critical COVID-19 infection. PCR-confirmed COVID-19 positive pregnant patients in a single health system who delivered between 3/2020-5/2021 included. All patients had positive COVID test and delivered during the study period. Primary outcome was incidence of any vascular malperfusion on placental pathology. Secondary outcomes were FVM and MVM on placental pathology. Placental pathology compared between symptomatic (sCOVID) and asymptomatic (aCOVID) patients. Secondary analysis of symptomatic patients, comparing placental pathology between mild disease(mCOVID) and worse disease(moderate, severe, or critical-defined by 2020 NIH guidelines) (dCOVID), also performed. Of 112 patients, 53 (47%) had symptoms. Twenty-seven (24.1%) patients had evidence of vascular malperfusion; 26 (23.2%) had MVM. When comparing aCOVID and sCOVID patients, no difference in rate of vascular malperfusion identified, nor any differences in rates of FVM or MVM. Among sCOVID patients (n = 53), 39 (74%) had mCOVID and 14 (26%) had dCOVID (moderate n = 4, severe n = 9, critical n = 1). Patients with dCOVID had earlier median delivery GA (37.4wks vs 39.2wks, p = .03). No difference in latency from diagnosis to delivery seen between mCOVID and dCOVID groups (4.4 vs 3.0wks, p = .96). Twelve (30.8%) patients had vascular malperfusion on pathology, all had mCOVID (p = .02). Eleven (28.2%) mCOVID patients had MVM; no dCOVID patients had evidence of vascular malperfusion (p = .03). No difference in FVM was found between cohorts. Symptomatic COVID-19 infection did not impact placental vasculature differently than asymptomatic infection, even when stratifying by trimester of infection. Among pregnant patients with symptomatic COVID-19, mild disease was associated with placental vascular changes on the maternal side while severe disease was not. Further studies are needed to understand the implications of these findings.

Intrauterine Fetal Demise After Uncomplicated COVID-19: What Can We Learn from the Case?

BACKGROUND: SARS-CoV-2 infection in pregnant women can lead to placental damage and transplacental infection transfer, and intrauterine fetal demise is an unpredictable event. CASE STUDY: A 32-year-old patient in her 38th week of pregnancy reported loss of fetal movements. She overcame mild COVID-19 with positive PCR test 22 days before. A histology of the placenta showed deposition of intervillous fibrinoid, lympho-histiocytic infiltration, scant neutrophils, clumping of villi, and extant infarctions. Immunohistochemistry identified focal SARS-CoV-2 nucleocapsid and spike protein in the syncytiotrophoblast and isolated in situ hybridization of the virus' RNA. Low ACE2 and TMPRSS2 contrasted with strong basigin/CD147 and PDL-1 positivity in the trophoblast. An autopsy of the fetus showed no morphological abnormalities except for lung interstitial infiltrate, with prevalent CD8-positive T-lymphocytes and B-lymphocytes. Immunohistochemistry and in situ hybridization proved the presence of countless dispersed SARS-CoV-2-infected epithelial and endothelial cells in the lung tissue. The potential virus-receptor protein ACE2, TMPRSS2, and CD147 expression was too low to be detected. CONCLUSION: Over three weeks' persistence of trophoblast viral infection lead to extensive intervillous fibrinoid depositions and placental infarctions. High CD147 expression might serve as the dominant receptor for the virus, and PDL-1 could limit maternal immunity in placental tissue virus clearance. The presented case indicates that the SARS-CoV-2 infection-induced changes in the placenta lead to ischemia and consecutive demise of the fetus. The infection of the fetus was without significant impact on its death. This rare complication of pregnancy can appear independently to the severity of COVID-19's clinical course in the pregnant mother.

Association of antepartum and intrapartum SARS-CoV-2 infection on pregnancy outcomes in South African women, two observational studies (preprint)

Objective: Evaluate the impact of the timing of SARS-CoV-2 infection on pregnancy outcomes in a low-middle income setting. Design: two parallel, observational studies. Setting and population: pregnant women or women presenting for labour, enrolled between April-September 2020, in South Africa. Methods: i) longitudinal follow-up study of symptomatic or asymptomatic pregnant women investigated for SARS-CoV-2 infection antenatally, ii) cross-sectional study of SARS-CoV-2 infection at time of labour. SARS-CoV-2 infection was investigated by nucleic acid amplification test (NAAT). Main Outcome Measures: association of SARS-CoV-2 infection on nasal swab and birth outcomes. Results: Antenatally, 793 women were tested for SARS-CoV-2. Overall SARS-CoV-2 infection was confirmed in 138 women, including 119/275 with symptomatic illness (COVID-19) and 19/518 asymptomatic women; 493 women were asymptomatic and SARS-CoV-2 non-reactive. Women with COVID-19 were 1.66-times (95%CI: 1.02, 1.71) more likely to have a low-birthweight newborn (30%) compared to asymptomatic women without SARS-CoV-2 (21%). Overall, 3117 women were tested for SARS-CoV-2 infection at delivery, including 1560 healthy women with an uncomplicated term delivery. Adverse birth outcomes or pregnancy-related complications were not associated with infection at delivery. Among women with SARS-CoV-2 infection at delivery, NAAT was reactive on 6/98 of maternal blood samples, 8/93 of cord-blood, 14/54 of placentas and 3/22 of nasopharyngeal swabs from newborns collected within 72-hours of birth. Conclusions: Antenatal, but not intrapartum, SARS-CoV-2 infection was associated with low-birthweight delivery. Maternal infection at the time of labour was associated with in utero foetal and placental infection, and possible vertical and/or horizontal viral transfer to the newborn.

Placental deficiency during maternal SARS-CoV-2 infection.

INTRODUCTION: Maternal anti-SARS-CoV-2 Spike antibodies can cross the placenta during pregnancy, and neonates born to infected mothers have acquired antibodies at birth. Few studies reported data on the histopathological changes of the placenta during infection and placental infection. SARS-CoV-2 infection may cause impaired development of the placenta, thus predisposing maternal and fetal unfavorable outcomes. The prospective study aims to evaluate the risk of vertical transmission of SARS-CoV-2 and placental passage of anti-Spike antibodies as well as the impact of clinical severity on placental structures. METHODS: This is a prospective cohort study on 30 pregnant women infected by SARS-CoV-2 with their neonates. The demographic features and pregnancy outcomes were collected. Gross and microscopic examinations of the placentas were done. Maternal and umbilical cord sera were obtained at the time of delivery. Nasopharyngeal swabs were collected from neonates immediately after birth. RESULTS: The concentrations of total anti-SARS-CoV-2 Spike antibodies were higher in pregnant women with moderate to severe/critical disease. The maternal total anti-SARS-CoV-2 Spike levels were correlated with those of neonatal levels. The rate of placental abnormalities is high in the mothers with severe disease, and those with positive anti-SARS-CoV-2 IgM. All neonates had negative nasopharyngeal swabs for SARS- CoV-2 infections and all placentas were negative in immunohistochemical staining for Spike protein. DISCUSSION: The maternally derived anti-SARS-CoV-2 Spike antibody can transmit to neonates born to infected mothers regardless of gestational age. Our results indicated that the disease severity is associated with ischemic placental pathology which may result in adverse pregnancy outcomes.

The Effect of COVID-19 Infection During Pregnancy; Evaluating Neonatal Outcomes and the Impact of the B.1.1.7. Variant.

BACKGROUND: Coronavirus disease 2019 (COVID-19) infection during pregnancy has been associated with adverse perinatal outcomes. We aim to evaluate the neonatal outcomes including the incidence of preterm birth, admission to the neonatal unit and incidence of congenital anomalies in this cohort. We will also describe these outcomes in the context of the B.1.1.7. variant outbreak, the dominant variant in Ireland since January 2021, which has had a greater impact on pregnant patients. METHODS: This was a retrospective study of liveborn infants, delivered between 1st March 2020 and 1st March 2021, to women with a severe acute respiratory syndrome coronavirus 2 diagnosis during pregnancy, in a tertiary maternity hospital (8,500 deliveries/year). Clinical data were collected, and analyses were performed to evaluate the impact of maternal symptom status, time from diagnosis to delivery and the B.1.1.7. variant on neonatal outcome. RESULTS: In total 133 infants (1.6%) were born to women with severe acute respiratory syndrome coronavirus 2 identified during pregnancy. The median birth weight was 3.45 kg and gestational age at birth was 39.3 weeks. 14 infants (10.5%) were preterm. 22 infants (16.5%) required admission to the neonatal unit and 7 (5.3%) were small for gestational age. There was no difference in growth, preterm birth or neonatal unit admission based on maternal symptom status or infection after the outbreak of B.1.1.7. as the dominant strain. CONCLUSIONS: Following a COVID-19 infection in pregnancy, there was no increase in the incidence of preterm birth or neonatal intensive care unit admission compared with 5-year hospital data. Maternal symptom status did not influence neonatal outcomes. Further studies to evaluate the impact of COVID-19 in early pregnancy, the variants of concern, particularly the emerging Delta variant and COVID-19 placentitis are required.

A standardized definition of placental infection by SARS-CoV-2, a consensus statement from the National Institutes of Health/Eunice Kennedy Shriver National Institute of Child Health and Human Development SARS-CoV-2 Placental Infection Workshop.

Pregnant individuals infected with SARS-CoV-2 have higher rates of intensive care unit admission, oxygen requirement, need for mechanical ventilation, and death than nonpregnant individuals. Increased COVID-19 disease severity may be associated with an increased risk of viremia and placental infection. Maternal SARS-CoV-2 infection is also associated with pregnancy complications such as preeclampsia and preterm birth, which can be either placentally mediated or reflected in the placenta. Maternal viremia followed by placental infection may lead to maternal-fetal transmission (vertical), which affects 1% to 3% of exposed newborns. However, there is no agreed-upon or standard definition of placental infection. The National Institutes of Health/Eunice Kennedy Shriver National Institute of Child Health and Human Development convened a group of experts to propose a working definition of placental infection to inform ongoing studies of SARS-CoV-2 during pregnancy. Experts recommended that placental infection be defined using techniques that allow virus detection and localization in placental tissue by one or more of the following methods: in situ hybridization with antisense probe (detects replication) or a sense probe (detects viral messenger RNA) or immunohistochemistry to detect viral nucleocapsid or spike proteins. If the abovementioned methods are not possible, reverse transcription polymerase chain reaction detection or quantification of viral RNA in placental homogenates, or electron microscopy are alternative approaches. A graded classification for the likelihood of placental infection as definitive, probable, possible, and unlikely was proposed. Manuscripts reporting placental infection should describe the sampling method (location and number of samples collected), method of preservation of tissue, and detection technique. Recommendations were made for the handling of the placenta, examination, and sampling and the use of validated reagents and sample protocols (included as appendices).

Pandemic stress and SARS-CoV-2 infection are associated with pathological changes at the maternal-fetal interface.

INTRODUCTION: The reported effects of SARS-CoV-2 on pregnancy outcomes are conflicting; studies frequently overlook the placenta, which is critical for the health of the mother and infant(s). This study aimed to determine the effect of pandemic stress ± SARS CoV-2 infection on placental histopathology. METHODS: Women were recruited in Canada (n = 69); France (n = 21) or in the UK (n = 25), between March and October 2020. Historic controls (N = 20) were also included. Placenta and fetal membrane samples were collected rapidly after delivery and were fixed and stained for histopathological analysis. Maternal demographical data and obstetric outcomes were recorded. RESULTS: Over 80% of the placentas from SARS-CoV-2+ pregnancies had histopathological abnormalities: predominantly structural (71-86%) or inflammatory (9-22%), depending on geographical location. Excessive fibrin was seen in all sites, whereas deciduitis (Canada), calcifications (UK), agglutinations and chorangiosis (France) predominated in different locations. The frequency of abnormalities was significantly higher than in SARS-CoV-2 negative women (50%, p < 0.05). Demographic and obstetric data were similar in the SARS-CoV-2+ women across all sites - characterised by predominantly Black/Middle Eastern women, and women with elevated body mass index. DISCUSSION: Overall, the frequency of placental abnormalities is increased in SARS-CoV-2+ women, but the incidence of placental abnormalities is also higher in SARS-CoV-2- women that gave birth during the pandemic, which highlights the importance of appropriate control groups to ascertain the roles of pandemic stress and SARS-CoV-2 infection on the placenta and pregnancy outcomes.

Third trimester stillbirth during the first wave of the SARS-CoV-2 pandemic: Similar rates with increase in placental vasculopathic pathology.

Whether early SARS-CoV-2 definitively increases the risk of stillbirth is unknown, though studies have suggested possible trends of stillbirth increase during the pandemic. This study of third trimester stillbirth does not identify an increase in rates during the first wave of the pandemic period, however investigation of the placental pathology demonstrates trends towards more vascular placental abnormalities.

Unique Severe COVID-19 Placental Signature Independent of Severity of Clinical Maternal Symptoms.

BACKGROUND: Although the risk for transplacental transmission of SARS-CoV-2 is rare, placental infections with adverse functional consequences have been reported. This study aims to analyse histological placental findings in pregnancies complicated by SARS-CoV-2 infection and investigate its correlation with clinical symptoms and perinatal outcomes. We want to determine which pregnancies are at-risk to prevent adverse pregnancy outcomes related to COVID-19 in the future. METHODS: A prospective, longitudinal, multicentre, cohort study. All pregnant women presenting between April 2020 and March 2021 with a nasopharyngeal RT-PCR-confirmed SARS-CoV-2 infection were included. Around delivery, maternal, foetal and placental PCR samples were collected. Placental pathology was correlated with clinical maternal characteristics of COVID-19. RESULTS: Thirty-six patients were included, 33 singleton pregnancies (n = 33, 92%) and three twin pregnancies (n = 3, 8%). Twenty-four (62%) placentas showed at least one abnormality. Four placentas (4/39, 10%) showed placental staining positive for the presence of SARS-CoV-2 accompanied by a unique combination of diffuse, severe inflammatory placental changes with massive perivillous fibrin depositions, necrosis of syncytiotrophoblast, diffuse chronic intervillositis, and a specific, unprecedented CD20+ B-cell infiltration. This SARS-CoV-2 placental signature seems to correlate with foetal distress (75% vs. 15.6%, p = 0.007) but not with the severity of maternal COVID-19 disease. CONCLUSION: We describe a unique placental signature in pregnant patients with COVID-19, which has not been reported in a historical cohort. We show that the foetal environment can be seriously compromised by disruption of placental function due to local, devastating SARS-CoV-2 infection. Maternal clinical symptoms did not predict the severity of the SARS-CoV-2-related placental signature, resulting in a lack of adequate identification of maternal criteria for pregnancies at risk. Close foetal monitoring and pregnancy termination in case of foetal distress can prevent adverse pregnancy outcomes due to COVID-19 related placental disease.