Respiratory Virus Infection During Pregnancy: Does It Matter?

The burden, pathogenesis, clinical outcomes, and treatment of common respiratory virus infections during pregnancy

Respiratory illnesses due to respiratory virus infections disproportionately impact pregnant individuals and their infants, leading to significant morbidity and mortality globally. Data describing the incidence and impact of these infections in pregnancy is sparse and more common for influenza and now severe acute respiratory syndrome coronavirus 2 with less data available on other respiratory virus infections in pregnancy. This lack of data is a result of limited prospective surveillance and issues surrounding the calculations of seroprevalence, as well as disproportionately low funding for reproductive health research. In this review article, we aimed to summarize available data on respiratory virus infections in pregnancy and identify gaps in the published literature.

Burden of Respiratory Syncytial Virus-Associated Acute Respiratory Infections During Pregnancy

BACKGROUND

With the licensure of maternal respiratory syncytial virus (RSV) vaccines in Europe and the United States, data are needed to better characterize the burden of RSV-associated acute respiratory infections (ARI) in pregnancy. The current study aimed to determine among pregnant individuals the proportion of ARI testing positive for RSV and the RSV incidence rate, RSV-associated hospitalizations, deaths, and perinatal outcomes.

METHODS

We conducted a systematic review, following PRISMA 2020 guidelines, using 5 databases (Medline, Embase, Global Health, Web of Science, and Global Index Medicus), and including additional unpublished data. Pregnant individuals with ARI who had respiratory samples tested for RSV were included. We used a random-effects meta-analysis to generate overall proportions and rate estimates across studies.

RESULTS

Eleven studies with pregnant individuals recruited between 2010 and 2022 were identified, most of which recruited pregnant individuals in community, inpatient and outpatient settings. Among 8126 pregnant individuals, the proportion with ARI that tested positive for RSV ranged from 0.9% to 10.7%, with a meta-estimate of 3.4% (95% confidence interval [CI], 1.9%-54%). The pooled incidence rate of RSV among pregnant individuals was 26.0 (95% CI, 15.8-36.2) per 1000 person-years. RSV hospitalization rates reported in 2 studies were 2.4 and 3.0 per 1000 person-years. In 5 studies that ascertained RSV-associated deaths among 4708 pregnant individuals, no deaths were reported. Three studies comparing RSV-positive and RSV-negative pregnant individuals found no difference in the odds of miscarriage, stillbirth, low birth weight, and small size for gestational age. RSV-positive pregnant individuals had higher odds of preterm delivery (odds ratio, 3.6 [95% CI, 1.3-10.3]).

CONCLUSIONS

Data on RSV-associated hospitalization rates are limited, but available estimates are lower than those reported in older adults and young children. As countries debate whether to include RSV vaccines in maternal vaccination programs, which are primarily intended to protect infants, this information could be useful in shaping vaccine policy decisions.

Intrauterine exposure to SARS-CoV-2 infection and early newborn brain development

Epidemiologic studies suggest that prenatal exposures to certain viruses may influence early neurodevelopment, predisposing offspring to neuropsychiatric conditions later in life. The long-term effects of maternal COVID-19 infection in pregnancy on early brain development, however, remain largely unknown. We prospectively enrolled infants in an observational cohort study for a single-site study in the Washington, DC Metropolitan Area from June 2020 to November 2021 and compared these infants to pre-pandemic controls (studied March 2014-February 2020). The primary outcomes are measures of cortical morphometry (tissue-specific volumes), along with global and regional measures of local gyrification index, and sulcal depth. We studied 210 infants (55 infants of COVID-19 unexposed mothers, 47 infants of COVID-19-positive mothers, and 108 pre-pandemic healthy controls). We found increased cortical gray matter volume (182.45 ± 4.81 vs. 167.29 ± 2.92) and accelerated sulcal depth of the frontal lobe (5.01 ± 0.19 vs. 4.40 ± 0.13) in infants of COVID-19-positive mothers compared to controls. We found additional differences in infants of COVID-19 unexposed mothers, suggesting both maternal viral exposures, as well as non-viral stressors associated with the pandemic, may influence early development and warrant ongoing follow-up.

Management and outcomes of pregnant ICU patients with severe COVID-19 pneumonia in Qatar: A retrospective cohort study

INTRODUCTION

Pregnant women are considered a high-risk group for COVID-19 due to their increased vulnerability to viral infections. The impact of COVID-19 on pregnant women is not well understood, and there is a need for data on managing severe COVID-19 in pregnant patients. This retrospective descriptive cohort study described the characteristics, hospital stay, interventions, and outcomes of pregnant patients admitted to the intensive care units (ICUs) with severe COVID-19 pneumonia in Qatar.

METHODS

Data were collected from medical records and chart reviews of pregnant women admitted to Hamad Medical Corporation (HMC) with COVID-19 pneumonia from March 01, 2020, to July 31, 2021. The inclusion criteria encompassed pregnant women with a positive polymerase chain reaction (PCR) antigen test or radiological changes at admission, requiring respiratory support, and hospitalized for more than 24 hours.

RESULTS

A total of 43 pregnant women were included in this study. Most patients were admitted during the first wave of the pandemic, with a median gestational age of 212 days [interquartile range 178-242 days] at presentation. The most common respiratory support methods were high-flow nasal cannula, non-invasive positive pressure ventilation, and invasive positive pressure ventilation. Convalescent plasma therapy was administered to 58% of patients, and tocilizumab was used in 28%. Renal replacement therapy was required by 4.6% of patients and 7% required extracorporeal membrane oxygenation.

CONCLUSION

This study provides valuable insights into the impact of COVID-19 on pregnant patients admitted to the ICUs in Qatar. The results suggest that pregnant patients with COVID-19 pneumonia require close monitoring and appropriate interventions to minimize adverse outcomes for both mother and fetus. The data may contribute to future guidelines and management strategies for severe COVID-19 in pregnant patients.

Acute respiratory infections among individuals seeking outpatient care in the states of Washington and Michigan by pregnancy status, 2011-2016

Background

Acute respiratory infections (ARIs) during pregnancy are associated with poor maternal and fetal outcomes.

Methods

Using U.S. Flu Vaccine Effectiveness Network data (2011-2016) from Washington and Michigan, we tested for respiratory viruses among pregnant and non-pregnant outpatients matched on age, site, and season (n = 191).

Results

Among all participants, detection of human coronaviruses and rhinovirus was common. We also observed differences in virus detection by pregnancy status; human coronaviruses and respiratory syncytial virus (RSV) were detected more frequently among pregnant and non-pregnant participants, respectively.

Conclusions

The role of respiratory viruses in maternal ARI morbidity should be further characterized to inform implementation of prevention interventions including maternal vaccines.

Maternal and Neonatal Outcomes Associated With COVID-19 Infection in Pregnant Mothers Admitted in Tertiary Care Hospital in Central State of India

In spite of various reports on perinatal outcomes of coronavirus disease 2019 (COVID-19) during pregnancies, the effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on unborn babies and pregnant mothers are still mysterious. The goal of our research is to examine the perceived fetomaternal outcomes of COVID-19 during pregnancy. A total of 396 pregnant women were admitted to the Department of Gynaecology and Obstetrics, Pt. JNM Medical College, Raipur, Chhattisgarh, India, during the period from July 20, 2020 to January 6, 2021. The presence of SARS-CoV-2 in different biological samples was recorded via positive quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) test results. All the newborns delivered from the infected pregnant mothers were tested as RT-PCR negative. Negative findings of RT-PCR for respiratory swabs of newborns, amniotic fluid, placental tissue, breast milk, vaginal swabs, and cord blood indicated no transmission of the virus from mother to baby. However, maternal outcomes, such as hospitalization (46.96%), preeclampsia (13.88%), pre-term birth (14.39%), prelabor rupture of membranes (PROM) before 34 weeks (3.78%), PROM before 37 weeks (2.77%), vaginal bleeding (4.29%), postpartum hemorrhage (2.52%), pregnancy-induced hypertension (1.51%), and neonatal outcomes such as low birth weight ≤1.5 kg (6.59) and 1.6-2.4 kg (39.34%), intrauterine deaths (IUD) (0.50%), fetal distress (22.33%), NICU admission (5.58%), meconium-stained liquor (14.46%), diarrhea (0.25%), and low APGAR score 4-6 at 1 min (20.54%), were observed. The results of the present study indicate that SARS-CoV-2-induced complications during pregnancy must be taken seriously. Intrauterine fetal deaths occurred at lower rates. There is no substantial proof of vertical perinatal transmission of the virus, as none of the neonates had tested positive for COVID-19.

Effects of Biological Sex and Pregnancy on SARS-CoV-2 Pathogenesis and Vaccine Outcomes

SARS-CoV-2 is the causative agent of COVID-19 in humans and has resulted in the death of millions of people worldwide. Similar numbers of infections have been documented in males and females; males, however, are more likely than females to be hospitalized, require intensive care unit, or die from COVID-19. The mechanisms that account for this are multi-factorial and are likely to include differential expression of ACE2 and TMPRSS2 molecules that are required for viral entry into hosts cells and sex differences in the immune response, which are due to modulation of cellular functions by sex hormones and differences in chromosomal gene expression. Furthermore, as comorbidities are also associated with poorer outcomes to SARS-CoV-2 infection and several comorbidities are overrepresented in males, these are also likely to contribute to the observed sex differences. Despite their relative better prognosis following infection with SARS-CoV-2, females do have poorer outcomes during pregnancy. This is likely to be due to pregnancy-induced changes in the immune system that adversely affect viral immunity and disruption of the renin-angiotensin system. Importantly, vaccination reduces the severity of disease in males and females, including pregnant females, and there is no evidence that vaccination has any adverse effects on the outcomes of pregnancy.

Immunology of Pregnancy and Systemic Consequences

Pregnancy is an immunological paradox, with renowned Nobel Prize winning transplantation biologist Sir Peter Brian Medawar being the first to introduce this concept back in 1953. This concept considers how the maternal immune system can tolerate the developing fetus, which is 50% antigenically foreign to the uterus. There have been significant advances in our understanding of the immune system in regulating fertility, pregnancy and in complications of these, and what was once considered a paradox can be seen as a highly evolved system. Indeed, the complexity of the maternal-fetal interface along with our ever-advancing knowledge of immune cells and mediators means that we have a better understanding of these interactions, with gaps still present.  This chapter will summarise the key aspects of the role of the immune system at each stage of pregnancy and highlight the recent advances in our knowledge.

Paradox of COVID-19 in pregnancy: are pregnant women more protected against or at elevated risk of severe COVID-19?

Many underlying medical conditions have been linked to worse COVID-19 prognosis. Based on reports on SARS-CoV-1 and Middle East respiratory syndrome infections, pregnancy has been considered a predisposing factor to severe COVID-19, with pregnant women being a high-risk group for several physiological reasons. Specifically, pregnant women undergo physiological adaptations that predispose them to severe respiratory viral diseases, including SARS-CoV-2. However, a significant amount of evidence suggests that the clinical outcome of COVID-19 among pregnant women is not different from the general population. In view of this, this report discusses the physiological conditions in pregnant women that adversely affect their immunity, cardiovascular homeostasis, and their endothelial and coagulopathic functions, thereby making them more prone to severe viral infections. We also discuss how these physiological adaptations appear to paradoxically offer protection against severe COVID-19 among pregnant women.

Bovine Animal Model for Studying the Maternal Microbiome, in utero Microbial Colonization and Their Role in Offspring Development and Fetal Programming

Recent developments call for further research on the timing and mechanisms involved in the initial colonization of the fetal/infant gut by the maternal microbiome and its role in Developmental Origins of Health and Disease (DOHaD). Although progress has been made using primarily preterm infants, ethical and legal constraints hinder research progress in embryo/fetal-related research and understanding the developmental and mechanistic roles of the maternal microbiome in fetal microbial imprinting and its long-term role in early-life microbiome development. Rodent models have proven very good for studying the role of the maternal microbiome in fetal programming. However, some inherent limitations in these animal models make it challenging to study perinatal microbial colonization from a biomedical standpoint. In this review, we discuss the potential use of bovine animals as a biomedical model to study the maternal microbiome, in utero microbial colonization of the fetal gut, and their impact on offspring development and DOHaD.

Viral Infections During Pregnancy: The Big Challenge Threatening Maternal and Fetal Health

Viral infections during pregnancy are associated with adverse pregnancy outcomes, including maternal and fetal mortality, pregnancy loss, premature labor, and congenital anomalies. Mammalian gestation encounters an immunological paradox wherein the placenta balances the tolerance of an allogeneic fetus with protection against pathogens. Viruses cannot easily transmit from mother to fetus due to physical and immunological barriers at the maternal-fetal interface posing a restricted threat to the fetus and newborns. Despite this, the unknown strategies utilized by certain viruses could weaken the placental barrier to trigger severe maternal and fetal health issues especially through vertical transmission, which was not fully understood until now. In this review, we summarize diverse aspects of the major viral infections relevant to pregnancy, including the characteristics of pathogenesis, related maternal-fetal complications, and the underlying molecular and cellular mechanisms of vertical transmission. We highlight the fundamental signatures of complex placental defense mechanisms, which will prepare us to fight the next emerging and re-emerging infectious disease in the pregnancy population.

Coronavirus Disease 2019 (COVID-19) and Pregnancy: A Narrative Review

A novel viral respiratory disease caused by severe acute respiratory syndrome, coronavirus 2 (SARS-COV-2), is responsible for a pandemic situation in the world. Pregnant women are susceptible to this virus due to physiologic changes in the immunologic system. The risk of some adverse pregnancy outcomes, such as death, stillbirth, preeclampsia, and intrauterine fetal distress, may increase in infected pregnant women. Infected women should be isolated and investigated, and they should admit to a designated hospital with adequate facilities and multi-disciplinary expertise to manage them. Furthermore, the chances of adverse neonatal complications, such as small for gestational age, large for gestational age, shortness of breath, thrombocytopenia with abnormal liver function, rapid heart rate, vomiting, and pneumothorax, may increase in an affected neonate. This study reviews the problems and guidelines of covid-19 in pregnancy.

Potential Neurocognitive Symptoms Due to Respiratory Syncytial Virus Infection

Respiratory infections are among the major public health burdens, especially during winter. Along these lines, the human respiratory syncytial virus (hRSV) is the principal viral agent causing acute lower respiratory tract infections leading to hospitalization. The pulmonary manifestations due to hRSV infection are bronchiolitis and pneumonia, where the population most affected are infants and the elderly. However, recent evidence suggests that hRSV infection can impact the mother and fetus during pregnancy. Studies have indicated that hRSV can infect different cell types from the placenta and even cross the placenta barrier and infect the fetus. In addition, it is known that infections during the gestational period can lead to severe consequences for the development of the fetus due not only to a direct viral infection but also because of maternal immune activation (MIA). Furthermore, it has been described that the development of the central nervous system (CNS) of the fetus can be affected by the inflammatory environment of the uterus caused by viral infections. Increasing evidence supports the notion that hRSV could invade the CNS and infect nervous cells, such as microglia, neurons, and astrocytes, promoting neuroinflammation. Moreover, it has been described that the hRSV infection can provoke neurological manifestations, including cognitive impairment and behavioral alterations. Here, we will review the potential effect of hRSV in brain development and the potential long-term neurological sequelae.

Sex Differences in Respiratory Viral Pathogenesis and Treatments

Biological sex affects the outcome of diverse respiratory viral infections. The pathogenesis of respiratory infections caused by viruses ranging from respiratory syncytial virus to influenza viruses and severe acute respiratory syndrome coronavirus 2 differs between the sexes across the life course. Generally, males are more susceptible to severe outcomes from respiratory viral infections at younger and older ages. During reproductive years (i.e., after puberty and prior to menopause), females are often at greater risk than males for severe outcomes. Pregnancy and biological sex affect the pathogenesis of respiratory viral infections. In addition to sex differences in the pathogenesis of disease, there are consistent sex differences in responses to treatments, with females often developing greater immune responses but experiencing more adverse reactions than males. Animal models provide mechanistic insights into the causes of sex differences in respiratory virus pathogenesis and treatment outcomes, where available. Expected final online publication date for the Annual Review of Virology, Volume 8 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Knowledge and Attitude regarding COVID-19 among Pregnant Women in Southwestern Iran in the Early Period of its Outbreak: A Cross-Sectional Study

Both knowledge and attitude can play key roles in the prevention of novel COVID-19. This cross-sectional study was conducted on a statistical sample of pregnant women in southwestern Iran between March and April 2020 to evaluate their knowledge and attitude toward this condition. So, pregnant mothers registered in antenatal clinics affiliated to Shiraz University of Medical Sciences were called and asked to fill in a three-part online questionnaire including sociodemographic characteristics, obstetric/medical history, and knowledge/attitude toward COVID-19. P-values < 0.05 were considered statistically significant. The mean score of knowledge among 540 respondents was 34 (±4.1) out of 43. Also, 44.3% answered more than 80% of the items correctly. Higher knowledge scores were accordingly associated with marriage duration, area of residence, health insurance coverage, socioeconomic status (SES), and self-rated health status. However, a strong relationship was found between knowledge, SES, and health insurance coverage with reference to multivariate analysis results. Moreover, majority of the pregnant women and their households expressed their concern about using preventive measures against COVID-19. Although most respondents were moderately worried about becoming infected with COVID-19, 264 (48.9%) cases reported that they were very much anxious about their newborns being infected with COVID-19 and 388 (71.9%) individuals asserted that they were worried about their mortality due to this infection. Besides, most mothers maintained that they had some degrees of rumination, which could interfere with their routine daily chores. Hence, health policy-makers should pay much focus on educating pregnant mothers to help them prevent mental exhaustion.