Placental Vascular Calcification and Cardiovascular Health: It Is Time to Determine How Much of Maternal and Offspring Health Is Written in Stone

Longitudinal associations between urinary biomarkers of phthalates and replacements with novel in vivo measures of placental health

STUDY QUESTION

What is the longitudinal association between gestational phthalate exposure and in vivo placental outcomes?

SUMMARY ANSWER

Phthalates were adversely associated with placental microvasculature, stiffness, and presence of calcification, with different metabolites associated with different outcomes.

WHAT IS KNOWN ALREADY

Phthalate exposure is ubiquitous and implicated as a contributor to adverse pregnancy outcomes, possibly through impacts on the placenta.

STUDY DESIGN, SIZE, DURATION

A total of 303 women were recruited in early pregnancy and prospectively followed for up to eight visits across gestation in the Human Placenta and Phthalates study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

At each visit, women provided urine samples and underwent placental ultrasounds. Urine was analyzed for 18 metabolites of phthalates and replacements. We took the geometric mean of repeated measurements to reflect pregnancy-averaged phthalate or replacement exposure for each participant (n = 303). Placental microvasculature, stiffness, and microcalcification presence were quantified from ultrasounds at each visit. Higher scores reflected worse placental function for all measures. Generalized linear mixed models were created to estimate the association between pregnancy-averaged exposure biomarker concentrations and repeated outcome measurements for microvasculature and stiffness. Gestational age at the time of calcification detection was modeled using Cox proportional hazards models.

MAIN RESULTS AND THE ROLE OF CHANCE

Monocarboxyisononyl phthalate and summed di(2-ethylhexyl) phthalate metabolites were associated with impaired microvasculature development, such that an interquartile range increase in concentration was associated with 0.11 standard deviation increase in the microvasculature ratio, indicating poorer vascularization (95% CI: 0.00, 0.22); 0.11 [95% CI: -0.01, 0.22], respectively. Monoethyl phthalate was associated with increased placental stiffness (0.09 [95% CI: -0.01, 0.19]) while summed di-iso-butyl phthalate metabolites and monobenzyl phthalate were associated with increased hazard of calcification detection (hazard ratios: 1.18 [95% CI: 0.98, 1.42]; 1.13 [95% CI: 0.96, 1.34]).

LIMITATIONS, REASONS FOR CAUTION

Outcomes used in this study are novel and further investigation is needed to provide clinical context and relevance.

WIDER IMPLICATIONS OF THE FINDINGS

We found evidence of associations between select phthalate biomarkers and various aspects of in vivo placental health, although we did not observe consistency across placental outcomes. These findings could illustrate heterogeneous effects of phthalate exposure on placental function.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported in part by the Intramural Research Program of the NIH, National Institute of Environmental Health Sciences (ZIA ES103344), and NIEHS T32ES007018. The authors declare that they have no competing interests to disclose. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention. Use of trade names is for identification only and does not imply endorsement by the CDC, the Public Health Service, or the US Department of Health and Human Services.

TRIAL REGISTRATION NUMBER

N/A.

Prenatal exposure to particulate matter and infant birth outcomes: Evidence from a population-wide database

There are growing concerns about the impact of pollution on maternal and infant health. Despite an extensive correlational literature, observational studies which adopt methods that seek to address potential biases due to unmeasured confounders draw mixed conclusions. Using a population database of births in Northern Ireland (NI) linked to localized geographic information on pollution in mothers' postcodes (zipcodes) of residence during pregnancy, we examine whether prenatal exposure to PM2.5 is associated with a comprehensive range of birth outcomes, including placental health. Overall, we find little evidence that particulate matter is related to infant outcomes at the pollution levels experienced in NI, once we implement a mother fixed effects approach that accounts for time-invariant factors. This contrasts with strong associations in models that adjust for observed confounders but without fixed effects. While reducing ambient air pollution remains an urgent public health priority globally, our results imply that further improvements in short-run levels of prenatal PM2.5 exposure in a relatively low-pollution, higher-income country context, are unlikely to impact on birth outcomes at the population level.

Possible toxicity of chronic carbon dioxide exposure associated with face mask use, particularly in pregnant women, children and adolescents - A scoping review

Introduction

During the SARS-CoV-2-pandemic, face masks have become one of the most important ubiquitous factors affecting human breathing. It increases the resistance and dead space volume leading to a re-breathing of CO2. So far, this phenomenon and possible implications on early life has not been evaluated in depth.

Method

As part of a scoping review, literature was systematically reviewed regarding CO2 exposure and facemask use.

Results

Fresh air has around 0.04% CO2, while wearing masks more than 5 min bears a possible chronic exposure to carbon dioxide of 1.41% to 3.2% of the inhaled air. Although the buildup is usually within the short-term exposure limits, long-term exceedances and consequences must be considered due to experimental data. US Navy toxicity experts set the exposure limits for submarines carrying a female crew to 0.8% CO2 based on animal studies which indicated an increased risk for stillbirths. Additionally, mammals who were chronically exposed to 0.3% CO2 the experimental data demonstrate a teratogenicity with irreversible neuron damage in the offspring, reduced spatial learning caused by brainstem neuron apoptosis and reduced circulating levels of the insulin-like growth factor-1. With significant impact on three readout parameters (morphological, functional, marker) this chronic 0.3% CO2 exposure has to be defined as being toxic. Additional data exists on the exposure of chronic 0.3% CO2 in adolescent mammals causing neuron destruction, which includes less activity, increased anxiety and impaired learning and memory. There is also data indicating testicular toxicity in adolescents at CO2 inhalation concentrations above 0.5%.

Discussion

There is a possible negative impact risk by imposing extended mask mandates especially for vulnerable subgroups. Circumstantial evidence exists that extended mask use may be related to current observations of stillbirths and to reduced verbal motor and overall cognitive performance in children born during the pandemic. A need exists to reconsider mask mandates.

Histopathological Changes in Placenta of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-Cov-2) Infection and Maternal and Perinatal Outcome in COVID-19

Background

Whether vertical transmission or placental pathology occurs after maternal infection during pregnancy remains unknown. There is a clear need for studies on the impact of COVID-19 on pregnancy outcome. A systemic inflammatory or hypercoagulable state may be the contributing factor for placental pathology.

Methods

The pregnant women with COVID-19 who delivered between May 2020 and May 2021 were followed and data were collected about pregnancy course and placentas were examined for macro- and microscopical changes and were compared to controls with non-infected women.

Results

Placenta of COVID-19-infected females had increased prevalence of decidual arteriopathy and placental injury reflecting hypoxia and uteroplacental insufficiency within the intervillous space. Features of maternal vascular malperfusion such as increased syncytial knots were present in 100% cases. Fibrinoid necrosis was seen in 100% cases and increased focal perivillous fibrin depositions were presented in 37.7% cases. About one fourth infected placentas had evidence of villitis. Even after matching for comorbidities like preeclampsia, these changes were present.

Conclusion

The most common pathological findings of the placenta of COVID-19 infections are signs of maternal and fetal malperfusion. Future studies should target infections in different stage of gestation, including first and second trimesters.

Maternal Underweight and Obesity Are Associated with Placental Pathologies in Human Pregnancy

Maternal underweight and obesity are prevalent conditions, associated with chronic, low-grade inflammation, poor fetal development, and long-term adverse outcomes for the child. The placenta senses and adapts to the pregnancy environment in an effort to support optimal fetal development. However, the mechanisms driving these adaptations, and the resulting placental phenotypes, are poorly understood. We hypothesised that maternal underweight and obesity would be associated with increased prevalence of placental pathologies in term and preterm pregnancies. Data from 12,154 pregnancies were obtained from the Collaborative Perinatal Project, a prospective cohort study conducted from 1959 to 1974. Macro- and microscopic placental pathologies were analysed across maternal prepregnancy body mass index (BMI) to assess differences in the presence of pathologies among underweight, overweight, and obese BMI groups compared to normal weight reference BMI at term and preterm. Placental pathologies were also assessed across fetal sex. Pregnancies complicated by maternal obesity had placentae with increased fetal inflammation at preterm, and increased inflammation of maternal gestational tissues at term. In term pregnancies, increasing maternal BMI associated with increased maternal vascular malperfusion (MVM), odds of an appropriately mature placenta for gestational age, and placental weight, and decreased placental efficiency. Male placentae, independent of maternal BMI, had increased inflammation, MVM, and placental efficiency than female placentae, particularly at term. Maternal underweight and obesity are not inert conditions for the placenta, and the histomorphological changes driven by suboptimal maternal BMI may serve as indicators of adversities experienced in utero and potential predictors of future health trajectories.

The Role of Inorganics in Preeclampsia Assessed by Multiscale Multimodal Characterization of Placentae

Preeclampsia is one of the most dangerous diseases in pregnancy. Because of the hypertensive nature of preeclampsia, placental calcifications are believed to be a predictor for its occurrence, analogous to their role in cardiovascular diseases. However, the prevalence and the relevance of calcifications for the clinical outcome with respect to preeclampsia remains controversial. In addition, the role of other inorganic components present in the placental tissue in the development of preeclampsia has rarely been investigated. In this work, we therefore characterized inorganic constituents in placental tissue in groups of both normotensive and preeclamptic patients (N = 20 each) using a multi-scale and multi-modal approach. Examinations included elemental analysis (metallomics), sonography, computed tomography (CT), histology, scanning electron microscopy, X-ray fluorescence and energy dispersive X-ray spectroscopy. Our data show that tissue contents of several heavy metals (Al, Cd, Ni, Co, Mn, Pb, and As) were elevated whereas the Rb content was decreased in preeclamptic compared to normotensive placentae. However, the median mineral content (Ca, P, Mg, Na, K) was remarkably comparable between the two groups and CT showed lower calcified volumes and fewer crystalline deposits in preeclamptic placentae. Electron microscopy investigations revealed four distinct types of calcifications, all predominantly composed of calcium, phosphorus and oxygen with variable contents of magnesium in tissues of both maternal and fetal origin in both preeclamptic and normotensive placentae. In conclusion our study suggests that heavy metals, combined with other factors, can be associated with the development of preeclampsia, however, with no obvious correlation between calcifications and preeclampsia.

A Review on the Vagus Nerve and Autonomic Nervous System During Fetal Development: Searching for Critical Windows

The autonomic nervous system (ANS) is one of the main biological systems that regulates the body's physiology. Autonomic nervous system regulatory capacity begins before birth as the sympathetic and parasympathetic activity contributes significantly to the fetus' development. In particular, several studies have shown how vagus nerve is involved in many vital processes during fetal, perinatal, and postnatal life: from the regulation of inflammation through the anti-inflammatory cholinergic pathway, which may affect the functioning of each organ, to the production of hormones involved in bioenergetic metabolism. In addition, the vagus nerve has been recognized as the primary afferent pathway capable of transmitting information to the brain from every organ of the body. Therefore, this hypothesis paper aims to review the development of ANS during fetal and perinatal life, focusing particularly on the vagus nerve, to identify possible "critical windows" that could impact its maturation. These "critical windows" could help clinicians know when to monitor fetuses to effectively assess the developmental status of both ANS and specifically the vagus nerve. In addition, this paper will focus on which factors-i.e., fetal characteristics and behaviors, maternal lifestyle and pathologies, placental health and dysfunction, labor, incubator conditions, and drug exposure-may have an impact on the development of the vagus during the above-mentioned "critical window" and how. This analysis could help clinicians and stakeholders define precise guidelines for improving the management of fetuses and newborns, particularly to reduce the potential adverse environmental impacts on ANS development that may lead to persistent long-term consequences. Since the development of ANS and the vagus influence have been shown to be reflected in cardiac variability, this paper will rely in particular on studies using fetal heart rate variability (fHRV) to monitor the continued growth and health of both animal and human fetuses. In fact, fHRV is a non-invasive marker whose changes have been associated with ANS development, vagal modulation, systemic and neurological inflammatory reactions, and even fetal distress during labor.

Effect of embryo stage at transfer on placental histopathology features in singleton live births resulting from fresh embryo transfers

OBJECTIVE

To evaluate the effect of embryo stage at transfer on placental histopathology and perinatal outcome in singleton live births resulting from fresh embryo transfers (ETs).

DESIGN

Retrospective cohort study.

SETTING

Not applicable.

PATIENT(S)

The study population included all live births after fresh ETs during the period from 2009 to 2017.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Primary outcomes included anatomic, inflammatory, vascular malperfusion, and villous maturation placental features. Secondary outcomes included fetal, maternal, and perinatal complications.

RESULT(S)

A total of 677 live births were included in the final analysis and were allocated to the cleavage-stage (n = 252) and blastocyst (n = 425) ET groups. After the adjustment for confounding factors, the blastocyst group was found to be associated with a higher incidence of circummarginate membranes insertion (odds ratio [OR] 1.9, 95% confidence interval [CI] 1.2-3.4), delayed villous maturation (OR 8.5, 95% CI 1.2-69.3), chorangiosis (OR 2.0, 95% CI 1.2-3.8), parenchymal calcifications (OR 10.6, 95% CI 1.4-80.2), and intrapartum nonreassuring fetal heart rate tracing (OR 2.4, 95% CI 1.3-4.5). Compared with cleavage-stage ETs, live births resulting from the blastocysts were associated with a lower incidence of velamentous cord insertion (OR 0.5, 95% CI 0.3-0.9), retroplacental hematoma (OR 0.3, 95% CI 0.1-0.8), subchorionic thrombi (OR 0.3, 95% CI 0.1-0.8), and avascular villi (OR 0.2, 95% CI 0.03-0.7).

CONCLUSION(S)

Live births resulting from fresh cleavage-stage and blastocyst ETs have different placental histopathology features, with a higher rate of intrapartum nonreassuring fetal heart rate tracing in the blastocyst group.

Brain and placental transcriptional responses as a readout of maternal and paternal preconception stress are fetal sex specific

INTRODUCTION

Despite a wealth of epidemiological evidence that cumulative parental lifetime stress experiences prior to conception are determinant of offspring developmental trajectories, there is a lack of insight on how these previous stress experiences are stored and communicated intergenerationally. Preconception experiences may impact offspring development through alterations in transcriptional regulation of the placenta, a major determinant of offspring growth and sex-specific developmental outcomes. We evaluated the lasting influence of maternal and paternal preconception stress (PCS) on the mid-gestation placenta and fetal brain, utilizing their transcriptomes as proximate readouts of intergenerational impact.

METHODS

To assess the combined vs. dominant influence of maternal and paternal preconception environment on sex-specific fetal development, we compared transcriptional outcomes using a breeding scheme of one stressed parent, both stressed parents, or no stressed parents as controls.

RESULTS

Interestingly, offspring sex affected the directionality of transcriptional changes in response to PCS, where male tissues showed a predominant downregulation, and female tissues showed an upregulation. There was also an intriguing effect of parental sex on placental programming where paternal PCS drove more effects in female placentas, while maternal PCS produced more transcriptional changes in male placentas. However, in the fetal brain, maternal PCS produced overall more changes in gene expression than paternal PCS, supporting the idea that the intrauterine environment may have a larger overall influence on the developing brain than it does on shaping the placenta.

DISCUSSION

Preconception experiences drive changes in the placental and the fetal brain transcriptome at a critical developmental timepoint. While not determinant, these altered transcriptional states may underlie sex-biased risk or resilience to stressful experiences later in life.

Correlation of ultrasound placental diameter & thickness with gestational age

BACKGROUND & OBJECTIVES

Estimation of fetal maturity is common in obstetric practice especially when the women do not keep accurate menstrual records. An accurate establishment of expected date of delivery is fundamental to the management of both high risk and normal pregnancies. The objective of this study was to determine the placental diameter (PD), placental thickness (PT) and to establish a correlation between PD, PT and gestational age.

METHODS

This is an observational cross-sectional study that examines by means of ultrasonography the correlation between placental diameter and thickness with gestational age in Enugu, South East, Nigeria.

RESULTS

A total of 400 healthy subjects were recruited in 3rd trimester of pregnancy having fulfilled the inclusion criteria. PD and PT in this study did not correlate with parity. There is a linear increase of gestational age and placental thickness and diameter. These increases heighten between 38th week gestation and 40 weeks' gestation. 205.0±1.4, 43.00±0.0 to 215.0±1.4, 46.00±2.8 respectively.

CONCLUSION

Placental thickness and Placental diameter can be used to predict gestational age. It is therefore advised to use PT & PD in ultrasound obstetric assessment especially when Last menstrual period (LMP) is not clear.

Histopathological lesions and exposure to Plasmodium falciparum infections in the placenta increases the risk of preeclampsia among pregnant women

Preeclampsia (PE) is a placental disorder with different phenotypic presentations. In malaria-endemic regions, high incidence of PE is reported, with debilitating foeto-maternal effects, particularly among primigravid women. However, the relationship between placental pathology and Plasmodium falciparum infection in the placenta with PE is underexplored. Placentas from 134 pregnant women were examined after delivery for pathological lesions and placental malaria (PM). They comprised of 69 women without PE (non-PE group) and 65 women diagnosed with PE (PE group). The presence of placental pathology increased the risk of PE, with particular reference to syncytial knots. Placental malaria was 64 (48.1%) and 21 (15.8%) respectively for active and past infections and these proportions were significantly higher in the PE group compared to the non-PE group. Further multivariate analyses showed placental pathology (adjusted (aOR) 3.0, 95% CI = 1.2-7.5), active PM (aOR 6.7, 95% CI = 2.3-19.1), past PM (aOR 12.4, 95% CI = 3.0-51.0) and primigravidity (aOR 6.6, 95% CI 2.4-18.2) to be associated with PE. Our findings suggest that placental histological changes and PM are independent risk factors for PE particularly in primigravida. These findings might improve the management of PE in malaria-endemic regions.

Nano-analytical characterization of endogenous minerals in healthy placental tissue: mineral distribution, composition and ultrastructure

Despite its crucial role, the placenta is the least understood human organ. Recent clinical studies indicate a direct association between placental calcification and maternal and offspring health. This study reveals distinct characteristics of minerals formed during gestational ageing using cutting-edge nano-analytical characterization and paves the way for investigations focused on the identification of potential markers for disease risks in a clinical setting based on atypical placental mineral fingerprints.

T2* relaxometry to characterize normal placental development over gestation in-vivo at 3T

Background: T2* relaxometry has been identified as a non-invasive way to study the placenta in-vivo with good potential to identify placental insufficiency. Typical interpretation links T2* values to oxygen concentrations. This study aimed to comprehensively assess T2* maps as a marker of placental oxygenation in-vivo. Methods: A multi-echo gradient echo echo planar imaging sequence is used in a cohort of 84 healthy pregnant women. Special emphasis is put on spatial analysis: histogram measures, Histogram Asymmetry Measure (HAM) and lacunarity. Influences of maternal, fetal and placental factors and experimental parameters on the proposed measures are evaluated. Results: T2* maps were obtained from each placenta in less than 30sec. The previously reported decreasing trend in mean T2* with gestation was confirmed (3.45 ms decline per week). Factors such as maternal age, BMI, fetal sex, parity, mode of delivery and placental location were shown to be uncorrelated with T2* once corrected for gestational age. Robustness of the obtained values with regard to variation in segmentation and voxel-size were established. The proposed spatially resolved measures reveal a change in T2* in late gestation. Conclusions: T2* mapping is a robust and quick technique allowing quantification of both whole volume and spatial quantification largely independent of confounding factors.

Safety and efficacy of ChAdOx1 RVF vaccine against Rift Valley fever in pregnant sheep and goats

Rift Valley fever virus (RVFV) is a zoonotic mosquito-borne virus that was first discovered in Kenya in 1930 and has since spread to become endemic in much of Africa and the Arabian Peninsula. Rift Valley fever (RVF) causes recurrent outbreaks of febrile illness associated with high levels of mortality and poor outcomes during pregnancy-including foetal malformations, spontaneous abortion and stillbirths-in livestock, and associated with miscarriage in humans. No vaccines are available for human use and those licensed for veterinary use have potential drawbacks, including residual virulence that may contraindicate their use in pregnancy. To address this gap, we previously developed a simian adenovirus vectored vaccine, ChAdOx1 RVF, that encodes RVFV envelope glycoproteins. ChAdOx1 RVF is fully protective against RVF in non-pregnant livestock and is also under development for human use. Here, we now demonstrate that when administered to pregnant sheep and goats, ChAdOx1 RVF is safe, elicits high titre RVFV neutralizing antibody, and provides protection against viraemia and foetal loss, although this protection is not as robust for the goats. In addition, we provide a description of RVFV challenge in pregnant goats and contrast this to the pathology observed in pregnant sheep. Together, our data further support the ongoing development of ChAdOx1 RVF vaccine for use in livestock and humans.