Paradoxical long-term impact of maternal influenza infection on neonates and infants

Transplacental Transmission of SARS-CoV-2: A Narrative Review

Background and Objectives: The study aims to explore the potential for transplacental transmission of SARS-CoV-2, focusing on its pathophysiology, placental defense mechanisms, and the clinical implications for maternal and neonatal health. Materials and Methods: A comprehensive review of the current literature was conducted, analyzing studies on SARS-CoV-2 infection in pregnancy, the expression of key viral receptors (ACE2 and TMPRSS2) in placental cells, and the immune responses involved in placental defense. The review also examined the clinical outcomes related to maternal and neonatal health, including adverse pregnancy outcomes and neonatal infection. Results: The expression of ACE2 and TMPRSS2 in the placenta supports the biological plausibility of SARS-CoV-2 transplacental transmission. Histopathological findings from the infected placentas reveal inflammation, vascular changes, and the evidence of viral particles in placental tissues. Clinical reports indicate an increased risk of preterm birth, intrauterine growth restriction, and neonatal infection in pregnancies affected by COVID-19. However, the frequency and mechanisms of vertical transmission remain variable across studies, highlighting the need for standardized research protocols. Conclusions: SARS-CoV-2 can potentially infect placental cells, leading to adverse pregnancy outcomes and neonatal infection. While evidence of transplacental transmission has been documented, the risk and mechanisms are not fully understood. Ongoing research is essential to clarify these aspects and inform obstetric care practices to improve maternal and neonatal outcomes during the COVID-19 pandemic.

Pathogenesis of viral infections during pregnancy

SUMMARYViral infections during pregnancy are associated with significant adverse perinatal and fetal outcomes. Pregnancy is a unique immunologic and physiologic state, which can influence control of virus replication, severity of disease, and vertical transmission. The placenta is the organ of the maternal-fetal interface and provides defense against microbial infection while supporting the semi-allogeneic fetus via tolerogenic immune responses. Some viruses, such as cytomegalovirus, Zika virus, and rubella virus, can breach these defenses, directly infecting the fetus and having long-lasting consequences. Even without direct placental infection, other viruses, including respiratory viruses like influenza viruses and severe acute respiratory syndrome coronavirus 2, still cause placental damage and inflammation. Concentrations of progesterone and estrogens rise during pregnancy and contribute to immunological adaptations, placentation, and placental development and play a pivotal role in creating a tolerogenic environment at the maternal-fetal interface. Animal models, including mice, nonhuman primates, rabbits, and guinea pigs, are instrumental for mechanistic insights into the pathogenesis of viral infections during pregnancy and identification of targetable treatments to improve health outcomes of pregnant individuals and offspring.

Offspring cardiometabolic outcomes and postnatal growth trajectories after exposure to maternal SARS-CoV-2 infection

OBJECTIVE

The objective of this study is to determine whether in utero exposure to SARS-CoV-2 is associated with increased risk for a cardiometabolic diagnosis by 18 months of age.

METHODS

This retrospective electronic health record (EHR)-based cohort study included the live-born offspring of all individuals who delivered during the COVID-19 pandemic (April 1, 2020-December 31, 2021) at eight hospitals in Massachusetts. Offspring exposure was defined as a positive maternal SARS-CoV-2 polymerase chain reaction test during pregnancy. The primary outcome was presence of an ICD-10 code for a cardiometabolic disorder in offspring EHR by 18 months. Weight-, length-, and BMI-for-age z scores were calculated and compared at 6-month intervals from birth to 18 months.

RESULTS

A total of 29,510 offspring (1599 exposed and 27,911 unexposed) were included. By 18 months, 6.7% of exposed and 4.4% of unexposed offspring had received a cardiometabolic diagnosis (crude odds ratio [OR] 1.47 [95% CI: 1.10 to 1.94], p = 0.007; adjusted OR 1.38 [1.06 to 1.77], p = 0.01). Exposed offspring had a significantly greater mean BMI-for-age z score versus unexposed offspring at 6 months (z score difference 0.19 [95% CI: 0.10 to 0.29], p < 0.001; adjusted difference 0.04 [-0.06 to 0.13], p = 0.4).

CONCLUSIONS

Exposure to maternal SARS-CoV-2 infection was associated with an increased risk of receiving a cardiometabolic diagnosis by 18 months preceded by greater BMI-for-age at 6 months.

Suppression of progesterone by influenza A virus mediates adverse maternal and fetal outcomes in mice

Influenza A virus infection during pregnancy can cause adverse maternal and fetal outcomes but the mechanism responsible remains elusive. Infection of outbred mice with 2009 H1N1 at embryonic day (E) 10 resulted in significant maternal morbidity, placental tissue damage and inflammation, fetal growth restriction, and developmental delays that lasted through weaning. Restriction of pulmonary virus replication was not inhibited during pregnancy, but infected dams had suppressed circulating and placental progesterone (P4) concentrations that were caused by H1N1-induced upregulation of pulmonary cyclooxygenase (COX)-1-, but not COX-2-, dependent synthesis and secretion of prostaglandin (PG) F2α. Treatment with 17-α-hydroxyprogesterone caproate (17-OHPC), a synthetic progestin that is safe to use in pregnancy, ameliorated the adverse maternal and fetal outcomes from H1N1 infection and prevented placental cell death and inflammation. These findings highlight the therapeutic potential of progestin treatments for influenza during pregnancy.IMPORTANCEPregnant individuals are at risk of severe outcomes from both seasonal and pandemic influenza A viruses. Influenza infection during pregnancy is associated with adverse fetal outcomes at birth and adverse consequences for offspring into adulthood. When outbred dams, with semi-allogenic fetuses, were infected with 2009 H1N1, in addition to pulmonary virus replication, lung damage, and inflammation, the placenta showed evidence of transient cell death and inflammation that was mediated by increased activity along the arachidonic acid pathway leading to suppression of circulating progesterone. Placental damage and suppressed progesterone were associated with detrimental effects on perinatal growth and developmental delays in offspring. Treatment of H1N1-infected pregnant mice with 17-OHPC, a synthetic progestin treatment that is safe to use in pregnancy, prevented placental damage and inflammation and adverse fetal outcomes. This novel therapeutic option for the treatment of influenza during pregnancy should be explored clinically.

Suppression of progesterone by influenza A virus mediates adverse maternal and fetal outcomes in mice

Influenza A virus infection during pregnancy can cause adverse maternal and fetal outcomes, but the mechanism responsible remains elusive. Infection of outbred mice with 2009 H1N1 at embryonic day (E) 10 resulted in significant maternal morbidity, placental tissue damage and inflammation, fetal growth restriction, and developmental delays that lasted through weaning. Restriction of pulmonary virus replication was not inhibited during pregnancy, but infected dams had suppressed circulating and placental progesterone (P4) concentrations that were caused by H1N1-induced upregulation of pulmonary cyclooxygenase (COX)-1, but not COX-2-, dependent synthesis and secretion of prostaglandin (PG) F2α. Treatment with 17-α-hydroxyprogesterone caproate (17-OHPC), a synthetic progestin that is safe to use in pregnancy, ameliorated the adverse maternal and fetal outcomes from H1N1 infection and prevented placental cell death and inflammation. These findings highlight the therapeutic potential of progestin treatments for influenza during pregnancy.

Accelerated Longitudinal Weight Gain Among Infants With In Utero COVID-19 Exposure

CONTEXT

Since the initial outbreak of coronavirus disease 2019 (COVID-19), a novel population of children with in utero exposure to maternal infection has emerged whose health outcomes are largely unknown.

OBJECTIVE

To compare longitudinal growth trajectories among infants with vs without in utero COVID-19 exposure.

METHODS

We conducted a longitudinal cohort study leveraging a prospectively enrolled perinatal biorepository among 149 infants with in utero COVID-19 exposure and 127 unexposed controls. Weight, length, and body mass index (BMI) were abstracted from health records at 0, 2, 6, and 12 months and standardized using World Health Organization growth charts. Analyses were adjusted for maternal age, ethnicity, parity, insurance, and BMI as well as infant sex, birthdate, and breastfeeding.

RESULTS

Infants with in utero COVID-19 exposure vs controls exhibited differential trajectories of weight and BMI, but not length, z-score over the first year of life (study group × time interaction, P < .0001 for weight and BMI). Infants born to mothers with prenatal COVID-19 had lower BMI z-score at birth (effect size: -0.35, 95% CI -0.66 to -0.03) and greater gain in BMI z-score from birth to 12 months (effect size: 0.53, 95% CI 0.06 to 0.99). Birth weight z-score mediated a significant proportion of the relationship between COVID-19 exposure and postnatal growth (estimate ± SE, 32 ± 14%, P = .02).

CONCLUSION

Infants with in utero COVID-19 exposure exhibited lower birth weight and accelerated weight gain in the first year of life, which may be harbingers of downstream cardiometabolic pathology. Further studies are needed to delineate cardiometabolic sequelae among this emerging global population.

Randomised controlled trials of behavioural nudges delivered through text messages to increase influenza and COVID-19 vaccines among pregnant women (the EPIC study): study protocol

BACKGROUND

Influenza and COVID-19 infections during pregnancy may have serious adverse consequences for women as well as their infants. However, uptake of influenza and COVID-19 vaccines during pregnancy remains suboptimal. This study aims to assess the effectiveness of a multi-component nudge intervention to improve influenza and COVID-19 vaccine uptake among pregnant women.

METHODS

Pregnant women who receive antenatal care at five tertiary hospitals in South Australia, Western Australia and Victoria will be recruited to two separate randomised controlled trials (RCTs). Women will be eligible for the COVID-19 RCT is they have received two or less doses of a COVID-19 vaccine. Women will be eligible for the influenza RCT if they have not received the 2023 seasonal influenza vaccine. Vaccination status at all stages of the trial will be confirmed by the Australian Immunisation Register (AIR). Participants will be randomised (1:1) to standard care or intervention group (n = 1038 for each RCT). The nudge intervention in each RCT will comprise three SMS text message reminders with links to short educational videos from obstetricians, pregnant women and midwives and vaccine safety information. The primary outcome is at least one dose of a COVID-19 or influenza vaccine during pregnancy, as applicable. Logistic regression will compare the proportion vaccinated between groups. The effect of treatment will be described using odds ratio with a 95% CI.

DISCUSSION

Behavioural nudges that facilitate individual choices within a complex context have been successfully used in other disciplines to stir preferred behaviour towards better health choices. If our text-based nudges prove to be successful in improving influenza and COVID-19 vaccine uptake among pregnant women, they can easily be implemented at a national level.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT05613751. Registered on November 14, 2022.

Maternal mental health concerns during the COVID-19 pandemic in Iran: a content analysis study

BACKGROUND

As crises occur, attention to physical health usually becomes more than mental health, neglecting mental health, especially in some vulnerable groups such as pregnant women and new mothers, can have adverse consequences. Therefore, it is imperative to recognize and comprehend their mental health needs, particularly during critical situations such as the recent COVID-19 pandemic. The aim of this study was to explain the understanding and experience of mental health concerns faced by pregnant and postpartum women during this pandemic.

METHODS

This qualitative study was conducted from March 2021 to November 2021 in Iran. Data were collected using semi-structured in-depth interviews to understand mental health concerns in pregnancy and the postpartum period during the COVID-19 pandemic. Twenty-five purposefully retrieved and participated in the study. Due to the prevalence of coronavirus, most of the participants preferred tele interviews. When data saturation was achieved, the data were codified manually and analyzed using Graneheim and Lundman's approach 2004.

RESULTS

Based on the content analysis of the interviews, 2 main themes, 8 categories 23 subcategories were identified. The identified themes were as follows: (1) Maternal mental health threats and (2) Inadequate access to the required information.

CONCLUSION

The results of this study showed that the main concern and fear of pregnant and postpartum women in the COVID-19 pandemic was the fear of the possibility of death for themselves and/or their fetus/infant. The knowledge that was obtained from the understanding of pregnant women and new mothers about the mental health concerns during the COVID-19 pandemic can help managers in planning to improve and promote women's mental health, especially in critical situations.

Maternal plasma and salivary anelloviruses in pregnancy and preterm birth

Introduction

Human anelloviruses, including torque teno virus (TTV) and torque teno mini virus (TTMV), are ubiquitous in the general population and have no known pathogenicity. We investigated the prevalence and viral load of TTV and TTMV in plasma and saliva over pregnancy, and assessed their association with spontaneous or medically indicated preterm birth.

Methods

This is a secondary analysis of the Measurement of Maternal Stress (MOMS) study, which recruited 744 individuals with singleton pregnancies from 4 US sites (Chicago, Pittsburgh, San Antonio, and rural Pennsylvania). Baseline outpatient visits took place in the second trimester (between 12'0 and 20'6/7  weeks' gestation), and follow-up visits in the third trimester (between 32'0 and 35'6/7  weeks' gestation). In a case-control study design, participants who delivered preterm (<37 weeks) resulting from spontaneous labor and/or preterm premature rupture of membranes ("sPTB") were compared with participants experiencing medically indicated preterm birth ("iPTB"), or delivery at term ("controls"). Plasma and saliva samples obtained during the second and third trimesters were tested for the presence and quantity of TTV and TTMV using real-time PCR. Demographic data were obtained via self-report, and clinical data via medical record review by trained research personnel.

Results

TTV was detected in plasma from 81% (second trimester) and 77% (third trimester) of participants, and in saliva from 64 and 60%. Corresponding detection rates for TTMV were 59 and 41% in plasma, and 35 and 24% in saliva. TTV and TTMV concentrations were similar between matched plasma and saliva samples. TTV prevalence and concentrations were not significantly different between groups (sPTB, iPTB, and controls). However, plasma TTMV in the third trimester was associated with sPTB and earlier gestational age at delivery. The iPTB group was not different from either the sPTB or the control group. In saliva, concentrations of TTV and TTMV were similar among the three groups. Both TTV and TTMV were more prevalent with increasing parity and were more common in Black and Hispanic participants compared to non-Hispanic White participants.

Conclusion

Anellovirus presence (specifically, TTMV) in the third trimester may be associated with preterm birth. Whether this association is causative remains to be determined.

Safety and Protective Effects of Influenza Vaccination in Pregnant Women on Pregnancy and Birth Outcomes in Pune, India: A Cross-Sectional Study

BACKGROUND

Maternal influenza vaccination provides effective protection against influenza infections in pregnant women and their newborns. In India, the influenza vaccine has not yet been offered through immunization programs, owing to the lack of sufficient safety data for pregnant Indian women.

METHODS

This cross-sectional observational study enrolled 558 women admitted to the obstetrics ward of a civic hospital in Pune. Study-related information was obtained from the participants through hospital records and interviews using structured questionnaires. Univariate and multivariable analysis was used, and the chi-square test with adjusted odds ratio was estimated to account for vaccine exposure and the temporal nature of each outcome, respectively.

RESULTS

Women not vaccinated against influenza during pregnancy had a higher risk of delivering very LBW infants, and possible protective effects were suggested (AOR 2.29, 95% CI 1.03 to 5.58, p = 0.03). No association was observed between maternal influenza vaccination for Caesarean section (LSCS) (AOR 0.97, 95% CI, 0.78, 1.85), stillbirth (AOR 1.8, 95% CI 0.18, 24.64) and NICU admission (AOR, 0.87, 0.29 to 2.85), and congenital anomaly (AOR, 0.81, 0.10 to 3.87).

INTERPRETATION

These results show that the influenza vaccine administered during pregnancy is safe and might lower the risk of negative birth outcomes.

Developmental screening of full-term infants at 16 to 18 months of age after in-utero exposure to maternal SARS-CoV-2 infection

OBJECTIVE

To screen for neurodevelopmental delays in a cohort of full-term infants born to mothers with SARS-CoV-2.

STUDY DESIGN

This was a prospective, descriptive cohort study of full-term infants born to mothers with SARS-CoV-2 during pregnancy. Subjects underwent neurodevelopmental screening using the Ages and Stages Questionnaires^®-Third Edition (ASQ^®-3) at 16 to 18 months age.

RESULTS

Of 51 subjects, twelve (24%) were below cutoff, and twenty-seven (53%) were either below or close to the cutoff in at least one developmental domain. Communication (29%), fine motor (31%), and problem-solving (24%) were the most affected domains. There were no differences in outcomes between infants born to asymptomatic and mildly symptomatic mothers.

CONCLUSION

We observed increased risk of neurodevelopmental delays during screening of infants born at full-term to mothers with SARS-CoV-2 at 16 to 18 months age. These results highlight the urgent need for follow-up studies of infants born to mothers with SARS-CoV-2.

Knowledge and Attitudes of Healthcare Professionals Regarding Perinatal Influenza Vaccination during the COVID-19 Pandemic

Immunizations during pregnancy are an important aspect of perinatal care. Although the influenza vaccine during pregnancy is safe, vaccination rates are low. According to research data, one of the reasons for the low vaccination rates among pregnant women is that they do not receive a clear recommendation from healthcare providers. This study aims to record the knowledge and attitudes about influenza vaccination and investigate healthcare professionals' recommendations during the perinatal period. A cross-sectional study was conducted with convenience sampling in Athens, Greece. Our purposive sample included 240 midwives, Ob/Gs, and pediatricians. Data were collected using an appropriate standardized questionnaire with information about demographics, attitudes towards influenza vaccination, and knowledge about the influenza virus and peripartum vaccination. Statistical analysis was conducted using IBM SPSS-Statistics version 26.0. This study identifies the reasons for the lack of vaccine uptake including a wide range of misconceptions or lack of knowledge about influenza infection, lack of convenient access to get vaccinated, etc. Misconceptions about influenza and influenza vaccines could be improved by better education of healthcare workers. Continuing professional education for health professionals is necessary to improve the level of knowledge, prevent negative beliefs, and promote preventive and therapeutic practices.

Biological Sex and Pregnancy Affect Influenza Pathogenesis and Vaccination

Males and females differ in the outcome of influenza A virus (IAV) infections, which depends significantly on age. During seasonal influenza epidemics, young children (< 5 years of age) and aged adults (65+ years of age) are at greatest risk for severe disease, and among these age groups, males tend to suffer a worse outcome from IAV infection than females. Following infection with pandemic strains of IAVs, females of reproductive ages (i.e., 15-49 years of age) experience a worse outcome than their male counterparts. Although females of reproductive ages experience worse outcomes from IAV infection, females typically have greater immune responses to influenza vaccination as compared with males. Among females of reproductive ages, pregnancy is one factor linked to an increased risk of severe outcome of influenza. Small animal models of influenza virus infection and vaccination illustrate that immune responses and repair of damaged tissue following IAV infection also differ between the sexes and impact the outcome of infection. There is growing evidence that sex steroid hormones, including estrogens, progesterone, and testosterone, directly impact immune responses during IAV infection and vaccination. Greater consideration of the combined effects of sex and age as biological variables in epidemiological, clinical, and animal studies of influenza pathogenesis is needed.

Immune Responses to SARS-CoV-2 in Pregnancy: Implications for the Health of the Next Generation

Widespread SARS-CoV-2 infection among pregnant individuals has led to a generation of fetuses exposed in utero, but the long-term impact of such exposure remains unknown. Although fetal infection is rare, children born to mothers with SARS-CoV-2 infection may be at increased risk for adverse neurodevelopmental and cardiometabolic outcomes. Fetal programming effects are likely to be mediated at least in part by maternal immune activation. In this review, we discuss recent evidence regarding the effects of prenatal SARS-CoV-2 infection on the maternal, placental, and fetal immune response, as well as the implications for the long-term health of offspring. Extrapolating from what is known about the impact of maternal immune activation in other contexts (e.g., obesity, HIV, influenza), we review the potential for neurodevelopmental and cardiometabolic morbidity in offspring. Based on available data suggesting potential increased neurodevelopmental risk, we highlight the importance of establishing large cohorts to monitor offspring born to SARS-CoV-2-positive mothers for neurodevelopmental and cardiometabolic sequelae.

Neuropsychiatric outcomes in offspring after fetal exposure to maternal influenza infection during pregnancy: A systematic review

Increasing evidence suggests that influenza infection in pregnancy may disrupt fetal neurodevelopment. The impact of maternal influenza infection on offspring neuropsychiatric health has not been comprehensively reviewed. We systematically reviewed comparative studies evaluating associations between maternal influenza infection and neuropsychiatric health outcomes in offspring. We searched MEDLINE, EMBASE, CINAHL, and Web of Science for articles published until January 7, 2022. Included were English studies evaluating neuropsychiatric outcomes in offspring aged > 6 months born to women with and without influenza during pregnancy, defined as clinical or laboratory-confirmed influenza illness, or being pregnant during pandemics/epidemics. Of 12,010 records screened, 42 studies were included. Heterogeneity in study design, exposures, and outcome definitions precluded meta-analyses. Four of 14 studies assessing schizophrenia reported adjusted ratio estimates from 0.5 to 8.2; most 95% CIs contained the null value; study quality was high in three of four. Two studies reported an increased risk of schizophrenia with influenza exposure any time during pregnancy (adjusted incidence rate ratio 8.2, 95% CI: 1.4-48.8; adjusted odds ratio 1.3, 95% CI: 1.2-1.5); another reported a reduced risk with first-trimester exposure (adjusted risk ratio 0.5, 95% CI: 0.3-0.9). Seven studies of autism spectrum disorder reported adjusted ratio estimates from 0.9 to 4.0; all 95% CIs included the null value; study quality was high in four. No conclusions could be drawn about the association between exposure to maternal influenza and neuropsychiatric outcomes due to the limited quantity and quality of available research. Large observational studies with long-term follow-up are required to investigate these associations.

Obstetric risk in pregnancy interacts with hair cortisone levels to reduce gestational length

Background

Maternal psychological stress has been linked to preterm birth. However, the differential contribution of psychological stress versus stress hormones is not clear. Studies focus primarily on perceived stress and cortisol, with few assessing its inter-convertible hormone cortisone. Furthermore, little is known about the potential moderating roles of obstetric risk and fetal sex in the relationship between maternal stress and gestational length. This gap in knowledge is particularly evident for rural women who typically experience chronic multiple stressors during pregnancy. We explored the relationship of hormonal and psychological stress to gestational length and the effects of obstetric risks and fetal sex on this relationship among Kenyan pregnant women.

Methods

The sample included 130 women recruited between 22 to 28 weeks gestation. They completed a clinical and sociodemographic questionnaire together with the Perceived Stress Scale and provided a hair sample for cortisol and cortisone assay. Women underwent an ultrasound to assess weeks of gestation. At delivery, their pregnancy-related health problems were identified using information extracted from medical records to compile each woman's number of pregnancy risks on the Obstetric Medical Risk Index (OMRI).

Results

Perceived stress and hair cortisol were not significant predictors of gestational length. However, a greater number of obstetric risks on the OMRI was associated with shorter gestational length. This effect was further explained by the interaction between obstetric risk and hair cortisone (B = 0.709, p = 0.02). Hair cortisone levels of mothers who had a shorter gestation were significantly higher in mothers with 2 or more risks on the OMRI but not among mothers with only one or no risks (t = 2.39, p = 0.02). Fetal sex had no relationship to gestational length and also had no moderating effect on the relationship between any stress-related metric and gestational length.

Conclusion

Cortisone levels may increase in anticipation of shorter gestation as a compensatory response to increased obstetric risk. Elevated cortisone may be a more sensitive marker of risk for early delivery than cortisol or psychological stress, with salience for both the male and female fetus.

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.

Changes in amino acid profile of cord blood plasma and amniotic fluid of mothers with COVID-19

Neonates born to mothers with COVID-19 are at risk for infection, they may have high risk of complications during the neonatal period, and long-term health consequences. The study was aimed to define the amino acid profile of blood plasma and amniotic fluid in patients with COVID-19 in order to assess the relationship between the COVID-19 infection during the antenatal period, and metabolomic alterations in the “intrauterine” patient. The levels of 31 amino acids in the samples of amniotic fluid and cord blood plasma of pregnant women with COVID-19, obtained during delivery, were assessed by high-performance liquid chromatography-mass spectrometry. The index group included 29 patients with confirmed diagnosis of COVID-19, and the control group included 17 healthy women with uncomplicated pregnancies. There were significant (p < 0.05) differences in the concentrations of eight amino acids between the studied groups. Logistic regression models were developed (sensitivity 0.84; specificity 1) making it possible to define, whether the assessed amniotic fluid was obtained from COVID-19 patients. Significant differences in the concentrations of four amino acids were observed in the umbilical cord blood. The models developed made it possible to define whether the studied cord blood plasma belonged to controls or to COVID-19 patients (sensitivity and specificity 1). Three amino acids were detected, and their levels were significantly different in COVID-19 patients simultaneously in two points (amniotic fluid and cord blood plasma), depicting the fetal metabolome in a holistic manner. The impact of the virus on those infected results in pronounced metabolomic alterations in the amniotic fluid and the fetal cord blood plasma, which may lead to impaired programming of protein production, but never show up at birth.

The effect of influenza virus infection on pregnancy outcomes: A systematic review and meta-analysis of cohort studies

BACKGROUND

Adverse pregnancy outcomes are risk factors for neonatal mortality and morbidity. While some studies have demonstrated notable associations between influenza and adverse pregnancy outcomes, the findings have contrasted with other studies. This meta-analysis was conducted to assess the effect of influenza infection on pregnancy outcomes.

METHODS

We searched PubMed, Embase, Cochrane Library and Web of Science from inception to 4 November 2020. Relative risks (RRs) with 95% confidence intervals (CIs) were pooled using random-effects or fixed-effects models.

RESULTS

A total of 17 studies involving 2,351,204 participants were included. Influenza infection increased the risk of stillbirth (RR = 3.62, 95% CI: 1.60-8.20), with no significant effect on preterm birth (RR = 1.17, 95%CI: 0.95-1.45), fetal death (RR = 0.93, 95%CI: 0.73-1.18), small for gestational age (SGA) (RR = 1.10, 95%CI: 0.98-1.24) and low birth weight (LBW) (RR = 1.88, 95%CI: 0.46-7.66). In a subgroup analysis of LBW, the association was evident in studies conducted during the 2009 H1N1 pandemic (RR = 2.28, 95%CI: 1.81-2.87), with no evidence of an association in pre-pandemic or post-pandemic studies.

CONCLUSIONS

Influenza virus infection was associated with an increased risk of stillbirth, but its effect on preterm birth, fetal death, SGA and LBW is still uncertain.

Maternal immune responses and obstetrical outcomes of pregnant women with COVID-19 and possible health risks of offspring

Coronavirus disease 2019 (COVID-19) pandemic has spread rapidly across the world. The vast majority of patients with COVID-19 manifest mild to moderate symptoms but may progress to severe cases or even mortalities. Young adults of reproductive age are the most affected population by SARS-CoV-2 infection. However, there is no consensus yet if pregnancy contributes to the severity of COVID-19. Initial studies of pregnant women have found that COVID-19 significantly increases the risk of preterm birth, intrauterine growth restriction, and low birth weight, which have been associated with non-communicable diseases in offspring. Besides, maternal viral infections with or without vertical transmission have been allied with neurological and behavioral disorders of the offspring. In this review, obstetrical outcomes of women with COVID-19 and possible risks for their offspring are discussed by reviewing maternal immune responses to COVID-19 based on the current evidence. Structural and systemic follow-up of offspring who are exposed to SARS-CoV-2 in-utero is suggested.