Influenza A/H1N1v in pregnancy: an investigation of the characteristics and management of affected women and the relationship to pregnancy outcomes for mother and infant

Defining the balance between optimal immunity and immunopathology in influenza virus infection

Influenza A viruses remain a global threat to human health, with continued pandemic potential. In this Review, we discuss our current understanding of the optimal immune responses that drive recovery from influenza virus infection, highlighting the fine balance between protective immune mechanisms and detrimental immunopathology. We describe the contribution of innate and adaptive immune cells, inflammatory modulators and antibodies to influenza virus-specific immunity, inflammation and immunopathology. We highlight recent human influenza virus challenge studies that advance our understanding of susceptibility to influenza and determinants of symptomatic disease. We also describe studies of influenza virus-specific immunity in high-risk groups following infection and vaccination that inform the design of future vaccines to promote optimal antiviral immunity, particularly in vulnerable populations. Finally, we draw on lessons from the COVID-19 pandemic to refocus our attention to the ever-changing, highly mutable influenza A virus, predicted to cause future global pandemics.

Variations across Europe in hospitalization and management of pregnant women with SARS-CoV-2 during the initial phase of the pandemic: Multi-national population-based cohort study using the International Network of Obstetric Survey Systems (INOSS)

INTRODUCTION

The majority of data on COVID-19 in pregnancy are not from sound population-based active surveillance systems.

MATERIAL AND METHODS

We conducted a multi-national study of population-based national or regional prospective cohorts using standardized definitions within the International Network of Obstetric Survey systems (INOSS). From a source population of women giving birth between March 1 and August 31, 2020, we included pregnant women admitted to hospital with a positive SARS-CoV-2 PCR test ≤7 days prior to or during admission and up to 2 days after birth. The admissions were further categorized as COVID-19-related or non-COVID-19-related. The primary outcome of interest was incidence of COVID-19-related hospital admission. Secondary outcomes included severe maternal disease (ICU admission and mechanical ventilation) and COVID-19-directed medical treatment.

RESULTS

In a source population of 816 628 maternities, a total of 2338 pregnant women were admitted with SARS-CoV-2; among them 940 (40%) were COVID-19-related admissions. The pooled incidence estimate for COVID-19-related admission was 0.59 (95% confidence interval 0.27-1.02) per 1000 maternities, with notable heterogeneity across countries (I2  = 97.3%, P = 0.00). In the COVID-19 admission group, between 8% and 17% of the women were admitted to intensive care, and 5%-13% needed mechanical ventilation. Thromboprophylaxis was the most frequent treatment given during COVID-19-related admission (range 14%-55%). Among 908 infants born to women in the COVID-19-related admission group, 5 (0.6%) stillbirths were reported.

CONCLUSIONS

During the initial months of the pandemic, we found substantial variations in incidence of COVID-19-related admissions in nine European countries. Few pregnant women received COVID-19-directed medical treatment. Several barriers to rapid surveillance were identified. Investment in robust surveillance should be prioritized to prepare for future pandemics.

The perinatal health challenges of emerging and re-emerging infectious diseases: A narrative review

The world has seen numerous infectious disease outbreaks in the past decade. In many cases these outbreaks have had considerable perinatal health consequences including increased risk of preterm delivery (e.g., influenza, measles, and COVID-19), and the delivery of low birth weight or small for gestational age babies (e.g., influenza, COVID-19). Furthermore, severe perinatal outcomes including perinatal and infant death are a known consequence of multiple infectious diseases (e.g., Ebola virus disease, Zika virus disease, pertussis, and measles). In addition to vaccination during pregnancy (where possible), pregnant women, are provided some level of protection from the adverse effects of infection through community-level application of evidence-based transmission-control methods. This review demonstrates that it takes almost 2 years for the perinatal impacts of an infectious disease outbreak to be reported. However, many infectious disease outbreaks between 2010 and 2020 have no associated pregnancy data reported in the scientific literature, or pregnancy data is reported in the form of case-studies only. This lack of systematic data collection and reporting has a negative impact on our understanding of these diseases and the implications they may have for pregnant women and their unborn infants. Monitoring perinatal health is an essential aspect of national and global healthcare strategies as perinatal life has a critical impact on early life mortality as well as possible effects on later life health. The unpredictable nature of emerging infections and the potential for adverse perinatal outcomes necessitate that we thoroughly assess pregnancy and perinatal health implications of disease outbreaks and their public health interventions in tandem with outbreak response efforts. Disease surveillance programs should incorporate perinatal health monitoring and health systems around the world should endeavor to continuously collect perinatal health data in order to quickly update pregnancy care protocols as needed.

Viral pulmonary infection in pregnancy - Including COVID-19, SARS, influenza A, and varicella

The COVID-19 pandemic has been at the forefront of medicine over the last few years. Pregnant women are often exposed to infectious agents that can be harmful not only to the mother but also to the foetus. Moreover, changes during pregnancy means that pregnant women have increased vulnerability to viral infections, especially pulmonary infections. Epidemiological studies have shown a link between maternal viral infections and miscarriage, preterm birth as well as congenital defects. With potential poor outcomes for both women and their newborns, having a good understanding of the presentation and management of these viral pulmonary infections is essential. The increased risk of adverse outcomes has been highlighted during the COVID-19, SARS and H1N1 influenza pandemics.

Psychosocial outcomes of COVID-19 pandemic on healthcare workers in maternity services

AIM

We investigated the effects of the COVID-19 outbreak on social support and anxiety levels in healthcare professionals working in maternity services situated in Trabzon, Turkey.

MATERIALS AND METHODS

Our study was designed retrospectively and observationally. Social support to the participants was measured using a scale called the multidimensional scale of perceived social support (MSPSS). State anxiety scale (STAI TX-1) and trait anxiety scale (STAI TX-2) were used to determine the level of anxiety. All scales were measured before and during the pandemic. Independent t-test and one-way ANOVA were used to analyze the data where p < 0.05 was considered significant.

RESULTS

The participants' demographic data (n = 96) included the mean age of doctors (n = 30), midwives (n = 34), and nurses (n = 32) which were 41.38 ± 4.16/38.58 ± 1.79/37.34 ± 2.19, respectively. Mean gravida was 1.69 ± 2.87/2.23 ± 0.12/2.31 ± 0.14, respectively. Mean BMI was 24.69 ± 2.87/26.04 ± 0.8/25.69 ± 1.98 in the same order (p > 0.05). The total mean values of the MSPSS, STAI TX-1, STAI TX-2 scales before and during the pandemic were found as 66.55 ± 6.63 - 55.25 ± 4.76, 36.71 ± 10.04 - 50.08 ± 11.65, 37.33 ± 8.09 - 53.32 ± 9.94, respectively. A significant difference was found for the mean of all scales amongst the groups (p < 0.05).

CONCLUSION

During the COVID-19 pandemic, a significant number of healthcare workers were deprived of social support and their anxiety levels increased.

Effects of Vertical Transmission of Respiratory Viruses to the Offspring

Overt and subclinical maternal infections in pregnancy can have multiple and significant pathological consequences for the developing fetus, leading to acute perinatal complications and/or chronic disease throughout postnatal life. In this context, the current concept of pregnancy as a state of systemic immunosuppression seems oversimplified and outdated. Undoubtedly, in pregnancy the maternal immune system undergoes complex changes to establish and maintain tolerance to the fetus while still protecting from pathogens. In addition to downregulated maternal immunity, hormonal changes, and mechanical adaptation (e.g., restricted lung expansion) make the pregnant woman more susceptible to respiratory pathogens, such as influenza virus, respiratory syncytial virus (RSV), and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Depending on the infectious agent and timing of the infection during gestation, fetal pathology can range from mild to severe, and even fatal. Influenza is associated with a higher risk of morbidity and mortality in pregnant women than in the general population, and, especially during the third trimester of pregnancy, mothers are at increased risk of hospitalization for acute cardiopulmonary illness, while their babies show higher risk of complications such as prematurity, respiratory and neurological illness, congenital anomalies, and admission to neonatal intensive care. RSV exposure in utero is associated with selective immune deficit, remodeling of cholinergic innervation in the developing respiratory tract, and abnormal airway smooth muscle contractility, which may predispose to postnatal airway inflammation and hyperreactivity, as well as development of chronic airway dysfunction in childhood. Although there is still limited evidence supporting the occurrence of vertical transmission of SARS-CoV-2, the high prevalence of prematurity among pregnant women infected by SARS-CoV-2 suggests this virus may alter immune responses at the maternal-fetal interface, affecting both the mother and her fetus. This review aims at summarizing the current evidence about the short- and long-term consequences of intrauterine exposure to influenza, RSV, and SARS-CoV-2 in terms of neonatal and pediatric outcomes.

Characteristics and Outcomes of Hospitalized Pregnant Women With Influenza, 2010 to 2019 : A Repeated Cross-Sectional Study

BACKGROUND

Pregnant women may be at increased risk for severe influenza-associated outcomes.

OBJECTIVE

To describe characteristics and outcomes of hospitalized pregnant women with influenza.

DESIGN

Repeated cross-sectional study.

SETTING

The population-based U.S. Influenza Hospitalization Surveillance Network during the 2010-2011 through 2018-2019 influenza seasons.

PATIENTS

Pregnant women (aged 15 to 44 years) hospitalized with laboratory-confirmed influenza identified through provider-initiated or facility-based testing practices.

MEASUREMENTS

Clinical characteristics, interventions, and in-hospital maternal and fetal outcomes were obtained through medical chart abstraction. Multivariable logistic regression was used to evaluate the association between influenza A subtype and severe maternal influenza-associated outcomes, including intensive care unit (ICU) admission, mechanical ventilation, extracorporeal membrane oxygenation, or in-hospital death.

RESULTS

Of 9652 women aged 15 to 44 years and hospitalized with influenza, 2690 (27.9%) were pregnant. Among the 2690 pregnant women, the median age was 28 years, 62% were in their third trimester, and 42% had at least 1 underlying condition. Overall, 32% were vaccinated against influenza and 88% received antiviral treatment. Five percent required ICU admission, 2% required mechanical ventilation, and 0.3% (n = 8) died. Pregnant women with influenza A H1N1 were more likely to have severe outcomes than those with influenza A H3N2 (adjusted risk ratio, 1.9 [95% CI, 1.3 to 2.8]). Most women (71%) were still pregnant at hospital discharge. Among 754 women who were no longer pregnant at discharge, 96% had a pregnancy resulting in live birth, and 3% experienced fetal loss.

LIMITATION

Maternal and fetal outcomes that occurred after hospital discharge were not captured.

CONCLUSION

Over 9 influenza seasons, one third of reproductive-aged women hospitalized with influenza were pregnant. Influenza A H1N1 was associated with more severe maternal outcomes. Pregnant women remain a high-priority target group for vaccination.

PRIMARY FUNDING SOURCE

Centers for Disease Control and Prevention.

Morbidity of late-season influenza during pregnancy

BACKGROUND

In the Northern Hemisphere, influenza season typically starts in December and lasts through March. Pregnant people are at increased risk for influenza-related morbidity and mortality. Potentially, new viral strains or reduced provider suspicion leading to delayed diagnosis of late-season influenza could result in an increased risk of severe infection.

OBJECTIVE

This study aimed to assess the incidence and morbidity associated with late-season influenza in pregnancy, compared with influenza in other seasons.

STUDY DESIGN

This was a retrospective cohort study using the 2007-2018 National Inpatient Sample. Pregnant patients with discharge diagnosis codes consistent with influenza infection were compared on the basis of hospital admission quarter (quarter 1: October to December; quarter 2: January to March; quarter 3: April to June; quarter 4: July to September), with quarter 3 defined as "late-season." The primary outcome was the severe maternal morbidity composite defined by the Centers for Disease Control and Prevention. The secondary outcomes included sepsis, shock, acute renal failure, acute heart failure, temporary tracheostomy, and invasive mechanical ventilation. Associations between outcomes and quarter of infection were adjusted for age, hospitalization type (antepartum, delivery, or postpartum), and comorbid conditions using relative risk regression, weighted to reflect the National Inpatient Sample design.

RESULTS

Of 7355 hospitalizations, corresponding to a weighted national estimate of 36,042, 2266 (30.8%) occurred in quarter 1, 4051 (55.0%) in quarter 2, 633 (8.6%) in quarter 3, and 405 (5.5%) in quarter 4. A nonsignificant trend toward higher rates of severe maternal morbidity was seen in the "late-season" compared with other quarters (13.9% [quarter 3] vs 10.5% [quarter 1] vs 12.1% [quarter 2] vs 13.6% [quarter 4]; P=.07). Moreover, sepsis was more common in patients with late-season influenza (8.0% [quarter 3] vs 4.8% [quarter 1] vs 5.8% [quarter 2] vs 5.9% [quarter 4]; P=.03). In the adjusted analyses, patients with late-season influenza had a 1.34 (95% confidence interval, 1.01-1.78) higher risk of severe maternal morbidity and 1.57 (95% confidence interval, 1.06-2.32) higher risk of sepsis than patients with influenza in quarter 1.

CONCLUSION

Influenza infection between April and June, that is, late-season influenza, is associated with a higher risk of severe maternal morbidity and sepsis in pregnant patients. Obstetrical providers must continue to have awareness and suspicion for influenza infection during these months.

Safety, Immunogenicity, Efficacy and Effectiveness of Inactivated Influenza Vaccines in Healthy Pregnant Women and Children Under 5 Years: An Evidence-Based Clinical Review

Annual influenza vaccination is often recommended for pregnant women and young children to reduce the risk of severe influenza. However, most studies investigating the safety, immunogenicity, and efficacy or effectiveness of influenza vaccines are conducted in healthy adults. In this evidence-based clinical review, we provide an update on the safety profile, immunogenicity, and efficacy/effectiveness of inactivated influenza vaccines (IIVs) in healthy pregnant women and children <5 years old. Six electronic databases were searched until May 27, 2021. We identified 3,731 articles, of which 93 met the eligibility criteria and were included. The IIVs were generally well tolerated in pregnant women and young children, with low frequencies of adverse events following IIV administration; however, continuous vaccine safety monitoring systems are necessary to detect rare adverse events. IIVs generated good antibody responses, and the seroprotection rates after IIVs were moderate to high in pregnant women (range = 65%-96%) and young children (range = 50%-100%), varying between the different influenza types/subtypes and seasons. Studies show vaccine efficacy/effectiveness values of 50%-70% in pregnant women and 20%-90% in young children against lab-confirmed influenza, although the efficacy/effectiveness depended on the study design, host factors, vaccine type, manufacturing practices, and the antigenic match/mismatch between the influenza vaccine strains and the circulating strains. Current evidence suggests that the benefits of IIVs far outweigh the potential risks and that IIVs should be recommended for pregnant women and young children.

COVID-19 in pregnancy-characteristics and outcomes of pregnant women admitted to hospital because of SARS-CoV-2 infection in the Nordic countries

Introduction

Population‐based studies about the consequences of SARS‐CoV‐2 infection (COVID‐19) in pregnancy are few and have limited generalizability to the Nordic population and healthcare systems.

Material and methods

This study examines pregnant women with COVID‐19 in the five Nordic countries. Pregnant women were included if they were admitted to hospital between 1 March and 30 June 2020 and had a positive SARS‐CoV‐2 PCR test ≤14 days prior to admission. Cause of admission was classified as obstetric or COVID‐19‐related.

Results

In the study areas, 214 pregnant women with a positive test were admitted to hospital, of which 56 women required hospital care due to COVID‐19. The risk of admission due to COVID‐19 was 0.4/1000 deliveries in Denmark, Finland and Norway, and 3.8/1000 deliveries in the Swedish regions. Women hospitalized because of COVID‐19 were more frequently obese (p < 0.001) and had a migrant background (p < 0.001) compared with the total population of women who delivered in 2018. Twelve women (21.4%) needed intensive care. Among the 56 women admitted due to COVID‐19, 48 women delivered 51 infants. Preterm delivery (n = 12, 25%, p < 0.001) and cesarean delivery (n = 21, 43.8%, p < 0.001) were more frequent in women with COVID‐19 compared with women who delivered in 2018. No maternal deaths, stillbirths or neonatal deaths were reported.

Conclusions

The risk of admission due to COVID‐19 disease in pregnancy was low in the Nordic countries. A fifth of the women required intensive care and we observed higher rates of preterm and cesarean deliveries. National public health policies appear to have had an impact on the risk of admission due to severe COVID‐19 disease in pregnancy. Nordic collaboration is important in collecting robust data and assessing rare outcomes.

Incidence, risk factors and impact of seasonal influenza in pregnancy: A national cohort study

BACKGROUND

Pregnant women are particularly vulnerable to severe infection from influenza resulting in poor neonatal outcomes. The majority of evidence relates to pandemic 2009 A/H1N1 influenza. The objective of this study was to describe the characteristics and outcomes of pregnant women hospitalised with seasonal influenza.

METHODS

This national, prospective, observational cohort study used the UK Obstetric Surveillance System (UKOSS) to identify all pregnant women admitted to hospital between 01/11/2016 and 31/10/2018 with laboratory confirmed influenza at any gestation and up to two days after giving birth. These were compared to women admitted to give birth that did not have influenza. Baseline characteristics, immunization status, maternal and perinatal outcomes were compared.

RESULTS

There were 405 women admitted to hospital with laboratory confirmed influenza in pregnancy: 2.7 per 10,000 maternities. Compared to 694 comparison women, women with influenza were less likely to be professionally employed (aOR 0.59, 95%CI 0.39-0.89) or immunised in the relevant season (aOR 0·59, 0·39-0·89) and more likely to have asthma (aOR 2.42, 1.30-4.49) or have had a previous pregnancy complication (aOR 2·47, 1·33-4·61). They were more likely to be admitted to intensive care (aOR 21.3, 2.78-163.1) and to have a cesarean birth (aOR 1·42, 1·02-1.98). Their babies were more likely to be admitted to neonatal intensive care (aOR 1.86, 1·01-3·42).

CONCLUSIONS

Immunization reduces the risk of hospitalisation with influenza in pregnancy which is associated with increased risk of morbidity for both the mother and baby. There is a continued need to increase awareness of safety and effectiveness of immunization in pregnancy and provision within antenatal care settings, especially for high-risk groups.

Placental origins of neonatal diseases: toward a precision medicine approach

The placenta is the single most reliable source for precise information on intrauterine environment, as well as maternal and fetal health. It mediates the physiology of two distinct yet highly interconnected individuals. The pathology that develops in the placenta, and the adaptations the placenta undergoes to mitigate this pathology, may influence the later life health of the mother and baby. Pathological placental examination provides a unique opportunity to explore and understand the intrauterine environment, as well as providing a record of events that may be associated with adverse pregnancy outcomes. A number of placental lesions have been described in association with various neonatal morbidities. The purpose of this review is to summarize the evidence for the association of placental pathologic lesions with neurodevelopmental outcomes infants with specific neonatal morbidities, including (1) neonatal encephalopathy, (2) bronchopulmonary dysplasia, (3) congenital heart diseases, and (4) autism spectrum disorders. For each of these disease processes, we will also propose specific research priorities in future studies. We conclude with a hospital-specific protocol for triaging which placentas should receive histological evaluation as a fundamental first step for the field of neuroplacentology to guide precision-based therapeutic approaches in the affected newborns. IMPACT: The purpose of this review is to summarize the evidence for placental origins of neonatal diseases. We propose specific research priorities in the field of neuroplacentology in future studies. We also present a targeted hospital-based approach for triaging which placentas should receive histological evaluation.

Lessons learned from the A (H1N1) influenza pandemic

Influenza in pregnancy is a common condition that is associated with an increased risk of hospital admission. Women with comorbidities are at a greater risk of severe outcomes. There are substantial gaps in our knowledge of the impact of severe influenza on perinatal outcomes, particularly in low- and middle-income countries, but preterm birth, fetal death, infant respiratory infection and hospital admission may be increased. Thus, influenza is a major burden on health services. Immunisation is cost-effective, safe and effective in preventing influenza in pregnant women and their infants but policies and uptake vary worldwide. Operational challenges and concern over the safety, efficacy and necessity of immunisation are common, and there is a lack of evidence on how to overcome these barriers. This review identifies learning points that are relevant to the current coronavirus disease-2019 pandemic through describing the epidemiology and impact of seasonal and A(H1N1)pdm09 influenza in pregnancy, alongside the effectiveness and use of immunisation.

Women's perceptions of COVID-19 and their healthcare experiences: a qualitative thematic analysis of a national survey of pregnant women in the United Kingdom

Background

The aim of this national survey was to explore pregnant women’s perceptions of COVID-19 and their healthcare experiences.

Methods

Through patient and public involvement, a questionnaire was developed and advertised via the BBC website, Twitter and other online media during May 2020. The findings were analysed by qualitative thematic analysis. Women who are currently pregnant, or who have delivered during the COVID-19 pandemic were invited to partake in a national online survey.

Results

One thousand four hundred fifty-one participants replied to the online questionnaire. Participants provided significant insight into the perceived barriers to seeking healthcare during this pandemic. These include ‘not wanting to bother anyone’, ‘lack of wider support from allied healthcare workers’ and the influence of the media. Other concerns included the use of virtual clinics antenatally and their acceptability to patients, the presence of birthing partners, and the way in which information is communicated about rapidly changing and evolving services. The influence of the media has also had a significant impact on the way women perceive hospital care in light of COVID-19 and for some, this has shaped whether they would seek help.

Conclusions

This is the first ever reported study in the United Kingdom to explore pregnant women’s perceptions of COVID-19 and their subsequent healthcare experiences. It has also provided insight into perceived barriers into seeking care as well as maternal concerns antenatally, intrapartum and postpartum.

Innate Immune Responses to Acute Viral Infection During Pregnancy

Immunological adaptations in pregnancy allow maternal tolerance of the semi-allogeneic fetus but also increase maternal susceptibility to infection. At implantation, the endometrial stroma, glands, arteries and immune cells undergo anatomical and functional transformation to create the decidua, the specialized secretory endometrium of pregnancy. The maternal decidua and the invading fetal trophoblast constitute a dynamic junction that facilitates a complex immunological dialogue between the two. The decidual and peripheral immune systems together assume a pivotal role in regulating the critical balance between tolerance and defense against infection. Throughout pregnancy, this equilibrium is repeatedly subjected to microbial challenge. Acute viral infection in pregnancy is associated with a wide spectrum of adverse consequences for both mother and fetus. Vertical transmission from mother to fetus can cause developmental anomalies, growth restriction, preterm birth and stillbirth, while the mother is predisposed to heightened morbidity and maternal death. A rapid, effective response to invasive pathogens is therefore essential in order to avoid overwhelming maternal infection and consequent fetal compromise. This sentinel response is mediated by the innate immune system: a heritable, highly evolutionarily conserved system comprising physical barriers, antimicrobial peptides (AMP) and a variety of immune cells—principally neutrophils, macrophages, dendritic cells, and natural killer cells—which express pattern-receptors that detect invariant molecular signatures unique to pathogenic micro-organisms. Recognition of these signatures during acute infection triggers signaling cascades that enhance antimicrobial properties such as phagocytosis, secretion of pro-inflammatory cytokines and activation of the complement system. As well as coordinating the initial immune response, macrophages and dendritic cells present microbial antigens to lymphocytes, initiating and influencing the development of specific, long-lasting adaptive immunity. Despite extensive progress in unraveling the immunological adaptations of pregnancy, pregnant women remain particularly susceptible to certain acute viral infections and continue to experience mortality rates equivalent to those observed in pandemics several decades ago. Here, we focus specifically on the pregnancy-induced vulnerabilities in innate immunity that contribute to the disproportionately high maternal mortality observed in the following acute viral infections: Lassa fever, Ebola virus disease (EVD), dengue fever, hepatitis E, influenza, and novel coronavirus infections.

Adverse outcomes in SAR-CoV-2 (COVID-19) and SARS virus related pregnancies with probable vertical transmission

The global severe acute respiratory syndrome-related coronavirus SARS-CoV-2 (COVID-19) pandemic has had an unprecedented impact on all aspects of daily life and healthcare. Information on the infection risks for pregnant women and their offspring have so far been limited to small case series, until a large UK report on 427 SARS-CoV-2 infected pregnant women was published. Previous SARS epidemic experiences were drawn upon. Diagnostic use of real time polymerase chain reaction (RT-PCR) and IgG and IgM antibody tests are fraught with concerns of non-validation and false negative results, as are sampling methodologies. Virtually no information on controls accompany these reports. Infection of the mother and baby has serious implications for obstetric and neonatal care. Information on early and late stage pregnancy infection and the relationship to severity of infection on fetal development is both useful and clearly warranted. An increasing number of reports centre around mildly infected women showing no evidence of fetal infection while a few reports suggesting vertical transmission require further validation. Vertical transmission from mother to baby however small would have profound health implications for obstetric and neonatal care and fetal abnormalities. Some data suggesting intrapartum vertical transmission from mother to baby cannot be dismissed given the lack of controls and limitations of diagnostic viral tests. This analysis covers some key early reports addressing pregnancy outcomes following SARS-CoV-2 infection.

Provision of obstetrics and gynaecology services during the COVID-19 pandemic: a survey of junior doctors in the UK National Health Service

Objective

The coronavirus disease 2019 (COVID‐19) pandemic is disrupting health services worldwide. We aimed to evaluate the provision of obstetrics and gynaecology services in the UK during the acute phase of the COVID‐19 pandemic.

Design

Interview‐based national survey.

Setting

Women's healthcare units in the National Health Service.

Population

Junior doctors in obstetrics and gynaecology.

Methods

Participants were interviewed by members of the UK Audit and Research in Obstetrics and Gynaecology trainees' collaborative between 28 March and 7 April 2020. We used a quantitative analysis for closed‐ended questions and a thematic framework analysis for open comments.

Results

We received responses from 148/155 units (95%), most of the participants were in years 3–7 of training (121/148, 82%). Most completed specific training drills for managing obstetric and gynaecological emergencies in women with COVID‐19 (89/148, 60.1%) and two‐person donning and doffing of Personal Protective Equipment (PPE) (96/148, 64.9%). The majority of surveyed units implemented COVID‐19‐specific protocols (130/148, 87.8%), offered adequate PPE (135/148, 91.2%) and operated dedicated COVID‐19 emergency theatres (105/148, 70.8%). Most units reduced face‐to‐face antenatal clinics (117/148, 79.1%) and suspended elective gynaecology services (131/148, 88.5%). The 2‐week referral pathway for oncological gynaecology was not affected in half of the units (76/148, 51.4%), but half reported a planned reduction in oncology surgery (82/148, 55.4%).

Conclusion

The provision of obstetrics and gynaecology services in the UK during the acute phase of the COVID‐19 pandemic seems to be in line with current guidelines, but strategic planning is needed to restore routine gynaecology services and ensure safe access to maternity care in the long term.

Tweetable abstract

Provision of obstetrics and gynaecology services during the acute phase of COVID‐19 is in line with current guidelines, strategic planning is needed to restore routine services and ensure safe access to care in the long term.

Provision of obstetrics and gynaecology services during the acute phase of COVID‐19 is in line with current guidelines, strategic planning is needed to restore routine services and ensure safe access to care in the long term.

This paper includes Author Insights, a video abstract available at https://vimeo.com/rcog/authorinsights16313

Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa

These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients.

Epidemiology and Clinical Outcomes of Hospitalizations for Acute Respiratory or Febrile Illness and Laboratory-Confirmed Influenza Among Pregnant Women During Six Influenza Seasons, 2010-2016

BACKGROUND

Pregnant women are at increased risk of seasonal influenza hospitalizations, but data about the epidemiology of severe influenza among pregnant women remain largely limited to pandemics.

METHODS

To describe the epidemiology of hospitalizations for acute respiratory infection or febrile illness (ARFI) and influenza-associated ARFI among pregnant women, administrative and electronic health record data were analyzed from retrospective cohorts of pregnant women hospitalized with ARFI who had testing for influenza viruses by reverse-transcription polymerase chain reaction (RT-PCR) in Australia, Canada, Israel, and the United States during 2010-2016.

RESULTS

Of 18 048 ARFI-coded hospitalizations, 1064 (6%) included RT-PCR testing for influenza viruses, 614 (58%) of which were influenza positive. Of 614 influenza-positive ARFI hospitalizations, 35% were in women with low socioeconomic status, 20% with underlying conditions, and 67% in their third trimesters. The median length of influenza-positive hospitalizations was 2 days (interquartile range, 1-4), 18% (95% confidence interval [CI], 15%-21%) resulted in delivery, 10% (95% CI, 8%-12%) included a pneumonia diagnosis, 5% (95% CI, 3%-6%) required intensive care, 2% (95% CI, 1%-3%) included a sepsis diagnosis, and <1% (95% CI, 0%-1%) resulted in respiratory failure.

CONCLUSIONS

Our findings characterize seasonal influenza hospitalizations among pregnant women and can inform assessments of the public health and economic impact of seasonal influenza on pregnant women.

Brand-specific enhanced safety surveillance of GSK's Fluarix Tetra seasonal influenza vaccine in England: 2017/2018 season

In compliance with the European Medicine Agency guidance to detect any potential safety concerns associated with influenza vaccination, an enhanced safety surveillance study was conducted in England during the 2017/18 influenza season. The primary objective was to estimate the incidence rates of adverse events occurring within seven days of vaccination with Fluarix Tetra. In nine General Practices, seasonal influenza vaccine was administered to patients according to local guidelines. Events following immunization were collected using customized cards (enhanced component) combined with electronic health records [EHRs] (EHR component) to estimate incidence rates of adverse events experienced post vaccination. The study ran from 01-Sep-2017 to 30-Nov-2017. A total of 23,939 subjects were vaccinated of whom 16,433 received Fluarix Tetra. The cumulative incidence rates of adverse events of interest for Fluarix Tetra were 7.25% [95% CI, 5.95–8.73] for events reported by card alone, and 9.21% [95% CI, 7.37–11.34] when combined with EHR data. The type and frequency of events reported were consistent with the Fluarix Tetra Summary of Product Characteristics. The study supports and confirms the safety profile of Fluarix Tetra.

ClinicalTrials.gov number: NCT03278067

Does the availability of influenza vaccine at prenatal care visits and of immediate vaccination improve vaccination coverage of pregnant women?

Introduction

Although vaccination against influenza is recommended for pregnant women in France because it exposes them to a risk of death and severe respiratory complications, their vaccination coverage in 2016 was estimated at 7%. This study's principal objective was to assess the association between the availability of influenza vaccination at prenatal care visits and vaccination coverage.

Material and methods

This multicenter survey took place in 3 Paris-area public hospital (AP-HP) maternity wards (A, B, and C). Only maternity ward A offered the vaccine and vaccination without charge at prenatal visits. Data were collected from parturients during 10 days in January 2017 by a self-administered anonymous questionnaire.

Results

Data from 248 women showed overall vaccination coverage of 19.4% (48/248): 35.4% (46/130) in maternity unit A, 2.7% (2/75) in B, and 0% (0/43) in C (P<0.01). After adjustment for socio-demographic characteristics, women at maternity ward A were significantly more likely to be vaccinated than those at B and C (aOR 25.52, 95%CI [5.76–113.10]). Other factors significantly associated with higher vaccination coverage were the mother’s French birth (aOR 2.37 CI [1.03–5.46]) and previous influenza vaccination (aOR 3.13, 95%CI [1.25–7.86]). Vaccinated women generally considered they had received adequate information (aOR 4.15 CI [2.10–8.22]), principally from the professional providing their prenatal care. Nonvaccination was attributed to the absence of an offer of vaccination (81.5%), fear of fetal side effects (59.5%), and inadequate information (51.4%).

Conclusion

Our results show that availability of influenza vaccination, free of charge, at prenatal consultations at the maternity ward increases vaccination coverage significantly.

Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa

These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients.

Epidemiology of influenza in pregnant women hospitalized with respiratory illness in Moscow, 2012/2013-2015/2016: a hospital-based active surveillance study

Background

To better understand the impact of seasonal influenza in pregnant women we analyzed data collected during four seasons at a hospital for acute respiratory infection that specializes in treating pregnant women.

Methods

This was a single-center active surveillance study of women 15–44 years of age hospitalized for acute respiratory diseases between 2012/2013 and 2015/2016 in Moscow, Russian Federation. Women had to have been hospitalized within 7 days of the onset of symptoms. Swabs were taken within 48 h of admission, and influenza was detected by reverse transcription-polymerase chain reaction.

Results

During the four seasons, of the 1992 hospitalized women 1748 were pregnant. Laboratory-confirmed influenza was detected more frequently in pregnant women (825/1748; 47.2%) than non-pregnant women (58/244; 23.8%) (OR for influenza = 2.87 [95% CI, 2.10–3.92]; p <  0.001). This pattern was homogenous across seasons (p = 0.112 by test of homogeneity of equal odds). Influenza A(H1N1)pdm09 was the dominant strain in 2012/2013, A(H3N2) in 2013/2014, B/Yamagata lineage and A(H3N2) in 2014/2015, and A(H1N1)pdm09 in 2015/2016. Influenza-positive pregnant admissions went to the hospital sooner than influenza-negative pregnant admissions (p <  0.001). The risk of influenza increased by 2% with each year of age and was higher in women with underlying conditions (OR = 1.52 [95% CI, 1.16 to 1.99]). Pregnant women positive for influenza were homogeneously distributed by trimester (p = 0.37 for homogeneity; p = 0.49 for trend). Frequencies of stillbirth, delivery, preterm delivery, and caesarean delivery did not significantly differ between influenza-positive and influenza-negative hospitalized pregnant women or between subtypes/lineages.

Conclusions

Pregnant women are at increased risk for hospitalization due to influenza irrespective of season, circulating viruses, or trimester.

Electronic supplementary material

The online version of this article (10.1186/s12884-019-2192-z) contains supplementary material, which is available to authorized users.

Outcomes of infants born to women with influenza A(H1N1)pdm09

BACKGROUND

Pregnant women with influenza are more likely to have complications, but information on infant outcomes is limited.

METHODS

Five state/local health departments collected data on outcomes of infants born to pregnant women with 2009 H1N1 influenza reported to the Centers for Disease Control and Prevention from April to December 2009. Collaborating sites linked information on pregnant women with confirmed 2009 H1N1 influenza, many who were severely ill, to their infants' birth certificates. Collaborators also collected birth certificate data from two comparison groups that were matched with H1N1-affected pregnancies on month of conception, sex, and county of residence.

RESULTS

490 pregnant women with influenza, 1,451 women without reported influenza with pregnancies in the same year, and 1,446 pregnant women without reported influenza with prior year pregnancies were included. Women with 2009 H1N1 influenza admitted to an intensive care unit (ICU; n = 64) were more likely to deliver preterm infants (<37 weeks), low birth weight infants, and infants with Apgar scores <=6 at 5 min than women in comparison groups (adjusted relative risk, aRR = 3.9 [2.7, 5.6], aRR = 4.6 [2.9, 7.5], and aRR = 8.7 [3.6, 21.2], for same year comparisons, respectively). Women with influenza who were not hospitalized and hospitalized women not admitted to the ICU did not have significantly elevated risks for adverse infant outcomes.

CONCLUSIONS

Severely ill women with 2009 H1N1 influenza during pregnancy were more likely to have adverse birth outcomes than women without influenza, providing more support for influenza vaccination during pregnancy.

Short-Term Birth Sequelae of the 1918-1920 Influenza Pandemic in the United States: State-Level Analysis

This paper examines short-term birth sequelae of the influenza pandemic of 1918-1920 in the United States using monthly data on births and all-cause deaths for 19 US states in conjunction with data on maternal deaths, stillbirths, and premature births. The data on births and all-cause deaths are adjusted for seasonal and trend effects, and the residual components of the 2 time series coinciding with the timing of peak influenza mortality are examined for these sequelae. Notable findings include: 1) a drop in births in the 3 months following peak mortality; 2) a reversion in births to normal levels occurring 5-7 months after peak mortality; and 3) a steep drop in births occurring 9-10 months after peak mortality. Interpreted in the context of parallel data showing elevated premature births, stillbirths, and maternal mortality during times of peak influenza mortality, these findings suggest that the main impacts of the 1918-1920 influenza on reproduction occurred through: 1) impaired conceptions, possibly due to effects on fertility and behavioral changes; 2) an increase in the preterm delivery rate during the peak of the pandemic; and 3) elevated maternal and fetal mortality, resulting in late-term losses in pregnancy.

Hormonal Regulation of Physiology, Innate Immunity and Antibody Response to H1N1 Influenza Virus Infection During Pregnancy

In 2009, the H1N1 swine flu pandemic highlighted the vulnerability of pregnant women to influenza viral infection. Pregnant women infected with influenza A virus were at increased risk of hospitalization and severe acute respiratory distress syndrome (ARDS), which is associated with high mortality, while their newborns had an increased risk of pre-term birth or low birth weight. Pregnant women have a unique immunological profile modulated by the sex hormones required to maintain pregnancy, namely progesterone and estrogens. The role of these hormones in coordinating maternal immunotolerance in uterine tissue and cellular subsets has been well researched; however, these hormones have wide-ranging effects outside the uterus in modulating the immune response to disease. In this review, we compile research findings in the clinic and in animal models that elaborate on the unique features of H1N1 influenza A viral pathogenesis during pregnancy, the crosstalk between innate immune signaling and hormonal regulation during pregnancy, and the role of pregnancy hormones in modulating cellular responses to influenza A viral infection at mid-gestation. We highlight the ways in which lung architecture and function is stressed by pregnancy, increasing baseline inflammation prior to infection. We demonstrate that infection disrupts progesterone production and upregulates inflammatory mediators, such as cyclooxygenase-2 (COX-2) and prostaglandins, resulting in pre-term labor and spontaneous abortions. Lastly, we profile the ways in which pregnancy alters innate and adaptive cellular immune responses to H1N1 influenza viral infection, and the ways in which these protect fetal development at the expense of effective long-term immune memory. Thus, we highlight advancements in the field of reproductive immunology in response to viral infection and illustrate how that knowledge might be used to develop more effective post-infection therapies and vaccination strategies.

The Relationship Between 2009 Pandemic H1N1 Influenza During Pregnancy and Preterm Birth: A Population-based Cohort Study

BACKGROUND

Previous studies of maternal influenza illness and preterm birth have yielded inconsistent results. Our objective was to assess the association between 2009 pandemic H1N1 (pH1N1) influenza during pregnancy and preterm birth in a large obstetrical population.

METHODS

We linked a province-wide birth registry with health administrative databases to identify influenza-coded hospitalizations, emergency department visits, or physician visits among pregnant women during the 2009 H1N1 pandemic (our proxy for clinical pH1N1 influenza illness). Using Cox regression, we estimated adjusted hazard ratios (aHR) for preterm birth and spontaneous preterm birth treating influenza as a time-varying exposure.

RESULTS

Among 192,082 women with a singleton live birth, 2,925 (1.5%) had an influenza-coded health care encounter during the 2009 H1N1 pandemic. Compared with unexposed pregnancy time, there was no association between exposure to the pandemic, with or without clinical influenza illness, and preterm birth (no pH1N1 diagnosis: aHR = 1.0; 95% confidence interval [CI] = 0.98, 1.1; pH1N1 diagnosis: aHR = 1.0; 95% CI = 0.88, 1.2). Among women with preexisting medical conditions, influenza was associated with increased preterm birth (aHR = 1.5; 95% CI = 1.1, 2.2) and spontaneous preterm birth (aHR = 1.7; 95% CI = 1.1, 2.6), and these associations were strongest in the third trimester and when data were analyzed to allow for a transient acute effect of influenza.

CONCLUSIONS

In the general obstetrical population, there was no association between pH1N1 influenza illness and preterm birth, but women with preexisting medical conditions known to increase the risk of influenza-associated morbidity were at elevated risk.

Infections in Pregnancy

Infections during pregnancy may affect a developing fetus. If left untreated, these infections can lead to the death of the mother, fetus, or neonate and other adverse sequelae. There are many factors that impact infection during pregnancy, such as the immune system changes during pregnancy, hormonal flux, stress, and the microbiome. We review some of the outcomes of infection during pregnancy, such as preterm birth, chorioamnionitis, meningitis, hydrocephaly, developmental delays, microcephaly, and sepsis. Transmission routes are discussed regarding how a pregnant woman may pass her infection to her fetus. This is followed by examples of infection during pregnancy: bacterial, viral, parasitic, and fungal infections. There are many known organisms that are capable of producing similar congenital defects during pregnancy; however, whether these infections share common mechanisms of action is yet to be determined. To protect the health of pregnant women and their offspring, additional research is needed to understand how these intrauterine infections adversely affect pregnancies and/or neonates in order to develop prevention strategies and treatments.

Distinct T and NK cell populations may serve as immune correlates of protection against symptomatic pandemic influenza A(H1N1) virus infection during pregnancy

Maternal influenza infection during pregnancy is associated with increased risk of morbidity and mortality. However, the link between the anti-influenza immune responses and health-related risks during infection is not well understood. We have analyzed memory T and NK cell mediated immunity (CMI) responses in pandemic influenza A(H1N1)pdm09 (pdm09) virus infected non-vaccinated pregnant women participating in the Norwegian Influenza Pregnancy Cohort (NorFlu). The cohort includes information on immunization, self-reported health and disease status, and biological samples (plasma and PBMC). Infected cases (N = 75) were defined by having a serum hemagglutination inhibition (HI) titer > = 20 to influenza pdm09 virus at the time of delivery, while controls (N = 75) were randomly selected among non-infected pregnant women (HI titer <10). In ELISpot assays cases had higher frequencies of IFNγ⁺ CD8⁺ T cells responding to pdm09 virus or conserved CD8 T cell-restricted influenza A virus epitopes, compared to controls. Within this T cell population, frequencies of CD95⁺ late effector (CD45RA⁺CCR7^-) and naive (CD45RA⁺CCR7⁺) CD8⁺ memory T cells correlated inversely with self-reported influenza illness (ILI) symptoms. ILI symptoms in infected women were also associated with lower numbers of poly-functional (IFNγ⁺TNFα⁺, IL2⁺IFNγ⁺, IL2⁺IFNγ⁺TNFα⁺) CD4⁺ T cells and increased frequencies of IFNγ⁺CD3^-CD7⁺ NK cells compared to asymptomatic cases, or controls, after stimulation with the pdm09 virus. Taken together, virus specific and functionally distinct T and NK cell populations may serve as cellular immune correlates of clinical outcomes of pandemic influenza disease in pregnant women. Our results may provide information important for future universal influenza vaccine design.

Evaluation of Health in Pregnancy grants in Scotland: a natural experiment using routine data

Background

Pregnancy and the period around birth are critical for the development and improvement of population health as well as the health of mothers and babies, with outcomes such as birthweight influencing adult health.

Objectives

We evaluated the clinical effectiveness and cost-effectiveness of the Health in Pregnancy (HiP) grants in Scotland, looking for differential outcomes when the scheme was in place, as well as before its implementation and after its withdrawal.

Design

The HiP grants were evaluated as a natural experiment using interrupted time series analysis. We had comparison groups of women who delivered before the grants were introduced and after the grants were withdrawn.

Setting

Scotland, UK.

Participants

A total of 525,400 singleton births delivered between 24 and 44 weeks in hospitals across Scotland between 1 January 2004 and 31 December 2014.

Intervention

The HiP grant was a universal, unconditional cash transfer of £190 for women in Great Britain and Northern Ireland reaching 25 weeks of pregnancy if they had sought health advice from a doctor or midwife. The grant was introduced for women with a due date on or after 6 April 2009 and subsequently withdrawn for women reaching the 25th week of pregnancy on or after 1 January 2011. The programme was paid for by Her Majesty’s Treasury.

Main outcome measures

Our primary outcome measure was birthweight. Secondary outcome measures included maternal behaviour, measures of size, measures of stage and birth outcomes.

Data sources

The data came from the Scottish maternity and neonatal database held by the Information and Services Division at the NHS National Services Scotland.

Results

There was no statistically significant effect on birthweight, with births during the intervention period being, on average, 2.3 g [95% confidence interval (CI) –1.9  to 6.6 g] lighter than would have been expected had the pre-intervention trend continued. Mean gestational age at booking (i.e. the first antenatal appointment with a health-care professional) decreased by 0.35 weeks (95% CI 0.29 to 0.41 weeks) and the odds of booking before 25 weeks increased by 10% [odds ratio (OR) 1.10, 95% CI 1.02 to 1.18] during the intervention but decreased again post intervention (OR 0.91, 95% CI 0.83 to 1.00). The odds of neonatal death increased by 84% (OR 1.84, 95% CI 1.22 to 2.78) and the odds of having an emergency caesarean section increased by 7% (OR 1.07, 95% CI 1.03 to 1.10) during the intervention period.

Conclusions

The decrease in the odds of booking before 25 weeks following withdrawal of the intervention makes it likely that the HiP grants influenced maternal health-care-seeking behaviour. It is unclear why neonatal mortality and emergency caesarean section rates increased, but plausible explanations include the effects of the swine flu outbreak in 2009 and the global financial crisis. The study is limited by its non-randomised design. Future research could assess an eligibility threshold for payment earlier than the 25th week of pregnancy.

Funding

The National Institute for Health Research Public Health Research programme. The Social and Public Health Sciences Unit is core funded by the Medical Research Council (MC_UU_12017/13) and the Scottish Government Chief Scientist Office (SPHSU13).

SOMANZ guidelines for the investigation and management sepsis in pregnancy

SOMANZ (Society of Obstetric Medicine Australia and New Zealand) has written a guideline to provide evidence-based guidance for the investigation and care of women with sepsis in pregnancy or the postpartum period. The guideline is evidence-based and incorporates recent changes in the definition of sepsis. The etiology, investigation and treatment of bacterial, viral and non-infective causes of sepsis are discussed. Obstetric considerations relevant to anaesthetic and intensive care treatment in sepsis are also addressed. A multi-disciplinary group of clinicians with experience in all aspects of the care of pregnant women have contributed to the development of the guidelines. This is an executive summary of the guidelines.

Incidence of influenza virus infection among pregnant women: a systematic review

BACKGROUND

The World Health Organization (WHO) considers pregnant women to be a risk group for severe influenza disease. We conducted a systematic review to evaluate influenza disease incidence in pregnant women in order to inform estimates of influenza vaccine impact for low-resource countries.

METHODS

We performed electronic literature searches, targeting studies on the following outcomes in pregnant women: attack rate, hospitalization rate, intensive care unit admission rate, mortality rate, and disability-adjusted life years lost. Only original studies published in peer-reviewed journals that had laboratory confirmation for influenza virus infection and included population-based incidence rates with denominator data were included. We summarized study characteristics in descriptive tables and outcome-specific Forest plots. We generated summary incidence rates using random effects models and assessed statistical heterogeneity by visual examination of Forest plots, and by χ 2 and I2 tests.

RESULTS

We identified 1543 articles, of which nine articles met the study inclusion criteria. Five were case series, three were cohort studies, and one was a randomized controlled trial. Eight studies were from high-income countries, and one was from an upper middle-income country. Six studies reported results for pandemic influenza, and three reported seasonal influenza. Statistical heterogeneity was high for all outcomes, and methodologies and duration of surveillance varied considerably among studies; therefore, we did not perform meta-analyses.

CONCLUSIONS

Study quality was very low according to GRADE criteria. More data on influenza disease incidence in pregnant women, particularly in low- and middle-income countries and for seasonal influenza disease, are needed to inform public health decision-making.

A Systematic Review and Meta-Analysis of Influenza A Virus Infection During Pregnancy Associated with an Increased Risk for Stillbirth and Low Birth Weight

BACKGROUND/AIMS

Impaired pregnancy outcomes, such as low birth weight are associated with increased disease risk in later life, however little is known about the impact of common infectious diseases during pregnancy on birth weight. The study had two aims: a) to investigate risk factors of influenza virus infection during pregnancy, and b) to analyze the impact of influenza virus infection on pregnancy outcome, especially birth weight.

METHODS

Prospective and retrospective observational studies found in PubMed, MEDLINE, Embase, Google Scholar, and WangFang database were included in this meta analysis. Data of included studies was extracted and analyzed by the RevMan software.

RESULTS

Pregnant women with anemia (P=0.004, RR=1.46, 95% CI: 1.13-1.88), obesity (P<0.00001, RR=1.35, 95% CI: 1.25-1.46) and asthma (P<0.00001, RR=1.99, 95% CI: 1.67-2.37) had higher rates of influenza virus infection. Regarding birth outcomes, influenza A virus infection did not affect the likelihood for cesarean section. Mothers with influenza had a higher rate of stillbirth (P=0.04, RR=2.36, 95% CI: 1.05-5.31), and their offspring had low 5-minute APGR Scores (P=0.009, RR=1.39, 95% CI: 1.08-1.79). Furthermore, the rate for birth weight < 2500g (P=0.04, RR=1.71, 95% CI: 1.03-2.84) was increased.

CONCLUSION

Results of this study showed that anemia, asthma and obesity during pregnancy are risk factors influenza A virus infection during pregnancy. Moreover, gestational influenza A infection impairs pregnancy outcomes and increases the risk for low birth weight, a known risk factor for later life disease susceptibility.

Implementation of the Recommendation to Vaccinate Pregnant Women against Seasonal Influenza - Vaccination Rates and Acceptance

Introduction In Germany vaccination recommendations are revised annually and published by the Standing Committee on Vaccination at the Robert Koch Institute (STIKO). In 2010 the vaccination recommendations were amended to include the proposal that pregnant women in the 2nd trimester of pregnancy and pregnant women with additional underlying disease in the 1st trimester of pregnancy should be vaccinated against seasonal influenza. This paper reports on vaccination rates and the factors influencing them. Method A cross-sectional study was carried out in two level 1 perinatal centers in two different German federal states (Saarland and Rhineland-Palatinate) during the influenza seasons of 2012/2013 and 2013/2014. A total of 253 pregnant women were included in the study. Pregnant women were interviewed using a standardized, pre-tested questionnaire and asked whether they were aware of the recommendation to vaccinate against seasonal influenza and about possible factors which might influence their decision to be vaccinated. In addition, data from their vaccination certificates and pregnancy passports were evaluated. Results Overall, the records of only 19.5 % of the pregnant women showed that they had been vaccinated against influenza in pregnancy. Among the group of pregnant women who had a previous history of vaccinations against influenza the willingness to be vaccinated was high (43.3 %) and this figure was statistically significant. The vaccination rate was even higher (49.9 %) and even more statistically significant among pregnant women whose gynecologist or family physician had recommended that they should be vaccinated. In contrast, only 3.3 % of pregnant women who had not been given the recommendation to vaccinate by their physicians were vaccinated against influenza. Discussion The failure to recommend that pregnant women be vaccinated against influenza and women's lack of any previous experience of influenza vaccination were the main reasons for the inadequate influenza vaccination coverage in pregnancy. Conclusion One of the key points to increase the influenza vaccination rate is to intensify the counselling of the pregnant women through the gynecologist.

Neuraminidase inhibitors during pregnancy and risk of adverse neonatal outcomes and congenital malformations: population based European register study

Objective To evaluate the possible effects of exposure to neuraminidase inhibitors during embryo-fetal life with respect to adverse neonatal outcomes and congenital malformations.Design Population based multinational observational cohort study and meta-analysis.Setting National registers covering information on maternal healthcare, births, and prescriptions in Denmark, Norway, and Sweden and the EFEMERIS database from the Haute-Garonne district in France.Participants All women together with their singleton infants born between 1 January 2008 and 31 December 2010. Only infants born at 154 days of gestation or later were included. Infants were defined as exposed if the women filled a prescription during pregnancy for either of the two neuraminidase inhibitors oseltamivir or zanamivir.Main outcomes Low birth weight, low Apgar score, preterm birth, small for gestational age birth, stillbirth, neonatal mortality, neonatal morbidity, and congenital malformations. Crude and adjusted hazard ratios of preterm birth were estimated using Cox regression models. Crude and adjusted odds ratios for other outcomes were estimated by logistic regression models.Results The study included 5824 (0.8%) exposed women and their infants and 692 232 who were not exposed. Exposure to neuraminidase inhibitors in utero was not associated with increased risks of any of the investigated neonatal outcomes, including low birth weight (adjusted odds ratio 0.77, 95% confidence interval 0.65 to 0.91), low Apgar score (adjusted odds ratio 0.87, 0.67 to 1.14), preterm birth (adjusted hazard ratio 0.97, 0.86 to 1.10), small for gestational age birth (adjusted odds ratio 0.72, 0.59 to 0.87), stillbirth (adjusted odds ratio 0.81, 0.51 to 1.30), neonatal mortality (adjusted odds ratio 1.13, 0.56 to 2.28), and neonatal morbidity (adjusted odds ratio 0.92, 0.86 to 1.00). No increased risk of congenital malformations overall associated with maternal exposure was observed during the first trimester (adjusted odds ratio 1.06, 0.77 to 1.48). Similarly, no significantly increased risks of any of the outcomes were observed in an analysis restricted to oseltamivir alone.Conclusions This large multinational register study found no increased risks of adverse neonatal outcomes or congenital malformations associated with exposure to neuraminidase inhibitors during embryo-fetal life. The results support previously reported findings that the use of neuraminidase inhibitors is not associated with increased risks of adverse fetal or neonatal outcomes.

Maternal influenza and birth outcomes: systematic review of comparative studies

BACKGROUND

Although pregnant women are considered at high risk for severe influenza disease, comparative studies of maternal influenza and birth outcomes have not been comprehensively summarised.

OBJECTIVE

To review comparative studies evaluating maternal influenza disease and birth outcomes.

SEARCH STRATEGY

We searched bibliographic databases from inception to December 2014.

SELECTION CRITERIA

Studies of preterm birth, small-for-gestational-age (SGA) birth or fetal death, comparing women with and without clinical influenza illness or laboratory-confirmed influenza infection during pregnancy.

DATA COLLECTION AND ANALYSIS

Two reviewers independently abstracted data and assessed study quality.

MAIN RESULTS

Heterogeneity across 16 studies reporting preterm birth precluded meta-analysis. In a subgroup of the highest-quality studies, two reported significantly increased preterm birth (risk ratios (RR) from 2.4 to 4.0) following severe 2009 pandemic H1N1 (pH1N1) influenza illness, whereas those assessing mild-to-moderate pH1N1 or seasonal influenza found no association. Five studies of SGA birth showed no discernible patterns with respect to influenza disease severity (pooled odds ratio 1.24; 95% CI 0.96-1.59). Two fetal death studies were of sufficient quality and size to permit meaningful interpretation. Both reported an increased risk of fetal death following maternal pH1N1 disease (RR 1.9 for mild-to-moderate disease and 4.2 for severe disease).

CONCLUSIONS

Comparative studies of preterm birth, SGA birth and fetal death following maternal influenza disease are limited in number and quality. An association between severe pH1N1 disease and preterm birth and fetal death was reported by several studies; however, these limited data do not permit firm conclusions on the magnitude of any association.

TWEETABLE ABSTRACT

Comparative studies are limited in quality but suggest severe pandemic H1N1 influenza increases preterm birth.

Circulating Influenza Virus and Adverse Pregnancy Outcomes: A Time-Series Study

Individual-level epidemiologic studies of pregnancy outcomes after maternal influenza are limited in number and quality and have produced inconsistent results. We used a time-series design to investigate whether fluctuation in influenza virus circulation was associated with short-term variation in population-level rates of preterm birth, stillbirth, and perinatal death in Ontario between 2003 and 2012. Using Poisson regression, we assessed the association between weekly levels of circulating influenza virus and counts of outcomes offset by the number of at-risk gestations during 3 gestational exposure windows. The rate of preterm birth was not associated with circulating influenza level in the week preceding birth (adjusted rate ratio = 1.01, 95% confidence interval: 1.00, 1.02) or in any other exposure window. These findings were robust to alternate specifications of the model and adjustment for potential confounding. Stillbirth and perinatal death rates were similarly not associated with gestational exposure to influenza circulation during late pregnancy. We could not assess mortality outcomes relative to early gestational exposure because of missing dates of conception for many stillbirths. In this time-series study, population-level influenza circulation was not associated with short-term variation in rates of preterm birth, stillbirth, or perinatal death.

Maternal vaccination for the prevention of influenza: current status and hopes for the future

Influenza is an important cause of morbidity and mortality among pregnant women and young infants, and influenza infection during pregnancy has also been associated with adverse obstetric and birth outcomes. There is substantial evidence - from randomized trials and observational studies - that maternal influenza immunization can protect pregnant women and their infants from influenza disease. In addition, there is compelling observational evidence that prevention of influenza in pregnant women can also protect against certain adverse pregnancy outcomes, including stillbirth and preterm birth. In this article we will review and evaluate the literature on both the burden of influenza disease in pregnant women and infants, as well as the multiple potential benefits of maternal influenza immunization for mother, fetus, and infant. We will also review key clinical aspects of maternal influenza immunization, as well as identify remaining knowledge gaps, and discuss avenues for future investigation.

Influenza in the Emergency Department: Vaccination, Diagnosis, and Treatment: Clinical Practice Paper Approved by American Academy of Emergency Medicine Clinical Guidelines Committee

BACKGROUND

Influenza is an acute respiratory virus that results in significant worldwide morbidity and mortality each year. As emergency physicians, we are often the first to encounter patients with seasonal influenza. It is therefore critical that we draw on the most recent and relevant research when we make clinical decisions regarding the diagnosis, treatment, and prophylaxis of this disease.

METHODS

A MEDLINE literature search from August 2009 to August 2015 was performed using the keywords influenza vaccination efficacy AND systematic, influenza AND rapid antigen testing, and Oseltamivir AND systematic, while limiting the search to human studies written in the English language. General review articles and case reports were omitted. Each of the selected articles then underwent a structured review.

RESULTS

We identified 163 articles through our literature search, of which 68 were found to be relevant to our clinical questions. These studies then underwent a rigorous review from which recommendations were given.

CONCLUSIONS

Influenza vaccine efficacy continues to range between 40% and 80%. Vaccination has the potential to decrease disease severity and is recommended for individuals older than 6 months of age. If resources permit, vaccination can be offered to patients presenting to the emergency department. Rapid antigen detection for influenza is a simple bedside test with high specificity, but generally low sensitivity. If a patient presents with a syndrome consistent with influenza and has negative rapid antigen detection, they should either receive a confirmatory reverse transcriptase polymerase chain reaction or be treated as if they have influenza. Treatment with neuraminidase inhibitors can decrease the duration of influenza and is recommended in hospitalized patients, or in those with high risk of complications.

Protection from Severe Influenza Virus Infections in Mice Carrying the Mx1 Influenza Virus Resistance Gene Strongly Depends on Genetic Background

Influenza virus infections represent a serious threat to human health. Both extrinsic and intrinsic factors determine the severity of influenza. The MX dynamin-like GTPase 1 (Mx1) gene has been shown to confer strong resistance to influenza A virus infections in mice. Most laboratory mouse strains, including C57BL/6J, carry nonsense or deletion mutations in Mx1 and thus a nonfunctional allele, whereas wild-derived mouse strains carry a wild-type Mx1 allele. Congenic C57BL/6J (B6-Mx1^r/r) mice expressing a wild-type allele from the A2G mouse strain are highly resistant to influenza A virus infections, to both mono- and polybasic subtypes. Furthermore, in genetic mapping studies, Mx1 was identified as the major locus of resistance to influenza virus infections. Here, we investigated whether the Mx1 protective function is influenced by the genetic background. For this, we generated a congenic mouse strain carrying the A2G wild-type Mx1 resistance allele on a DBA/2J background (D2-Mx1^r/r). Most remarkably, congenic D2-Mx1^r/r mice expressing a functional Mx1 wild-type allele are still highly susceptible to H1N1 virus. However, pretreatment of D2-Mx1^r/r mice with alpha interferon protected them from lethal infections. Our results showed, for the first time, that the presence of an Mx1 wild-type allele from A2G as such does not fully protect mice from lethal influenza A virus infections. These observations are also highly relevant for susceptibility to influenza virus infections in humans.

IMPORTANCE Influenza A virus represents a major health threat to humans. Seasonal influenza epidemics cause high economic loss, morbidity, and deaths each year. Genetic factors of the host strongly influence susceptibility and resistance to virus infections. The Mx1 (MX dynamin-like GTPase 1) gene has been described as a major resistance gene in mice and humans. Most inbred laboratory mouse strains are deficient in Mx1, but congenic B6-Mx1^r/r mice that carry the wild-type Mx1 gene from the A2G mouse strain are highly resistant. Here, we show that, very unexpectedly, congenic D2-Mx1^r/r mice carrying the wild-type Mx1 gene from the A2G strain are not fully protected against lethal influenza virus infections. These observations demonstrate that the genetic background is very important for the protective function of the Mx1 resistance gene. Our results are also highly relevant for understanding genetic susceptibility to influenza virus infections in humans.

Influenza virus infection in pregnancy: a review

BACKGROUND

Influenza virus infection is very common and a significant cause of morbidity and mortality in specific populations like pregnant women. Following the 2009 pandemic, several reports on the effects of influenza virus infection on maternal health and pregnancy outcome have been published. Also the safety and efficacy of antiviral treatment and vaccination of pregnant women have been studied. In this review, we have analyzed and summarized these data.

OBJECTIVE

To provide information on the influence of influenza virus infection during pregnancy on maternal health and pregnancy outcome and on the effect of treatment and vaccination.

DATA SOURCES

We have searched Medline, Embase and the Cochrane Library. We used influenza, influenz*, pregnancy and pregnan* as search terms.

STUDY SELECTION

In total, 294 reports were reviewed and judged according to the STROBE guidelines or CONSORT statement. In all, 100 studies, published between 1961 and 2015, were included.

RESULTS

Compared to the general population, pregnant women are more often hospitalized and admitted to an intensive care unit due to influenza virus infection. For hospitalized patients, increased rates of preterm birth and fetal/neonatal death are reported. Early treatment with oseltamivir is associated with a reduced risk of severe disease. Vaccination of pregnant women is safe and reduces maternal and neonatal morbidity.

CONCLUSIONS

There is level 2b evidence that maternal health and pregnancy outcome can be severely affected by influenza virus infection. Antiviral treatment may diminish these effects and vaccination protects pregnant women and neonates from infection (level of evidence 2b and 1b, respectively).

Knowledge, attitudes, and acceptability about influenza vaccination in Korean women of childbearing age

Objective

The aims of the present study were to investigate the women's perspective on influenza infection and vaccination and to evaluate how they influence vaccine acceptability, in Korean women of childbearing age.

Methods

This was a prospective study by random survey of women of childbearing age (20 to 45 years). They were asked to complete a questionnaire assessing their knowledge, attitudes and acceptability of influenza vaccination before and during pregnancy. This study utilized data from the Korea National Health and Nutrition Examination Survey (KNHANES) between 2008 and 2012, to analyze the recent influenza vaccination trends.

Results

According to KNHANES (2008-2012), influenza vaccination rates in women of childbearing age have increased up to 26.4%, after 2009. The questionnaire was completed by 308 women. Vaccination rate during pregnancy or planning a pregnancy was 38.6%. The immunization rate increased significantly with the mean number of correct answers (P<0.001). Women who received influenza vaccination were more likely to be previously informed of the recommendations concerning the influenza vaccination before or during pregnancy, received the influenza vaccination in the past, and of the opinion that influenza vaccination is not dangerous during pregnancy, with odds ratios of 14.6 (95% confidence interval [CI], 6.44 to 33.33; P<0.0001), 3.6 (95% CI, 1.84 to 6.97; P=0.0002) and 2.7 (95% CI, 1.34 to 5.47; P=0.0057).

Conclusion

Influenza vaccination rate in women of childbearing age has increased in this study and national data. More information and recommendation by healthcare workers, especially obstetricians, including safety of vaccination, might be critical for improving vaccination rate in women of childbearing age.

Planning for a cohort study to investigate the impact and management of influenza in pregnancy in a future pandemic

Background

Evidence from the 2009 A/H1N1 influenza pandemic demonstrated that pregnant women are particularly vulnerable to infection and at an increased risk of death. Active data collection through the UK Obstetric Surveillance System (UKOSS) about women admitted to hospital during the 2009 A/H1N1 pandemic was used to inform ongoing clinical guidance regarding the use of antiviral treatment for pregnant women and demonstrated that, in addition to an increased risk of maternal morbidity, influenza infection in pregnancy is associated with poor perinatal outcomes, including an increased risk of stillbirth and preterm birth. This evidence influenced the decision to offer routine influenza immunisation to pregnant women. Even in a non-epidemic period, pregnant women continue to die from influenza.

Objective

To establish, and then to put into hibernation, the study mechanisms needed to mount a rapid investigation of the impact of pandemic influenza in pregnancy in the event of a newly emerging pandemic strain.

Design

A new UKOSS cohort study was designed, based on the 2009–10 study, and following consultation with the Pandemic Flu Planning Group at the Royal College of Obstetricians and Gynaecologists and the UKOSS Steering Committee, to identify potential previously unanswered questions.

Setting

UK maternity units.

Participants

All pregnant women admitted to hospital with influenza in a future pandemic.

Main outcome measures

Management of pregnant women with influenza infection, intervention rates, treatment and pregnancy outcome for both the mother and fetus.

Results

The study was designed and approved by the UKOSS Steering Committee and then placed into hibernation for activation in the event of an influenza pandemic.

Conclusions

Pregnant women, as a result of their changed immunological status, appear to be particularly susceptible to infection, including from influenza. The existence of the UKOSS enabled us to rapidly mount a study of pregnant women who were hospitalised with 2009 A/H1N1 influenza. Minor modifications to incorporate previously unanswered questions and our previous study enabled us to design, and then put into hibernation, a new study ready to investigate the impact and management of influenza in pregnancy, which is poised for activation in the event of a newly emerging pandemic strain. This will enable real-time data to be available on which to base rapid changes in clinical management as the as-yet-unforeseen pandemic unfolds. In the event of an influenza pandemic the study will be available to be immediately activated following expedited regulatory approvals.

Trial registration

Current Controlled Trials ISRCTN44137563.

Funding

The National Institute for Health Research Health Services and Delivery Research programme.

Optimizing antiviral therapy for influenza: understanding the evidence

Influenza is an important cause of annual epidemics of respiratory viral infection associated with significant morbidity and mortality. Three classes of drugs, the M2 ion channel, neuraminidase and RNA-dependent RNA polymerase inhibitors, are approved for the prevention and treatment of influenza. Due to widespread resistance to the class, the M2 ion channel inhibitors are not recommended currently for therapy. The only polymerase inhibitor, favipiravir, is approved only in Japan and its use is highly restricted. Despite significant data to support the early use of the neuraminidase inhibitors, their use in all patient populations is suboptimal. The data to support the early use of neuraminidase inhibitors will be reviewed, as will current data on the utilization rates in ambulatory and hospitalized populations.

Vaccinations for pregnant women

In the United States, eradication and reduction of vaccine-preventable diseases through immunization has directly increased life expectancy by reducing mortality. Although immunization is a public priority, vaccine coverage among adult Americans is inadequate. The Institute of Medicine, the Community Preventive Services Task Force, and other public health entities have called for the development of innovative programs to incorporate adult vaccination into routine clinical practice. Obstetrician-gynecologists are well suited to serve as vaccinators of women in general and more specifically pregnant women. Pregnant women are at risk for vaccine-preventable disease-related morbidity and mortality and adverse pregnancy outcomes, including congenital anomalies, spontaneous abortion, preterm birth, and low birth weight. In addition to providing direct maternal benefit, vaccination during pregnancy likely provides direct fetal and neonatal benefit through passive immunity (transplacental transfer of maternal vaccine-induced antibodies). This article reviews: 1) types of vaccines; 2) vaccines specifically recommended during pregnancy and postpartum; 3) vaccines recommended during pregnancy and postpartum based on risk factors and special circumstances; 4) vaccines currently under research and development for licensure for maternal-fetal immunization; and 5) barriers to maternal immunization and available patient and health care provider resources.

Pulmonary Disorders in Pregnancy

Pregnancy is associated with some profound changes in the cardiovascular, respiratory, immune, and hematologic systems that impact the clinical presentation of respiratory disorders, their implications in pregnancy, and the decisions to treat. In addition, concerns for fetal well-being and safety of various interventions complicate the management of these disorders. In many circumstances, especially life-threatening ones, decisions are based upon a careful assessment of the risk benefit ratio rather than absolute safety of drugs and interventions. In this chapter, we review some of the common respiratory disorders that internists or obstetricians may be called upon to manage.