Placental pathology of the third trimester pregnant women from COVID-19

The effect of COVID-19 on placental functioning in South African pregnancies: investigation of kisspeptin expression and vascular and inflammatory alterations

The coronavirus disease 2019 (COVID-19) pandemic has passed; however, its long-term effects are yet to be determined. Pregnant women and their neonates faced a higher risk for complications during this pandemic as COVID-19 was reported to result in oxidative and inflammatory stress and the cytokine storm, which would impact pregnancy, namely the trophoblast invasion and placental development and functioning. Therefore, this study aims to determine the effect of COVID-19 on the placental functioning in South African pregnancies through the analysis of kisspeptin and placental morphology. Immunohistochemical analyses of placental samples were performed to detect the expression of kisspeptin. Histopathological analysis was conducted to identify vascular and inflammatory alterations. This study demonstrated that COVID-19 results in a significantly increased expression of placental kisspeptin in both the central (p = 0.001) and peripheral (p < 0.0001) regions as compared with the placentae from control pregnancies. Upon further analysis, the placentae from COVID-19 pregnancies also presented with severe inflammation and maternal and fetal vascular malperfusion compared with the control placentae. A significantly increased expression of placental kisspeptin was observed in COVID-19 positive pregnancies, implying impaired placental functioning. This was further supported by vascular and inflammatory alterations observed in COVID-19-positive placentae, which may suggest that trophoblast invasion was compromised. To date, there still exists small clusters of COVID-19 outbreaks, and our findings highlight the importance of the future surveillance of these mothers and neonates in COVID-19 pregnancies in South Africa, as neonates from other countries have presented with abnormalities.

Controversies in chronic histiocytic intervillositis

Understanding the"paradox" of pregnancy remains a challenging field of investigation especially when immunological dysregulation is suspected in pathological pregnancies. Chronic histiocytic intervillositis (CHI) is an example of a rare placental inflammatory disease that can occur during any trimester of pregnancy. The pathogenesis of CHI involves an abnormal immune response characterized by an inflammatory infiltrate of maternal CD68+ mononuclear immune cells in the intervillous space. CHI may be associated with villous and intervillous fibrinoid deposits. The precise immunological mechanism is not yet fully understood; it probably relies on an allo-immune of graft rejection rather than an auto-immune mechanism, although it has been described in several autoimmune diseases. CHI has also been described in COVID19 infected pregnant women. The recurrence rate is high and complications are severe: CHI is strongly associated with fetal growth restriction, miscarriage and stillbirth. The management of these patients remains an issue lacking of -standardized guidelines. The aim of this narrative review is to focus on the knowledge, pathogenesis, diagnosis and treatment of CHI over the last 5 years.

Enhancing the Diagnostic Accuracy of Placental Pathology by Using the Amsterdam Consensus Criteria

Background and objective Standardizing placental pathology diagnoses is crucial for improving diagnostic accuracy and clinical communication. The Amsterdam Consensus Criteria were developed to address inconsistencies in diagnosing significant placental pathologies. This study aimed to assess the application and effectiveness of the Amsterdam Consensus Criteria in diagnosing placental pathologies, with a focus on improving the reliability and precision of placental pathology reports. Methods A retrospective review of 100 consecutively archived placental pathology samples was performed at a tertiary care hospital. These samples, gathered from January through December 2021, were reassessed according to the Amsterdam criteria. The revised diagnoses were then compared with the original descriptive diagnoses. Results Significant changes were noted in all principal diagnoses, including maternal vascular malperfusion (MVM), fetal vascular malperfusion (FVM), chronic villitis of unknown etiology (VUE), and acute chorioamnionitis (ACA). This evaluation led to a recategorization of several cases. Frequently, parenchymal infarcts were reported without adequate information to ascertain their association with MVM. Additionally, there was a noticeable lack of understanding of FVM and VUE among pathologists. ACA was the condition most consistently documented. However, detailed grading and staging were often not included. Conclusions Our findings emphasize the need to use standardized diagnostic criteria, such as the Amsterdam criteria, to enhance diagnostic accuracy and facilitate communication between pathologists and clinicians. This will ultimately lead to improved patient care outcomes. It also underlines the necessity of continuous education and calibration for pathologists to mitigate interobserver variability. There is a demand to modify these criteria to ensure universal applicability and relevance in various clinical settings.

Maternal COVID-19 exposure and placental characteristics

INTRODUCTION

The impact of COVID-19 on the placenta is poorly described, particularly among minority women.

MATERIALS AND METHODS

This is a retrospective case-control study. Micro- and macroscopic placental pathologic findings were compared for 15 COVID-19 positive and 36 negative mothers. Cases and controls were frequency matched on gestational age, race, maternal comorbidities, and delivery type. Data from the electronic medical record were supplemented with independent review of microscopic slides.

RESULTS

Placentas from cases and controls were similar except the median distance from the site of the cord insertion to the nearest disk margin was statistically significantly shorter among placentas from COVID-19 positive cases (3.5 versus 6.0 cm, p = 0.006). Case status was not associated with an increased risk of placental pathologies.

CONCLUSION

There are few pathologic differences between placentas of COVID-19 positive and negative mothers. Additional studies are needed to investigate the role of timing of infection.

Effects of SARS-Cov-2 mRNA vaccine on placental histopathology: Comparison of a population of uncomplicated COVID-19 positive pregnant women

1.

INTRODUCTION

This study investigates the impact of SARS-CoV-2 infection on placental histopathology in pregnant women, comparing outcomes between vaccinated and non-vaccinated individuals. Despite known adverse pregnancy outcomes linked to SARS-CoV-2 infection, the specific effects on the placenta remain unclear. Although vaccination has demonstrated a substantial reduction in infection severity, its impact on placental health requires more insight. 2.

METHODS

Between March 2021 and July 2022, 387 COVID-19-positive women were admitted for delivery. Of these, 98 with non-severe symptoms were analyzed: 35 vaccinated during pregnancy, and 63 non-vaccinated. Two independent pathologists evaluated all placental specimens. 3.

RESULTS

The only differing obstetrical characteristic between groups was the mode of delivery (p 0.047), lacking clinical implications. Over 85% of placentas exhibited microscopic abnormalities, predominantly maternal vascular supply disorders (vaccinated 89.1%; unvaccinated 85.5%). Comparing vaccinated and unvaccinated groups revealed statistically significant differences, notably in increased focal perivillous fibrin deposits (IFPFD) [17.1% vs. 33.3% (p 0.04)] and avascular fibrotic villi (AFV) [0% vs. 11.1% (p 0.04)]. Binomial logistic regression confirmed the vaccine's protective role against IFPFD (aOR 0.36; 95%CI 013-0.99) and AVF (aOR 0.06, 95% CI 0.003-0.98). A sub-analysis in vaccinated women showed a positive correlation between the timing of the first dose and IFPFD presence (p 0.018). 4.

DISCUSSION

The lower incidence of maternal and fetal vascular malperfusion placental features in vaccinated women, coupled with the timing correlation, supports the vaccine's protective effect on placental tissue in COVID-19-infected pregnant patients. Notably, no side effects were reported post-vaccination, emphasizing the vaccine's safety and advocating for its secure administration in pregnant populations.

Histological and immunohistochemical features of the placenta associated with COVID-19: a systematic review and meta-analysis

OBJECTIVE

Aim: To make a systematic review and meta-analysis of published data on the study of histological and immunohistochemical features of the placenta in women who had acute coronavirus infection associated with SARS-CoV-2 ("Covid" placentas) during pregnancy.

PATIENTS AND METHODS

Materials and Methods: The search for literature data is based on the PRISMA methodology); the MEDLINE database (PubMed®) was searched using Medical Subject Headings terms from January 2020 to July 2023. The project was registered in the Open Sience Frame (Project Identifier: DOI 10.17605/OSF.IO/GDR3S, Registration DOI: https://doi.org/10.17605/OSF.IO/H2KPU). Preference was given to studies in which the description of placentas met the requirements of the Amsterdam Placental Workshop Group Consensus Statement.

RESULTS

Results: A total of 31 studies were included; the number of participants whose morphological and histological description of the placentas could be subjected to meta-analysis was 2401, respectively, in the group with a "Covid" history and 1910 - conditionally healthy pregnant women. Pathological changes in the placental complex were not detected in 42±19.62% of pregnant women with a history of Covid. Immunohistochemical examination of placentas preferably focuses on the detection of SARS-CoV-2 spike protein or ACE2. According to currently available studies, in the placentas of women who have had COVID-19 during pregnancy, there are no pathognomic histological patterns specific to this infection and direct damage to the placenta is rarely observed. Histological patterns in "covid" placentas are isolated, most often a combination of lesions in both the maternal and fetal malperfusion.

CONCLUSION

Conclusions: According to currently available studies, in the placentas of women who have had COVID-19 during pregnancy, there are no pathognomic histological patterns specific to this infection and direct damage to the placenta is rarely observed. The probability of infection of the intrauterine fetus by the transplacental hematogenous route is the lowest compared to other routes, which, in our opinion, is a possible explanation for the high frequency of MVM without subsequent infection of the fetus.

Clinical Features of SARS-CoV-2 Infection During Pregnancy and Associated Placental Pathologies

SUMMARY

We reviewed the clinicopathologic findings of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-exposed placentas at our institution. We identified patients diagnosed with SARS-CoV-2 during pregnancy (March-October 2020). Clinical data included gestational age at diagnosis and delivery and maternal symptoms. Hematoxylin and eosin slides were reviewed for maternal vascular malperfusion, fetal vascular malperfusion, chronic villitis, amniotic fluid infection, intervillous thrombi, fibrin deposition, and infarction. Immunohistochemistry (IHC) for coronavirus spike protein and RNA in situ hybridization (ISH) for SARS-CoV-2 was performed on a subset of blocks. A review of placentas from age-matched patients received March-October 2019 was conducted as a comparison cohort. A total of 151 patients were identified. Placentas in the 2 groups were similar in weight for gestational age and had similar rates of maternal vascular malperfusion, fetal vascular malperfusion, amniotic fluid infection, intervillous thrombi, fibrin deposition, and infarction. Chronic villitis was the only significantly different pathologic finding between cases and controls (29% of cases showed chronic villitis vs. 8% of controls, P <0.001). Overall, 146/151 (96.7%) cases were negative for IHC and 129/133 (97%) cases were negative for RNA ISH. There were 4 cases that stained positively for IHC/ISH, 2 of which showed massive perivillous fibrin deposition, inflammation, and decidual arteriopathy. Coronavirus disease 2019 (COVID-19)-positive patients were more likely to self-identify as Hispanic and more likely to have public health insurance. Our data suggests SARS-CoV-2 exposed placentas that stain positively for SARS-CoV-2 show abnormal fibrin deposition, inflammatory changes, and decidual arteriopathy. The group of patients with clinical COVID-19 are more likely to show chronic villitis. IHC and ISH evidence of viral infection is rare.

Placental pathology in SARS-CoV-2 infected pregnancies: A single-institution retrospective cohort analysis

BACKGROUND

Our objectives were to determine 1) the prevalence and description of placental pathologic lesions in pregnancies complicated by SARS-CoV-2 infection compared to healthy controls and 2) whether the prevalence and/ or pattern of placental pathologic lesions differed in the few neonates who tested positive for SARS-CoV-2 in the first 48 hours of life at a busy urban county hospital.

METHODS

This study included all pregnant mothers who tested positive for SARS-CoV-2 and delivered at our institution from March 2020 to June 2021, while control placentas were collected from term pregnancies without complications.

RESULTS

Approximately 90% (n = 380/425) of placentas from pregnancies complicated by SARS-CoV-2 infections had placental pathologic lesions, compared to 32% (n = 16/50) of controls. The predominant lesions were acute histologic chorioamnionitis with or without fetal response (n = 209/380, 55%), maternal vascular malperfusion (n = 180/380, 47%), and other inflammatory lesions (n = 148/380, 39%). Only 14 (2.5%) infants tested positive for SARS-CoV-2 within the first 48 hours of life. There were no significant differences in placental histopathology between infants who tested positive vs. those that were negative for SARS-CoV-2. Placental lesions in mothers who tested positive for SARS-CoV-2 during the first vs. second vs. third pregnancy trimesters, were significantly different in the incidence of inflammatory placental pathologic lesions (n = 9/19, 53% vs. n = 37/98, 49% vs. n = 102/439, 31%, respectively; p < 0.01).

CONCLUSION

A significant proportion of women with SARS-CoV-2 infection during pregnancy at a single county hospital have inflammatory and vascular placental lesions at birth, raising questions regarding their downstream effects and clinical consequences.

Mild/asymptomatic COVID-19 in unvaccinated pregnant mothers impairs neonatal immune responses

Maternal SARS-CoV-2 infection triggers placental inflammation and alters cord blood immune cell composition. However, most studies focus on outcomes of severe maternal infection. Therefore, we analyzed cord blood and chorionic villi from newborns of unvaccinated mothers who experienced mild/asymptomatic SARS-CoV-2 infection during pregnancy. We investigated immune cell rewiring using flow cytometry, single-cell RNA sequencing, and functional readouts using ex vivo stimulation with TLR agonists and pathogens. Maternal infection was associated with increased frequency of memory T and B cells and nonclassical monocytes in cord blood. Ex vivo T and B cell responses to stimulation were attenuated, suggesting a tolerogenic state. Maladaptive responses were also observed in cord blood monocytes, where antiviral responses were dampened but responses to bacterial TLRs were increased. Maternal infection was also associated with expansion and activation of placental Hofbauer cells, secreting elevated levels of myeloid cell-recruiting chemokines. Moreover, we reported increased activation of maternally derived monocytes/macrophages in the fetal placenta that were transcriptionally primed for antiviral responses. Our data indicate that even in the absence of vertical transmission or symptoms in the neonate, mild/asymptomatic maternal COVID-19 altered the transcriptional and functional state in fetal immune cells in circulation and in the placenta.

SARS-CoV-2 Infection during Pregnancy Followed by Thalamic Neonatal Stroke-Case Report

A neonatal stroke is a cerebrovascular process caused by interruption of cerebral blood flow that occurs with an incidence between 1 per 1600 and 1 per 2660 live births. Relative higher incidence in the neonatal period compared to later childhood is favored by the hypercoagulability state of the mother, mechanical stress during delivery, transient right to left intracardiac shunt, high hematocrit, blood viscosity, and risk of dehydration during the first few days of life. The exact cause of a neonatal stroke remains unclear in many cases. About 80% of neonatal strokes are due to arterial ischemic events involving the middle cerebral artery. Typical clinical manifestations in a neonatal stroke are usually seizures that appear immediately after birth or after several days of life, but many of the cases may remain asymptomatic. We present the case of a late preterm infant diagnosed with a thalamic stroke on the fifth day of life with no clinical signs except for repeated episodes of apnea. The anamnesis and clinical context, in this case, revealed a SARS-CoV-2 infection in late pregnancy and early bacterial neonatal sepsis. Early identification of a perinatal stroke and increasing awareness of physicians about this condition in the neonatal period have paramount importance to reduce developmental postischemic damage.

The effects of COVID-19 on placental morphology

The impact of the COVID-19 infection, caused by Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), during the pandemic has been considerably more severe in pregnant women than non-pregnant women. Therefore, a review detailing the morphological alterations and physiological changes associated with COVID-19 during pregnancy and the effect that these changes have on the feto-placental unit is of high priority. This knowledge is crucial for these mothers, their babies and clinicians to ensure a healthy life post-pandemic. Hence, we review the placental morphological changes due to COVID-19 to enhance the general understanding of how pregnant mothers, their placentas and unborn children may have been affected by this pandemic. Based on current literature, we deduced that COVID-19 pregnancies were oxygen deficient, which could further result in other pregnancy-related complications like preeclampsia and IUGR. Therefore, we present an up-to-date review of the COVID-19 pathophysiological implications on the placenta, covering the function of the placenta in COVID-19, the effects of this virus on the placenta, its functions and its link to other gestational complications. Furthermore, we highlight the possible effects of COVID-19 therapeutic interventions on pregnant mothers and their unborn children. Based on the literature, we strongly suggest that consistent surveillance for the mothers and infants from COVID-19 pregnancies be prioritised in the future. Though the pandemic is now in the past, its effects are long-term, necessitating the monitoring of clinical manifestations in the near future.

Mild/Asymptomatic Maternal SARS-CoV-2 Infection Leads to Immune Paralysis in Fetal Circulation and Immune Dysregulation in Fetal-Placental Tissues

Few studies have addressed the impact of maternal mild/asymptomatic SARS-CoV-2 infection on the developing neonatal immune system. In this study, we analyzed umbilical cord blood and placental chorionic villi from newborns of unvaccinated mothers with mild/asymptomatic SARSCoV-2 infection during pregnancy using flow cytometry, single-cell transcriptomics, and functional assays. Despite the lack of vertical transmission, levels of inflammatory mediators were altered in cord blood. Maternal infection was also associated with increased memory T, B cells, and non-classical monocytes as well as increased activation. However, ex vivo responses to stimulation were attenuated. Finally, within the placental villi, we report an expansion of fetal Hofbauer cells and infiltrating maternal macrophages and rewiring towards a heightened inflammatory state. In contrast to cord blood monocytes, placental myeloid cells were primed for heightened antiviral responses. Taken together, this study highlights dysregulated fetal immune cell responses in response to mild maternal SARS-CoV-2 infection during pregnancy.

Effect of severe acute respiratory syndrome coronavirus 2 infection during pregnancy in K18-hACE2 transgenic mice

OBJECTIVE

This study aimed to examine the influence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on pregnancy in cytokeratin-18 (K18)-hACE2 transgenic mice.

METHODS

To determine the expression of hACE2 mRNA in the female reproductive tract of K18-hACE2 mice, real-time polymerase chain reaction (RT-PCR) was performed using the ovary, oviduct, uterus, umbilical cord, and placenta. SARS-CoV-2 was inoculated intranasally (30 μL/mouse, 1×104 TCID50/mL) to plug-checked K18-hACE2 homozygous female mice at the pre-and post-implantation stages at 2.5 days post-coitum (dpc) and 15.5 dpc, respectively. The number of implantation sites was checked at 7.5 dpc, and the number of normally born pups was investigated at 20.5 dpc. Pregnancy outcomes, including implantation and childbirth, were confirmed by comparison with the non-infected group. Tissues of infected mice were collected at 7.5 dpc and 19.5 dpc to confirm the SARS-CoV-2 infection. The infection was identified by performing RT-PCR on the infected tissues and comparing them to the non-infected tissues.

RESULTS

hACE2 mRNA expression was confirmed in the female reproductive tract of the K18-hACE2 mice. Compared to the non-infected group, no significant difference in the number of implantation sites or normally born pups was found in the infected group. SARS-CoV-2 infection was detected in the lungs but not in the female reproductive system of infected K18-hACE2 mice.

CONCLUSION

In K18-hACE2 mice, intranasal infection with SARS-CoV-2 did not induce implantation failure, preterm labor, or miscarriage. Although the viral infection was not detected in the uterus, placenta, or fetus, the infection of the lungs could induce problems in the reproductive system. However, lung infections were not related to pregnancy outcomes.

Perinatal Cerebral Ischemic Lesion and SARS-CoV-2 Infection during Pregnancy: A Case Report and a Review of the Literature

Perinatal stroke is related to possible differences in predisposing factors and outcomes between acutely and retrospectively diagnosed cases. In most cases, there are different risk factors and infections that could play an important role. Thus far, different clinical manifestations have been reported in children presenting with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), ranging from asymptomatic status to severe disease sustained by an immune-mediated inflammatory response. SARS-CoV-2 has been associated with severe neurological diseases including seizures and encephalitis in both adults and children. However, there are still few reports regarding the possible relation between SARS-CoV-2 infection of mothers during pregnancy and the neurologic outcome of the newborns. We described the case of a newborn diagnosed with a perinatal stroke, born at 35 weeks of gestation from a mother presenting with SARS- CoV-2 infection during the last months of pregnancy. We also added a brief review of the literature with similar cases. Close monitoring and early intervention in young children born to infected mothers would be highly recommended for the potential neurodevelopmental risk.

SARS-CoV-2 Infection during Pregnancy and Histological Alterations in the Placenta

(1) Background: Despite the high number of cases of COVID-19 during pregnancy, SARS-CoV-2 congenital infection is rare. The role of the placenta as a barrier preventing the transmission of SARS-CoV-2 from the mother to the fetus is still being studied. This study aimed to evaluate the impact of SARS-CoV-2 infection on placental tissue. (2) Methods: This was a transversal monocentric observational study. In the study, we included pregnant women with COVID-19 who delivered at “Sfântul Pantelimon” Clinical Emergency Hospital between 1 April 2020 and 30 March 2022. Histological analyses, both macroscopic and microscopic, were performed for placentas that came from these cases. (3) Results: To date, a characteristic placental lesion has not been clearly demonstrated, but most findings include features of maternal and fetal vascular malperfusion, which probably reflect the reduction in placental blood flow due to low oxygen level from the hypoxic respiratory disease and underlying hypercoagulable state induced by the COVID-19 infection. (4) Conclusions: The histopathological aspects found in placentas that came from COVID-19-positive pregnant women are common for many other diseases, but when they are found together, they are highly suggestive for viral infectious involvement of the placenta.

Placental pathology in sudden intrauterine death (SIUD) in SARS-CoV-2-positive oligosymptomatic women

Background

Pregnant women are also susceptible to SARS-CoV-2. Although an infection of the placenta may be rare, pregnancy may occasionally be affected by intrauterine failure. The knowledge of placental morphology on sudden intrauterine demise is still limited.

Methods

Fetal and placental tissue of two cases of sudden intrauterine death in the second trimester were analysed morphologically and by immunohistochemistry. One case was evaluated by RT-PCR.

Results

Both mothers were tested positive for the Alpha variant of SARS-CoV-2 but were oligosymptomatic for COVID-19. Unexpected sudden intrauterine death (SIUD) occurred at 15 + 2 and 27 + 3 weeks of gestation. One fetus demonstrated an intrauterine growth restriction. No malformations nor inflammatory changes were observed in either fetus on autopsy. In contrast to the placentas, the fetal tissue was negative for SARS-CoV-2 on immunohistochemical and RT-PCR analyses. Macroscopically, the placentas showed an increased consistency with a white, reticular cutting surface covering about 95% of the whole placenta. Only very focal histiocytic chronic intervillositis was noted histologically. Massive perivillous fibrin deposits with extensive necroses of the villous trophoblast were present in more than 90% of the placental tissue. Immunohistochemical staining was strong and diffusely positive for SARS-CoV-2 in the villous trophoblast and rarely within the villous stromal cells. Placental SARS-CoV-2 infection was confirmed by RT-PCR.

Conclusion

Sudden intrauterine death may occur in mothers who are oligosymptomatic for COVID-19. Acute placental failure is responsible for SIUD, demonstrated by massive perivillous fibrin deposits and extensive necroses of the villous trophoblast with SARS-CoV-2-positivity based on immunohistochemical staining and RT-PCR. Detailed histopathological examination of placental and fetal tissue is mandatory to verify SARS-CoV-2 and to evaluate the pathogenesis and functionality of this disease.

Pathological involvement of placenta in COVID-19: a systematic review

The mammalian placenta, which is responsible for bonding between the mother and the fetus, is one of the first organs to develop. Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection has caused a great threat to public health and affected almost all the organs including the placenta. Owing to limited available data on vertical transmission and pathological changes in the placenta of SARS-CoV-2 positive patients, we aim to review and summarize histopathological and ultrastructural changes in the placental tissue following SARS-CoV-2 infection. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2009 guidelines were used for review writing. Multiple studies have reported significant pathological changes in the placental tissue of SARS-CoV-2 positive mothers. On the other hand, some studies have demonstrated either no or very little involvement of the placental tissue. The most common pathological changes reported are fetal and maternal vascular malformation, villitis of unknown etiology, thrombus formation in the intervillous space and sub-chorionic space, and chorangiosis. Reports on vertical transmission are less in number. The observations of this review present a strong base for the pathological involvement of the placenta in SARS-CoV-2 infected mothers. However, a smaller number of original studies have been done until now, and most of them have small sample sizes and lack matched control groups, which are the big limitations for drawing an effective conclusion at this stage. Antenatal care can be improved by a better understanding of the correlation between maternal SARS-CoV-2 infection and placental pathology in COVID-19.

The effect of the delta SARS-CoV-2 variant on maternal infection and pregnancy

A greater proportion of pregnant women with COVID-19 have mild disease compared with their non-pregnant counterparts. Paradoxically, however, they are at higher risk of developing severe disease, requiring respiratory support and admission to intensive care. The delta SARS-Cov-2 variant is associated with increased risk of hospitalization and morbidity in unvaccinated pregnant populations. However, it is not known whether the worse pregnancy outcomes associated with the delta variant are due to a direct effect of the virus on the pregnancy, or whether this effect is mediated through more severe maternal infection. Here, we synthesize studies of COVID-19 pregnancies, focusing on the different routes of SARS-CoV-2 infection of lung and placenta, and the mechanisms of syncytial formation for each SARS-CoV-2 variant. To delineate COVID-19 complications in pregnant women, future studies should explore whether the delta variant causes greater placental infection compared to other variants and contributes to increased syncytial formation.

Corona and Reproduction, or Why the Corona Vaccination Does Not Result in Infertility

Background As the COVID-19 pandemic persists and new vaccines are developed, concerns among the general public are growing that both infection with the SARS-CoV-2 virus and vaccinations against the coronavirus (mRNA vaccines) could lead to infertility or higher miscarriage rates. These fears are voiced particularly often by young adults of reproductive age. This review summarizes the current data on the impact of SARS-CoV-2 infection and corona vaccinations on female and male fertility, based on both animal models and human data.

Method A systematic literature search (PubMed, Embase, Web of Science) was carried out using the search terms “COVID 19, SARS-CoV-2, fertility, semen, sperm, oocyte, male fertility, female fertility, infertility”. After the search, original articles published between October 2019 and October 2021 were selected and reviewed.

Results Despite the use of very high vaccine doses in animal models, no negative impacts on fertility, the course of pregnancy, or fetal development were detected. In humans, no SARS-CoV-2 RNA was found in the oocytes/follicular fluid of infected women; similarly, no differences with regard to pregnancy rates or percentages of healthy children were found between persons who had recovered from the disease, vaccinated persons, and controls. Vaccination also had no impact on live-birth rates after assisted reproductive treatment. No viral RNA was detected in the semen of the majority of infected or still infectious men; however, a significant deterioration of semen parameters was found during semen analysis, especially after severe viral disease. None of the studies found that corona vaccines had any impact on male fertility.

Discussion Neither the animal models nor the human data presented in recent studies provide any indications that fertility decreases after being vaccinated against coronavirus. However, there is a growing body of evidence that severe SARS-CoV-2 infection has a negative impact on male fertility and there is clear evidence of an increased risk of complications among pregnant women with SARS-CoV-2 infection. The counseling offered to young adults should therefore take their fears and concerns seriously as well as providing a structured discussion of the current data.

Increased Placental Anti-Oxidant Response in Asymptomatic and Symptomatic COVID-19 Third-Trimester Pregnancies

Despite Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) -induced Oxidative Stress (OxS) being well documented in different organs, the molecular pathways underlying placental OxS in late-pregnancy women with SARS-CoV-2 infection are poorly understood. Herein, we performed an observational study to determine whether placentae of women testing positive for SARS-CoV-2 during the third trimester of pregnancy showed redox-related alterations involving Catalase (CAT) and Superoxide Dismutase (SOD) antioxidant enzymes as well as placenta morphological anomalies relative to a cohort of healthy pregnant women. Next, we evaluated if placental redox-related alterations and mitochondria pathological changes were correlated with the presence of maternal symptoms. We observed ultrastructural alterations of placental mitochondria accompanied by increased levels of oxidative stress markers Thiobarbituric Acid Reactive Substances (TBARS) and Hypoxia Inducible Factor-1 α (HIF-1α) in SARS-CoV-2 women during the third trimester of pregnancy. Importantly, we found an increase in placental CAT and SOD antioxidant enzymes accompanied by physiological neonatal outcomes. Our findings strongly suggest a placenta-mediated OxS inhibition in response to SARS-CoV-2 infection, thus contrasting the cytotoxic profile caused by Coronavirus Disease 2019 (COVID-19).

Stillbirth after COVID-19 in Unvaccinated Mothers Can Result from SARS-CoV-2 Placentitis, Placental Insufficiency, and Hypoxic Ischemic Fetal Demise, Not Direct Fetal Infection: Potential Role of Maternal Vaccination in Pregnancy

Stillbirth is a recently recognized complication of COVID-19 in pregnant women. Other congenitally transmitted infections from viruses, bacteria and parasites can cause stillbirth by infecting fetal organs following transplacental transmission of the agent from the maternal bloodstream. However, recent research on pregnant women with COVID-19 having stillbirths indicates that there is another mechanism of stillbirth that can occur in placentas infected with SARS-CoV-2. In these cases, viral infection of the placenta results in SARS-CoV-2 placentitis, a combination of concurrent destructive findings that include increased fibrin deposition which typically reaches the level of massive perivillous fibrin deposition, chronic histiocytic intervillositis and trophoblast necrosis. These three pathological lesions, in some cases together with placental hemorrhage, thrombohematomas and villitis, result in severe and diffuse placental parenchymal destruction. This pathology can involve greater than one-half of the placental volume, averaging 77% in the largest study of 68 cases, effectively rendering the placenta incapable of performing its function of oxygenating the fetus. This destructive placental process can lead to stillbirth and neonatal death via malperfusion and placental insufficiency which is independent of fetal infection. Fetal autopsies show no evidence that direct infection of fetal organs is contributory. Because all mothers examined have been unvaccinated, maternal vaccination may prevent viremia and consequent placental infection.

Placental Macrophage (Hofbauer Cell) Responses to Infection During Pregnancy: A Systematic Scoping Review

BACKGROUND

Congenital infection of the fetus via trans-placental passage of pathogens can result in severe morbidity and mortality. Even without transmission to the fetus, infection of the placenta itself is associated with pregnancy complications including pregnancy loss and preterm birth. Placental macrophages, also termed Hofbauer cells (HBCs), are fetal-origin macrophages residing in the placenta that are likely involved in responding to placental infection and protection of the developing fetus. As HBCs are the only immune cell present in the villous placenta, they represent one of the final opportunities for control of infection and prevention of passage to the developing fetus.

OBJECTIVE AND RATIONALE

The objective of this review was to provide a systematic overview of the literature regarding HBC responses during infection in pregnancy, including responses to viral, bacterial, and parasitic pathogens.

METHODS

PubMed and Scopus were searched on May 20th, 2021, with no limit on publication date, to identify all papers that have studied placental macrophages/Hofbauer cells in the context of infection. The following search strategy was utilized: (hofbauer* OR "hofbauer cells" OR "hofbauer cell" OR "placental macrophage" OR "placental macrophages") AND [infect* OR virus OR viral OR bacteri* OR parasite* OR pathogen* OR LPS OR "poly(i:c)" OR toxoplasm* OR microb* OR HIV)].

OUTCOMES

86 studies were identified for review. This included those that investigated HBCs in placentas from pregnancies complicated by maternal infection and in vitro studies investigating HBC responses to pathogens or Pathogen-Associated Molecular Patterns (PAMPs). HBCs can be infected by a variety of pathogens, and HBC hyperplasia was a common observation. HBCs respond to pathogen infection and PAMPs by altering their transcriptional, translational and secretion profiles. Co-culture investigations demonstrate that they can replicate and transmit pathogens to other cells. In other cases, they may eliminate the pathogen through a variety of mechanisms including phagocytosis, cytokine-mediated pathogen elimination, release of macrophage extracellular traps and HBC-antibody-mediated neutralization. HBC responses differ across gestation and may be influenced by pre-existing immunity. Clinical information, including gestational age at infection, gestational age of the samples, mode of sample collection and pregnancy outcome were missing for the majority of studies.

Low placental weight and altered metabolic scaling after severe acute respiratory syndrome coronavirus type 2 infection during pregnancy: a prospective multicentric study

Objectives

A higher risk of adverse pregnancy outcomes is associated with SARS-CoV-2 infection; this could be partially explained by an altered placental function. Because histopathology is often unspecific, we aimed to assess placental weight, birthweight/placental weight (b/p) ratio, and the metabolic scaling exponent ß, an indicator of normal fetal-placental growth, to analyze placental function.

Methods

We included 153 singleton pregnancies with SARS-CoV-2–positive PCR result who delivered at three referring hospitals in Switzerland. Placental weight and b/p ratio were compared to published reference charts. Logistic regression analysis investigated the role of time of infection and other confounding factors on placental weight. The scaling exponent β was compared to the reference value of 0.75.

Results

Placental weight was inferior or equal to the tenth centile in 42.5% (65 of 153) and to the third centile in 19% (29 of 153) of the cases. The risk of low placental weight was not influenced by the trimester in which infection occurred. The b/p ratio was >50th centile in 80.4% (123 of 153) of the cases. The incidence of foetal growth restriction, preeclampsia, and gestational diabetes was 11.8% (18 of 153), 3.3% (5 of 153), and 19.6% (30 of 153). Linear regression modelling revealed a pathologic metabolic scaling exponent β of 0.871 ± 0.064 (R² = 0.56).

Discussion

SARS-CoV-2 infection during pregnancy was associated with a higher incidence of low placental weight, an increased b/p ratio, and an abnormal scaling exponent β in our cohort. This could be particularly relevant for the still controversial issue of an increased stillbirth rate in SARS-CoV-2 infection during pregnancy. In this regard, intensified foetal surveillance should be mandatory in these pregnancies.

Delayed Antiviral Immune Responses in Severe Acute Respiratory Syndrome Coronavirus Infected Pregnant Mice

Sex differences in immune responses had been reported to correlate with different symptoms and mortality in the disease course of coronavirus disease 2019 (COVID-19). However, whether severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection interferes with females’ fertility and causes different symptoms among pregnant and non-pregnant females remains unknown. Here, we examined the differences in viral loads, SARS-CoV-2-specific antibody titers, proinflammatory cytokines, and levels of T cell activation after SARS-CoV-2 sub-lethal infection between pregnant and non-pregnant human Angiotensin-Converting Enzyme II (ACE2) transgenic mouse models. Both mice showed elevated levels of viral loads in the lung at 4 days post-infection (dpi). However, viral loads in the pregnant group remained elevated at 7 dpi while decreased in the non-pregnant group. Consistent with viral loads, increased production of proinflammatory cytokines was detected from the pregnant group, and the IgM or SARS-CoV-2-specific IgG antibody in serum of pregnant mice featured delayed elevation compared with non-pregnant mice. Moreover, by accessing kinetics of activation marker expression of peripheral T cells after infection, a lower level of CD8+ T cell activation was observed in pregnant mice, further demonstrating the difference of immune-response between pregnant and non-pregnant mice. Although vertical transmission did not occur as SARS-CoV-2 RNA was absent in the uterus and fetus from the infected pregnant mice, a lower pregnancy rate was observed when the mice were infected before embryo implantation after mating, indicating that SARS-CoV-2 infection may interfere with mice’s fertility at a specific time window. In summary, pregnant mice bear a weaker ability to eliminate the SARS-CoV-2 virus than non-pregnant mice, which was correlated with lower levels of antibody production and T cell activation.

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.

[Recommendations for SARS-CoV-2/COVID-19 during Pregnancy, Birth and Childbed - Update November 2021 (Long Version)]

Since the onset of the SARS-CoV-2 pandemic, the German Society of Gynecology and Obstetrics and the Society for Peri-/Neonatal Medicine have published and repeatedly updated recommendations for the management of SARS-CoV-2 positive pregnancies and neonates. As a continuation of existing recommendations, the current update addresses key issues related to the prenatal, perinatal, and postnatal care of pregnant women, women who have given birth, women who have recently given birth, women who are breastfeeding with SARS-CoV-2 and COVID-19, and their unborn or newborn infants, based on publications through September 2021. Recommendations and opinions were carefully derived from currently available scientific data and subsequently adopted by expert consensus. This guideline - here available in the long version - is intended to be an aid to clinical decision making. Interpretation and therapeutic responsibility remain with the supervising local medical team, whose decisions should be supported by these recommendations. Adjustments may be necessary due to the rapid dynamics of new evidence. The recommendations are supported by the endorsement of the professional societies: German Society for Perinatal Medicine (DGPM), German Society of Gynecology and Obstetrics (DGGG), German Society for Prenatal and Obstetric Medicine (DGPGM), German Society for Pediatric Infectiology (DGPI), Society for Neonatology and Pediatric Intensive Care Medicine (GNPI).

Perinatal outcomes of pregnant women having SARS-CoV-2 infection

OBJECTIVES

Aim of this study is to evaluate the prognosis of pregnant women having SARS-CoV-2 infection and investigate whether there was a difference in perinatal outcomes between pregnant women who had SARS-CoV-2 infection and those who did not.

MATERIALS AND METHODS

This prospective observational study was conducted with 116 singleton pregnancies. Cases enrolling in the study were divided into two groups. While those in the first group had a history of SARS-CoV-2 infection (n = 46) the second group consisted of healthy pregnant women (n = 70).

RESULTS

Emergency Cesarean section was performed on three SARS-CoV-2 infected pregnancies (30, 33 and 34 gestational weeks). Intensive care unit admission was required for all three cases after delivery and two of them died. Among the pregnancies that had an infection in the third trimester, 71.4% (n = 20) of them had delivery in 14 days after diagnosis and 17.4% (n = 8) of their newborns were followed up at newborn intensive care unit. Overall, only one newborn had a positive swab test result for SARS-CoV-2. There was no statistically significant difference between groups regarding their delivery week (37.02 ± 5.85 vs 38.5 ± 2.33). Similarly, there was no significant difference between groups, concerning mean age, parity, and birth weight (P = 0.707, P = 0.092, P = 0.334; P < 0.05). Furthermore, the difference between SARS-CoV-2 infected pregnancies that were followed up as inpatient or outpatient with respect to the delivery week and birth weight was not significant (p > 0.05). Also, APGAR 5 scores of hospitalized women (9.3 ± 1.1) were found to be lower than the outpatient group (9.8 ± 0.8) (P = 0.043; p < 0.05).

CONCLUSION

No significant difference was detected between groups in terms of the delivery week, birth weight, and APGAR scores. The inpatient group was found to have lower APGAR 5 scores.

Placental histopathology after SARS-CoV-2 infection in pregnancy: a systematic review and meta-analysis

OBJECTIVE

This study aimed to report the spectrum of placental pathology findings in pregnancies complicated by SARS-CoV-2 infection.

DATA SOURCES

MEDLINE, Embase, Google Scholar, and the Web of Science databases were searched up to August 11, 2021.

STUDY ELIGIBILITY CRITERIA

Histopathologic anomalies included maternal vascular malperfusion, fetal vascular malperfusion, acute inflammatory pathology, chronic inflammatory pathology, increased perivillous fibrin, and intervillous thrombosis. Moreover, subanalyses of symptomatic women only and high-risk pregnancies were performed.

METHODS

Histopathologic analysis of the placenta included gross examination, histopathology on hematoxylin and eosin, immunohistochemistry, fluorescence in situ hybridization, quantitative reverse transcription-polymerase chain reaction on placental tissue, and transmission electron microscope. Random-effect meta-analyses were used to analyze the data.

RESULTS

A total of 56 studies (1008 pregnancies) were included. Maternal vascular malperfusion was reported in 30.7% of placentas (95% confidence interval, 20.3-42.1), whereas fetal vascular malperfusion was observed in 27.08 % of cases (95% confidence interval, 19.2-35.6). Acute and chronic inflammatory pathologies were reported in 22.68% (95% confidence interval, 16.9-29.0) and 25.65% (95% confidence interval, 18.4-33.6) of cases, respectively. Increased perivillous fibrin was observed in 32.7% (95% confidence interval, 24.1-42.0) of placentas undergoing histopathologic analysis, whereas intervillous thrombosis was observed in 14.6% of cases (95% confidence interval, 9.7-20.2). Other placental findings, including a basal plate with attached myometrial fibers, microscopic accretism, villous edema, increased circulating nucleated red blood cells, or membranes with hemorrhage, were reported in 37.5% of cases (95% confidence interval, 28.0-47.5), whereas only 17.5% of cases (95% confidence interval, 10.9-25.2) did not present any abnormal histologic findings. The subanalyses according to maternal symptoms owing to SARS-CoV-2 infection or the presence of a high-risk pregnancy showed a similar distribution of the different histopathologic anomalies to that reported in the main analysis. Moreover, the risk of placental histopathologic anomalies was higher when considering only case-control studies comparing women with SARS-CoV-2 infection with healthy controls.

CONCLUSION

In pregnant women with SARS-CoV-2 infection, a significant proportion of placentas showed histopathologic findings, suggesting placental hypoperfusion and inflammation. Future multicenter prospective blinded studies are needed to correlate these placental lesions with pregnancy outcomes.

Fetal akinesia deformation sequence and massive perivillous fibrin deposition resulting in fetal death in six fetuses from one consanguineous couple, including literature review

Background

Massive perivillous fibrin deposition (MPFD) is associated with adverse pregnancy outcomes and is mainly caused by maternal factors with limited involvement of fetal or genetic causes. We present one consanguineous couple with six fetuses developing Fetal Akinesia Deformation Sequence (FADS) and MPFD, with a possible underlying genetic cause. This prompted a literature review on prevalence of FADS and MPFD.

Methods

Fetal ultrasound examination, motor assessment, genetic testing, postmortem examination, and placenta histology are presented (2009–2019). Literature was reviewed for the association between congenital anomalies and MPFD.

Results

All six fetuses developed normally during the first trimester. Thereafter, growth restriction, persistent flexed position, abnormal motility, and contractures in 4/6, consistent with FADS occurred. All placentas showed histologically confirmed MPFD. Genetic analyses in the five available cases showed homozygosity for two variants of unknown significance in two genes, VARS1 (OMIM*192150) and ABCF1 (OMIM*603429). Both parents are heterozygous for these variants. From 63/1999 manuscripts, 403 fetal outcomes were mobilized. In 14/403 fetuses, congenital abnormalities in association with MPFD were seen of which two fetuses with contractures/FADS facial anomalies.

Conclusion

The low prevalence of fetal contractures/FADS facial anomalies in association with MPFD in the literature review supports the possible fetal or genetic contribution causing FADS and MPFD in our family. This study with literature review supports the finding that fetal, fetoplacental, and/or genetic components may play a role in causing a part of MPFDs.

COVID-19 in pregnancy: placental pathological patterns and effect on perinatal outcome in five cases

INTRODUCTION

COVID-19, the disease caused by the novel coronavirus SARS-CoV-2, is a severe systemic thrombotic syndrome that emerged in 2019, with an ensuing pandemic. To evaluate the impact of this disease on placental tissue and perinatal outcome, histological, immunohistochemical and ultrastructural analyses of placental tissue were performed for five cases of pregnant women with COVID-19.

CASE REPORTS

All five pregnant women in this series developed COVID-19 in late pregnancy. Two patients experienced respiratory distress, and computed tomography revealed signs of pneumonia, with bilateral involvement, multiple lobular and subsegmental areas of consolidation and ground-glass opacities. Histological studies of placental tissue revealed the presence of slight signs of maternal vascular underperfusion (MVUs) or foetal vascular underperfusion (FVUs) lesions and mild inflammatory lesions. CD15 immunoreactivity in the placental tissue was low in all cases, demonstrating that in these cases there was not severe foetal hypoxia/asphyxia risk for newborns or distal vascular immaturity. In all cases examined, ultrastructural analyses showed spherical-like coronavirus particles with an electron intermediate-density core as well as projections from the surface as spike-like structures in the syncytiotrophoblasts. At term, all of the women delivered newborns who were negative for SARS-CoV-2 by nasopharyngeal testing in their first day of life. All newborns were exclusively breastfed and were discharged on the 3rd day of life.

CONCLUSIONS

In conclusion, placental patterns in pregnancy due to COVID-19 in the late stage of gestation indicate no evidence of vertical trans-placental SARS-CoV-2 transmission or a significant impact on the perinatal outcome of newborns, in both mild and more severe cases.

Fetal pulmonary artery Doppler evaluation in pregnant women after recovery from COVID-19

Objective

To evaluate fetal lung development using pulmonary artery Doppler in pregnant women who had recovered from COVID‐19.

Methods

The prospective case–control study included 41 pregnant women who had recovered from COVID‐19 and 43 healthy pregnant women (control group). All the women in the study group had been diagnosed with COVID‐19 and had completed a quarantine period.

Results

The demographic data of patients were similar in the groups (P > 0.05). Main pulmonary artery peak systolic velocity was higher and pulsatility indices were lower in pregnant women who recovered from COVID‐19 compared to the controls (P < 0.001, P = 0.001). Acceleration time, ejection time, and acceleration/ejection time ratio (PATET) of the fetal MPA Doppler were significantly decreased in pregnant women who recovered from COVID‐19 (P < 0.001, P = 0.036, and P = 0.002, respectively). The patients who had recovered from COVID‐19 were divided into two groups: those treated with expectant management and those treated in hospital. The pulmonary artery acceleration time and PATET ratio were significantly lower in the group treated in the hospital (P = 0.023 and P = 0.045, respectively).

Conclusion

Detailed Doppler evaluations of the pulmonary artery may help in evaluating the fetal adverse effects of COVID‐19 disease.

Detailed Doppler evaluations of the pulmonary artery may help in evaluating the fetal adverse effects of COVID‐19 disease.

Placental histopathology after SARS-CoV-2 infection in pregnancy: a systematic review and meta-analysis

OBJECTIVE

This study aimed to report the spectrum of placental pathology findings in pregnancies complicated by SARS-CoV-2 infection.

DATA SOURCES

MEDLINE, Embase, Google Scholar, and the Web of Science databases were searched up to August 11, 2021.

STUDY ELIGIBILITY CRITERIA

Histopathologic anomalies included maternal vascular malperfusion, fetal vascular malperfusion, acute inflammatory pathology, chronic inflammatory pathology, increased perivillous fibrin, and intervillous thrombosis. Moreover, subanalyses of symptomatic women only and high-risk pregnancies were performed.

METHODS

Histopathologic analysis of the placenta included gross examination, histopathology on hematoxylin and eosin, immunohistochemistry, fluorescence in situ hybridization, quantitative reverse transcription-polymerase chain reaction on placental tissue, and transmission electron microscope. Random-effect meta-analyses were used to analyze the data.

RESULTS

A total of 56 studies (1008 pregnancies) were included. Maternal vascular malperfusion was reported in 30.7% of placentas (95% confidence interval, 20.3-42.1), whereas fetal vascular malperfusion was observed in 27.08 % of cases (95% confidence interval, 19.2-35.6). Acute and chronic inflammatory pathologies were reported in 22.68% (95% confidence interval, 16.9-29.0) and 25.65% (95% confidence interval, 18.4-33.6) of cases, respectively. Increased perivillous fibrin was observed in 32.7% (95% confidence interval, 24.1-42.0) of placentas undergoing histopathologic analysis, whereas intervillous thrombosis was observed in 14.6% of cases (95% confidence interval, 9.7-20.2). Other placental findings, including a basal plate with attached myometrial fibers, microscopic accretism, villous edema, increased circulating nucleated red blood cells, or membranes with hemorrhage, were reported in 37.5% of cases (95% confidence interval, 28.0-47.5), whereas only 17.5% of cases (95% confidence interval, 10.9-25.2) did not present any abnormal histologic findings. The subanalyses according to maternal symptoms owing to SARS-CoV-2 infection or the presence of a high-risk pregnancy showed a similar distribution of the different histopathologic anomalies to that reported in the main analysis. Moreover, the risk of placental histopathologic anomalies was higher when considering only case-control studies comparing women with SARS-CoV-2 infection with healthy controls.

CONCLUSION

In pregnant women with SARS-CoV-2 infection, a significant proportion of placentas showed histopathologic findings, suggesting placental hypoperfusion and inflammation. Future multicenter prospective blinded studies are needed to correlate these placental lesions with pregnancy outcomes.

Defining Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Placentitis: A Report of 7 Cases with Confirmatory In Situ Hybridization, Distinct Histomorphologic Features, and Evidence of Complement Deposition

CONTEXT

-Case reports and rare case series have demonstrated variable placental pathology in the setting of maternal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In rare small studies demonstrating infection of the placental parenchyma, histologic manifestations have included variable degrees of histiocytic intervillositis, perivillous fibrin deposition, and syncytiotrophoblast necrosis.

OBJECTIVE

-To characterize the placental pathological features of SARS-CoV-2 infected placentas, irrespective of fetal-maternal transmission, and to examine the frequency of C4d activation in such cases.

DESIGN

-Retrospective study of seven placentas from mothers with active SARS-CoV-2 infection and placental infection as demonstrated by RNA in situ hybridization.

RESULTS

-Six placentas were from live-born neonates (5 singletons, 1 non-fused diamniotic-dichorionic twin placenta), and one was from a stillbirth. Five of the eight neonates (including the stillbirth) tested negative for SARS-CoV-2, and all were negative for neonatal infection. The remaining three neonates were well at time of discharge. All placentas were positive for SARS-CoV-2 infection by RNA in situ hybridization and demonstrated variable degrees of histiocytic intervillositis, perivillous fibrin deposition, and trophoblast necrosis. Three cases demonstrated features of fetal vascular malperfusion. CD68 highlighted intervillous histiocytes. C4d expression was present along the villous borders in 6 of 7 cases.

CONCLUSIONS

-SARS-CoV-2 placentitis is defined by the triad of histiocytic intervillositis, perivillous fibrin deposition, and trophoblast necrosis. The features may occur in cases without confirmed transplacental transmission. The damage caused by SARS-CoV-2 placentitis is likely mediated by complement activation.

SARS-CoV-2 colonization of maternal and fetal cells of the human placenta promotes alteration of local renin-angiotensin system

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection appears to increase the risk of adverse pregnancy outcomes, such as pre-eclampsia in pregnant women. The mechanism(s) by which this occurs remains unclear.

Methods

We investigated the pathophysiology of SARS-CoV-2 at maternal-fetal interface in pregnant women who tested positive for the virus using RNA in situ hybridization (viral RNA), immunohistochemistry, and hematoxylin and eosin staining. To investigate whether viral infection alters the renin angiotensin system (RAS) in placenta, which controls blood pressure, we treated human trophoblasts with recombinant spike protein or a live modified virus with a vesicular stomatitis viral backbone expressing spike protein (VSV-S).

Findings

Viral colonization was highest in maternal decidua, fetal trophoblasts, Hofbauer cells, and in placentas delivered prematurely. We localized SARS-CoV-2 to cells expressing angiotensin-converting enzyme 2 (ACE2) and demonstrate that infected placentas had significantly reduced ACE2. In response to both spike protein and VSV-S, cellular ACE2 decreased although angiotensin II receptor type 1 (AT₁R) increased with concomitant increase in soluble fms-like tyrosine kinase-1 (sFlt1). Viral infection decreased pro-angiogenic factors, AT₂R, and placental growth factor, which competitively binds to sFlt1. Sera from infected pregnant women had elevated levels of sFlt1 and angiotensin II type 1-receptor autoantibodies prior to delivery, both signatory markers of pre-eclampsia.

Conclusions

SARS-CoV-2 colonizes ACE2-expressing maternal and fetal cells in the placenta. Infection in pregnant women correlates with alteration of placental RAS. As RAS regulates blood pressure, SARS-CoV-2 infection may thus increase adverse hemodynamic outcomes, such as pre-eclampsia in pregnant women.

Funding

NIH/NICHD grants R01 HD091218 and 3R01HD091218-04S1 (RADx-UP Supplement).

Transient Early Fine Motor Abnormalities in Infants Born to COVID-19 Mothers Are Associated With Placental Hypoxia and Ischemia

Background: Long-term effects of Coronavirus Disease 2019 (COVID-19) on infants born to infected mothers are not clear. Fine motor skills are crucial for the development of infant emotional regulation, learning ability and social skills. Methods: Clinical information of 100 infants born to 98 mothers (COVID-19 n = 31, non-COVID-19 n = 67) were collected. Infants were follow-up up to 9 months post-partum. The placental tissues were examined for SARS-CoV-2 infection, pathological changes, cytokines, and mtDNA content. Results: Decreased placental oxygen and nutrient transport capacity were found in infected pregnant women. Increased IL-2, IL-6, TNF-α, and IFN-γ were detected in trophoblast cells and maternal blood of COVID-19 placentas. Elevated early fine motor abnormal-ities and increased serum TNI (troponin I) levels at delivery were observed in infants born to mothers with COVID-19. Increased abnormal mitochondria and elevated mtDNA content were found in the placentas from infected mothers. The placental mtDNA content of three infants with abnormal DDST were increased by 4, 7, and 10%, respectively, compared to the mean of the COVID-19 group. The Maternal Vascular Malperfusion (MVM), elevated cytokines and increased placental mtDNA content in mothers with COVID-19 might be associated with transient early fine motor abnormalities in infants. These abnormalities are only temporary, and they could be corrected by daily training. Conclusions: Babies born to COVID-19 mothers with mild symptoms appeared to have little or no excess long-term risks of abnormal physical and neurobehavioral development as compared with the infants delivered by non-COVID-19 mothers.