Placental Adaptation: What Can We Learn from Birthweight:Placental Weight Ratio?

Swimming Program on Mildly Diabetic Rats in Pregnancy

The present study aims to confirm if the moderate-intensity swimming has successful glycemic control and non-toxic oxidative stress levels and to verify the influence on pancreatic adaptations, embryo implantation, and placental efficiency. Female Wistar rats were randomly distributed to obtain mildly diabetic by streptozotocin induction at birth and the non-diabetic females given vehicle. At adulthood, pregnant rats were put at random into sedentary non-diabetic rats (ND); exercise non-diabetic rats (NDEx); sedentary diabetic rats (D); and exercise diabetic rats (DEx). The rats of the groups submitted to moderate intensity carried loads equivalent to 4% of body weight. On day 17 of gestational day, all rats were submitted to oral glucose tolerance test (OGTT). Next day (GD18), the rats were anesthetized and killed to count implantation sites and to collect placentas, blood, and muscle samples for biochemical biomarkers and pancreas for immunohistochemical analysis. The moderate exercise used was not sufficient to stimulate the aerobic pathway but presented positive results on glucose metabolism, lower embryo postimplantation loss, and pancreatic morphology compared with the sedentary diabetic group. However, the DEx group showed muscular damage, decreased antioxidant defense, and lipid peroxidation. Thus, the moderate-intensity exercise reduces glycemic levels during OGTT and causes no damage to non-diabetic rats related to other analyzed parameters in this study. The exercised diabetic rats present better glycemic metabolism in OGTT, islet pancreatic morphology, and embryofetal development. However, it is necessary an adjustment in this exercise intensity to improve the effectiveness of aerobic training for reduction of maternal muscular and lipid membrane damages.

Male fetal sex affects uteroplacental angiogenesis in growth restriction mouse model†

Abnormally increased angiotensin II activity related to maternal angiotensinogen (AGT) genetic variants, or aberrant receptor activation, is associated with small-for-gestational-age babies and abnormal uterine spiral artery remodeling in humans. Our group studies a murine AGT gene titration transgenic (TG; 3-copies of the AGT gene) model, which has a 20% increase in AGT expression mimicking a common human AGT genetic variant (A[-6]G) associated with intrauterine growth restriction (IUGR) and spiral artery pathology. We hypothesized that aberrant maternal AGT expression impacts pregnancy-induced uterine spiral artery angiogenesis in this mouse model leading to IUGR. We controlled for fetal sex and fetal genotype (e.g., only 2-copy wild-type [WT] progeny from WT and TG dams were included). Uteroplacental samples from WT and TG dams from early (days 6.5 and 8.5), mid (d12.5), and late (d16.5) gestation were studied to assess uterine natural killer (uNK) cell phenotypes, decidual metrial triangle angiogenic factors, placental growth and capillary density, placental transcriptomics, and placental nutrient transport. Spiral artery architecture was evaluated at day 16.5 by contrast-perfused three-dimensional microcomputed tomography (3D microCT). Our results suggest that uteroplacental angiogenesis is significantly reduced in TG dams at day 16.5. Males from TG dams are associated with significantly reduced uteroplacental angiogenesis from early to late gestation compared with their female littermates and WT controls. Angiogenesis was not different between fetal sexes from WT dams. We conclude that male fetal sex compounds the pathologic impact of maternal genotype in this mouse model of growth restriction.

Neonate born with ischemic limb to a COVID-19 positive mother: management and review of literature

Objectives

To describe challenges in diagnosis and treatment of congenital neonatal gangrene lesions associated with history of maternal coronavirus disease 2019 (COVID-19) infection.

Case presentation

A preterm neonate was born with upper extremity necrotic lesions and a history of active maternal COVID-19 infection. The etiology of his injury was challenging to deduce, despite extensive hypercoagulability work-up and biopsy of the lesion. Management, including partial forearm salvage and hand amputation is described.

Conclusions

Neonatal gangrene has various etiologies, including compartment syndrome and intrauterine thromboembolic phenomena. Maternal COVID-19 can cause intrauterine thrombotic events and need to be considered in a differential diagnosis.

Exploring the impact of HIV infection and antiretroviral therapy on placenta morphology

INTRODUCTION

Women living with HIV experience more adverse birth outcomes; the mechanisms are not fully understood. We examined placenta morphology and associations with birth outcomes in a Canadian cohort of women living with HIV (HIV⁺) on antiretroviral therapy (ART) from conception and HIV-uninfected (HIV^-) women.

METHODS

Term placentas from 94 women (40 HIV^-, 54 HIV⁺) were studied. Trimmed placenta weight was collected. Placenta digital photos were used to compute morphometric parameters. Regression models investigated associations between log-transformed placenta parameters and birth outcomes.

RESULTS

We observed a trend towards lower placenta weight and smaller placenta area in the HIV⁺ group, both of which were significantly associated with small for gestational age births. HIV⁺ serostatus was associated with 6-fold (95%CI 2-20) greater odds of having placenta area in the lowest quartile (<236 cm²). Cord marginality (distance from the edge) was significantly lower in the HIV⁺ group (p = 0.004), with 35% of placenta having an abnormal (marginal or velamentous) cord insertion vs. 12.5% in the HIV^- group (p = 0.01). Velamentous cord insertion was seen in 13% of placentas in the HIV⁺ vs. 0% in HIV^- group (p = 0.02). A significant correlation between cord marginality and placenta thickness was observed in the HIV^- group, with a more marginal cord being associated with a thicker placenta. This correlation was not observed in the HIV⁺ group. HIV⁺ placentas exposed to protease inhibitors were significantly less circular compared to the HIV^- group (p = 0.03).

CONCLUSION

Our data suggest that HIV/ART exposure affects placenta morphology and is associated with higher rates of abnormal cord insertion.

Associations of prenatal heavy metals exposure with placental characteristics and birth weight in Hangzhou Birth Cohort: Multi-pollutant models based on elastic net regression

BACKGROUND

The human placenta is vulnerable to environmental pollutants, but the associations between exposure to multiple, correlated metals and placental characteristics have not been studied.

METHODS

The current study population was derived from the Hangzhou Birth Cohort Study. Whole blood and urine samples were collected from mothers during 20-28 gestational week. The concentrations of 11 metals in blood and 11 metals in urine were evaluated by inductively coupled plasma mass spectrometry. The data on placental characteristics and birth weight were retrieved from medical records. The elastic net (ENET) model combined with unpenalized regression model was employed to estimate the relationship between levels of metals and placental characteristics (placental weight, chorionic disc area, chorionic disc eccentricity, placental thickness, placental-fetal birth weight ratio) and birth weight. Mediation analysis was performed to explore the mediated effect of placenta on the association of prenatal metals exposure with birth weight.

RESULTS

Among 512 participants with urine metal levels, the ENET model retained Cadmium (Cd) and Selenium (Se) for placental weight. Further unpenalized regression model including Cd and Se simultaneously showed that one-unite increased natural-logarithm (ln)-transformed urine creatinine corrected (CC) Cd levels was associated with reductions in placental weight of -7.2 g (95% confidence interval (CI): -14.0, -0.4). Among 483 participants with blood metal levels, similarly, blood Cd levels were negatively associated with placental weight (β = -7.5, 95% CI: -17.0, 1.9). Furthermore, mediation analysis demonstrated that urine CC-Cd level was associated with a 21.3 g decrease (95% CI: -42.0, -2.5, p = 0.024) in birth weight through a reduction in placental weight, while blood Cd levels presented a negative association at borderline significance.

CONCLUSION

Our findings suggest a mediation effect of the placenta in the relationship between prenatal Cd exposure and lower birth weight. Additional studies with repeated assessment of exposure and more placental parameters are warranted to confirm this relationship.

Paternal low protein diet and the supplementation of methyl-donors impact fetal growth and placental development in mice

Introduction

Paternal low-protein diet can alter sperm methylation status, fetal growth and program offspring ill-health, however its impact on the placenta remains poorly defined. Here we examine the influence paternal low-protein diet has on fetal and placental development and the additional impact of supplementary methyl-donors on fetoplacental physiology.

Methods

Male C57BL/6J mice were fed a control normal protein diet (NPD; 18% protein), a low-protein diet (LPD; 9% protein) or LPD with methyl-donor supplementation (MD-LPD; choline chloride, betaine, methionine, folic acid, vitamin B12) for a minimum of 8 weeks. Males were mated with 8–11 week old female C57BL/6J mice and fetal and placental tissue collected on embryonic day 17.5.

Results

Paternal LPD was associated with increased fetal weights compared to NPD and MD-LPD with 22% fetuses being above the 90th centile for fetal weight. However, LPD and MD-LPD placental weights were reduced when compared to NPD. Placentas from LPD fathers demonstrated a reduced junctional zone area and reduced free-fatty acid content. MD-LPD placentas did not mirror these finding, demonstrating an increased chorion area, a reduction in junctional-specific glycogen staining and reduced placental Dnmt3bexpression, none of which were apparent in either NPD or LPD placentas.

Discussion

A sub-optimal paternal diet can influence fetal growth and placental development, and dietary methyl-donor supplementation alters placental morphology and gene expression differentially to that observed with LPD alone. Understanding how paternal diet and micro-nutrient supplementation influence placental development is crucial for determining connections between paternal well-being and future offspring health.

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Paternal low protein diet (LPD) increased late gestation fetal weight.

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Supplementing the LPD with methyl donors (MD-LPD) normalised fetal weight.

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Placental weight and morphology are altered by both LPD and MD-LPD.

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Placental metabolite content and gene expression were perturbed by paternal LPD and MD-LPD.

Ozone-induced fetal growth restriction in rats is associated with sexually dimorphic placental and fetal metabolic adaptation

Objective

The importance of the placenta in mediating the pre- and post-natal consequences of fetal growth restriction has been increasingly recognized. However, the influence of placental sexual dimorphism on driving these outcomes has received little attention. The purpose of this study was to characterize how sex contributes to the relationship between placental metabolism and fetal programming utilizing a novel rodent model of growth restriction.

Methods

Fetal growth restriction was induced by maternal inhalation of 0.8 ppm ozone (4 h/day) during implantation receptivity (gestation days [GDs] 5 and 6) in Long-Evans rats. Control rats were exposed to filtered air. At GD 21, placental and fetal tissues were obtained for metabolic and genomic assessments.

Results

Growth-restricted male placentae exhibited increased mitochondrial biogenesis, increased oxygen consumption, and reduced nutrient storage. Male growth-restricted fetuses also had evidence of reduced adiposity and downregulation of hepatic metabolic signaling. In contrast, placentae from growth-restricted females had elevated markers of autophagy accompanied by an observed protection against hepatic metabolic perturbations. Despite this, growth restriction in females induced a greater number of hypothalamic gene and pathway alterations compared to growth-restricted males.

Conclusions

Increases in mitochondrial metabolism in growth-restricted male placentae likely initiates a sequela of adaptations that promote poor nutrient availability and adiposity. Divergently, the female placenta expresses protective mechanisms that may serve to increase nutrient availability to support fetal metabolic development. Collectively, this work emphasizes the importance of sex in mediating alterations in placental metabolism and fetal programming.

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Peri-implantation exposure to the gaseous air pollutant ozone impairs fetal growth.

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Ozone-induced, growth-restricted male placentae have increased mitochondrial biogenesis and oxidative consumption.

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Female growth-restricted placentae show increased inflammatory and autophagy-like responses.

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Placental metabolic adaptations to growth restriction were associated with sexually dimorphic perturbations in fetal tissues.

Association between maternal hemoglobin concentration and placental weight to birthweight ratio: The Japan Environment and Children's Study (JECS)

INTRODUCTION

Past studies have shown that maternal anemia is associated with a heavy placenta or a higher placental weight/birthweight (PW/BW) ratio. Although these findings suggest a non-linear relationship between maternal hemoglobin concentration and PW/BW ratio, this relationship has not been closely examined.

METHODS

We evaluated 83,354 singletons and their mothers in a nation-wide birth cohort study, the Japan Environment and Children's Study (JECS). The associations between maternal hemoglobin concentration and placental weight, birthweight, and PW/BW ratio were assessed.

RESULTS

Mean placental weight was significantly higher in women with moderate or severe anemia (576 [183] g), but not in women with elevated hemoglobin levels (564 [117] g), compared with in women with normal hemoglobin levels (560 [115] g). In contrast, mean PW/BW ratio was significantly higher in women with moderate or severe anemia (0.190 [0.049]) or elevated hemoglobin levels (0.189 [0.033]) than in women with normal hemoglobin levels (0.185 [0.033]). In a regression analysis with cubic spline, a U-shaped relationship was found between maternal hemoglobin concentration and PW/BW ratio.

DISCUSSION

We demonstrated non-linear and concentration-dependent relationships between maternal hemoglobin concentration and placental weight, birthweight, and PW/BW ratio. Although the mechanisms underlying these associations are not fully understood, we suggest that low or elevated hemoglobin concentration may lead to placental compensatory hypertrophy and fetal growth restriction. Prevention and proper management of anemia before and during pregnancy are important for a well-functioning placenta and favorable fetal growth.

Tracking placental development in health and disease

Pre-eclampsia and fetal growth restriction arise from disorders of placental development and have some shared mechanistic features. Initiation is often rooted in the maldevelopment of a maternal-placental blood supply capable of providing for the growth requirements of the fetus in later pregnancy, without exerting undue stress on maternal body systems. Here, we review normal development of a placental bed with a safe and adequate blood supply and a villous placenta-blood interface from which nutrients and oxygen can be extracted for the growing fetus. We consider disease mechanisms that are intrinsic to the maternal environment, the placenta or the interaction between the two. Systemic signalling from the endocrine placenta targets the maternal endothelium and multiple organs to adjust metabolism for an optimal pregnancy and later lactation. This signalling capacity is skewed when placental damage occurs and can deliver a dangerous pathogenic stimulus. We discuss the placental secretome including glycoproteins, microRNAs and extracellular vesicles as potential biomarkers of disease. Angiomodulatory mediators, currently the only effective biomarkers, are discussed alongside non-invasive imaging approaches to the prediction of disease risk. Identifying the signs of impending pathology early enough to intervene and ameliorate disease in later pregnancy remains a complex and challenging objective.

Impact of World War 1 on placenta weight, birth weight and other anthropometric parameters of neonatal health

BACKGROUND

Wars do not only affect combatant countries, populations in neutral zones can be afflicted by circumjacent conflicts as well, posing a great health burden on mothers and newborns. As neonatal health remains an ongoing cause for concern, identifying determinants that impede fetal growth is crucial. Under this pretext, the study aimed to analyze the impact of World War 1 in the neutral city of Basel on neonatal health by assessing changes in anthropometric parameters.

METHODS

A retrospective analysis of yearly cross sections of term births in the maternity hospital of Basel from 1912 to 1923 was conducted (n = 3718). We tested adjusted anthropometry for time trends in comparison to a pre-war baseline, including birth weight, placenta weight, birth length, ponderal index and gestational age. Interrelations of placenta weights and birth weights were examined separately through birth weight to placenta weight (BW/PW) ratios and residuals of placenta weight to birth weight regressions.

RESULTS

Birth weights, placenta weights and residuals were at their lowest in 1918/19, a trend not reflected in BW/PW ratios. Birth lengths remained low while ponderal indexes declined during the entire period of war, gestational age remained rather stable.

DISCUSSION

1918/19 were the pinnacle years for the population of Basel, who were suffering from general detrimental economic conditions, a food supply crisis and an outbreak of the Spanish Flu. These adverse circumstances coincided with low birth and placenta weights, residuals depicting the correlation of birth weights to placental weights more closely than bw/pw ratios.

Protease-activated receptor 2 contributes to placental development and fetal growth in mice

BACKGROUND

Protease-activated receptor 2 (PAR2) is activated by serine proteases such as coagulation tissue factor/VIIa complex, factor Xa or trypsin and is pro-angiogenic in several disease models. Impaired angiogenesis in placenta causes placental dysfunction and fetal growth restriction. PAR2 is expressed in the placenta trophoblast. However, the role of PAR2 in pregnancy remains unknown.

OBJECTIVE

The present study aimed to examine the role of PAR2 in placental development and fetal growth using a murine model.

METHODS

PAR2^-/- or PAR2^+/+ mice in the ICR background were used. Female PAR2^-/- mice were mated with male PAR2^-/- mice, and female PAR2^+/+ mice were mated with male PAR2^+/+ mice to obtain PAR2^-/- and PAR2^+/+ fetuses, respectively. The day a virginal plug was observed in the morning was determined as 0.5-day post-coitum (dpc). Pregnant mice were sacrificed on 13.5 or 18.5 dpc to collect samples.

RESULTS

A deficiency of PAR2 significantly reduced the fetal and placental weight and impaired placental labyrinth development in mice on 18.5 dpc. Collagen IV expression in placenta labyrinth was smaller in PAR2 knockout mice compared to that of wild-type mice. A deficiency of PAR2 also reduced the expression levels of genes related to angiogenesis and coagulation in placenta.

CONCLUSION

Our data suggest that PAR2 is required for fetal growth and angiogenesis in the placenta and is thus important for a normal pregnancy.

Persistent DNA Damage and Senescence in the Placenta Impacts Developmental Outcomes of Embryos

Cohesin is an evolutionarily conserved chromosome-associated protein complex essential for chromosome segregation, gene expression, and repair of DNA damage. Mutations that affect this complex cause the human developmental disorder Cornelia de Lange syndrome (CdLS), thought to arise from defective embryonic transcription. We establish a significant role for placental defects in the development of CdLS mouse embryos (Nipbl and Hdac8). Placenta is a naturally senescent tissue; we demonstrate that persistent DNA damage potentiates senescence and activates cytokine signaling. Mutant embryo developmental outcomes are significantly improved in the context of a wild-type placenta or by genetically restricting cytokine signaling. Our study highlights that cohesin is required for maintaining ploidy and the repair of spontaneous DNA damage in placental cells, suggesting that genotoxic stress and ensuing placental senescence and cytokine production could represent a broad theme in embryo health and viability.

The Role of circRNA-SETD2/miR-519a/PTEN Axis in Fetal Birth Weight through Regulating Trophoblast Proliferation

Abnormal birth weight is the one of the major causes of adulthood diseases such as obesity, metabolic syndrome, cardiovascular disease, type 2 diabetes, and hypertension. Accumulating evidence has suggested that the placental trophoblast is one of the most important reasons that influence birth weight. Our previous study showed that miR-519a are correlated with low fetal birth weight through regulating trophoblast proliferation. To further clarify the detailed mechanisms on how it is regulated, we screened the placental-specific circular RNAs (circRNAs) via microarray assay. The result identified that circ-SETD2 was highly expressed in the placenta of the patients with fetal macrosomia compared with healthy donors. Furthermore, bioinformatic analyses and the luciferase reporter assay revealed that miR-519a possessing the binding sites for both circ-SETD2 and phosphate and tensin homolog was deleted on chromosome 10 (PTEN). Interestingly, upregulation of circ-SETD2 enhanced the proliferation and invasion of the human trophoblast-like cell line HTR8/SVneo cell. A parallel study performed by Western blotting showed that overexpression of circ-SETD2 reduced miR-519a levels and increased PTEN levels in HTR8/SVneo cells. Importantly, the enhancement of HTR8/SVneo cell activity by circ-SETD2 overexpression was nullified when the cells were cotransfected by circ-SETD2 and miR-519a, suggesting the involvement of the circ-SETD2/miR-519a/PTEN axis in trophoblast activity. Taken together, we illustrate the role of circ-SETD2, as an upstream signaling of miR-519a/PTEN, in placenta development via regulating trophoblast proliferation and invasion. These findings improve our understanding of the mechanisms of progression of fetal macrosomia and will guide future development of therapeutic strategies against the disease by targeting the circ-SETD2/miR-519a/PTEN axis.

Sp1 participates in the cadmium-induced imbalance of the placental glucocorticoid barrier by suppressing 11β-HSD2 expression

Cadmium (Cd) is widely present in the environment as a heavy metal poison. Prenatal Cd exposure can damage the placental glucocorticoid barrier, leading to foetal growth restriction (FGR), but the molecular mechanism is unknown. We aimed to study the effects of prenatal Cd exposure on 11β-HSD2 and its possible involvement in Cd induced damage in the placental glucocorticoid barrier. Pregnant rats were treated with CdCl2 (1.0 mg/kg/day) by gavage from gestational day (GD) 9-19. Maternal exposure to Cd increased the FGR rate of the offspring, and the levels of corticosterone in the placenta, maternal and foetal serum. Further in vitro experiments with placenta or JEG3 cells indicated that Cd was able to decrease 11β-HSD2 and Sp1 expression in trophoblast cells but did not affect 11β-HSD1. Additionally, decreased p300 and Sp1 enrichment at the 11β-HSD2 promoter region was observed in the cells treated with Cd. Decreasing or increasing Sp1 expression accordingly inhibited or promoted the expression of 11β-HSD2 and further decreased or increased p300 and Sp1 enrichment at the 11β-HSD2 promoter region. In conclusion, Cd inhibits the expression of 11β-HSD2 by affecting the binding of p300 to 11β-HSD2 via a decrease in Sp1 expression, which damages the placental glucocorticoid barrier and exposes the foetus to excessive glucocorticoids, resulting in FGR. These findings reveal a possible underlying molecular mechanism by which Cd exposure leads to FGR.

Associations of maternal ambient temperature exposures during pregnancy with the placental weight, volume and PFR: A birth cohort study in Guangzhou, China

BACKGROUND

The placenta performs crucial functions to ensure normal fetal development. Experimental studies have indicated associations between exposure to elevated temperatures during pregnancy and reduction in placental weight and volume. However, epidemiological studies in humans are lacking.

OBJECTIVE

To estimate the associations between prenatal exposure to ambient temperature with placental weight, volume, and the placental weight to birth weight ratio (PFR).

METHODS

We conducted a prospective birth cohort study using the Prenatal Environment and Offspring Health Cohort (PEOH Cohort) beginning in 2016 in Guangzhou, China. Women in early pregnancy were recruited and followed up during their hospitalization for childbirth. An inverse distance-weighted method was employed to estimate the average temperature exposure of every 4 weeks as well as the trimester-specific average temperature exposure at the individual's residential address. A generalized linear model was applied to estimate the effects of temperature exposure during pregnancy on the placental weight, volume, and PFR.

RESULTS

A total of 4051 pregnant women were enrolled. Compared with the reference temperature of 20 °C, maternal exposure to 29 °C (95th centile) during late pregnancy was associated with an average of -6.03 g (95% confidence interval [CI]: -11.28 g, -0.78 g) in placental weight, -16.15 cm³ (95% CI: -26.24 cm³, -6.07 cm³) in placental volume, and 0.26 (95% CI: 0.07, 0.45) in PFR. The peak effects of high temperatures on placental weight, volume, and PFR were found from 29 to 32 weeks (β = -3.79 g, 95% CI: -8.39 g, 0.82 g), 37 to 40 weeks (β = -19.34 cm³, 95% CI: -30.99 cm³, -7.69 cm³), and 25 to 28 weeks (β = 0.35, 95% CI: 0.04, 0.66), respectively.

CONCLUSIONS

Maternal exposure to elevated temperatures was associated with a decrease in placental weight and volume and an increase in PFR. The associations were stronger when exposures occurred during late pregnancy.

Association between maternal active smoking during pregnancy and placental weight: The Japan environment and Children's study

INTRODUCTION

Maternal smoking during pregnancy is a well-known risk factor for reduced birthweight. However, research investigating the association between maternal smoking and placental weight is scarce and inconsistent. Our study was conducted to evaluate the association between maternal smoking and placental weight and placental weight/birthweight ratio (PW/BW ratio).

METHODS

We used data from a birth cohort study, the Japan Environment and Children's Study (JECS). Main outcome measures were placental weight, PW/BW ratio, and the risk of high PW/BW ratio. High PW/BW ratio was defined as PW/BW ratio above the 90th percentile for gestational age and sex of offspring. The association between maternal smoking and placental weight was estimated as crude and as adjusted beta coefficients by applying linear regression analyses. Logistic regression analyses were also performed to estimate the association between maternal smoking and the risk of high PW/BW ratio.

RESULTS

Of the 91,951 pregnant women, the mean placental weight and the mean PW/BW ratio were lowest for the group of women who had never smoked. Smokers had higher odds ratio for high PW/BW ratio compared with non-smokers. Furthermore, among smokers, the mean placental weight and mean PW/BW ratio were lowest in women who smoked less than 5 daily cigarettes, and highest in women who smoked 20 or more daily cigarettes during pregnancy.

DISCUSSION

Placental weight was greater and PW/BW ratio was higher among smokers compared with non-smokers. Moreover, the number of daily cigarettes was positively associated with heavy placental weight.

The placenta in fetal growth restriction: What is going wrong?

The placenta is essential for the efficient delivery of nutrients and oxygen from mother to fetus to maintain normal fetal growth. Dysfunctional placental development underpins many pregnancy complications, including fetal growth restriction (FGR) a condition in which the fetus does not reach its growth potential. The FGR placenta is smaller than normal placentae throughout gestation and displays maldevelopment of both the placental villi and the fetal vasculature within these villi. Specialized epithelial cells called trophoblasts exhibit abnormal function and development in FGR placentae. This includes an altered balance between proliferation and apoptotic death, premature cellular senescence, and reduced colonisation of the maternal decidual tissue. Thus, the placenta undergoes aberrant changes at the macroscopic to cellular level in FGR, which can limit exchange capacity and downstream fetal growth. This review aims to compile stereological, in vitro, and imaging data to create a holistic overview of the FGR placenta and its pathophysiology, with a focus on the contribution of trophoblasts.

Prenatal Nutrition Containing Bisphenol A Affects Placenta Glucose Transfer: Evidence in Rats and Human Trophoblast

This work aims to clarify the effect of dietary supplementation with Bisphenol A (BPA), a chemical widely present in beverage and food containers, on placental glucose transfer and pregnancy outcome. The study was performed on female Sprague Dawley rats fed with a diet containing BPA (2.5, 25 or 250 μg/Kg/day) for a period of a month (virgin state) plus 20 days during pregnancy. Western blot analysis and immunohistochemistry were performed in placental tissues for glucose type 1 transporter (GLUT1). Furthermore, human trophoblast, HTR8-SV/neo cells, were used to evaluate the effect of BPA on glucose transport and uptake. Studies in rats showed that food supplementation with BPA, produces a higher fetal weight (FW) to placenta weight (PW) ratio at the lowest BPA concentration. Such low concentrations also reduced maternal weight gain in late pregnancy and up-regulated placental expression of GLUT1. Treatment of HTR8-SV/neo with the non-toxic dose of 1 nM BPA confirmed up-regulation of GLUT1 expression and revealed higher activity of the transporter with an increase in glucose uptake and GLUT1 membrane translocation. Overall, these results indicate that prenatal exposure to BPA affects pregnancy and fetal growth producing changes in the placental nutrients-glucose transfer.

Maternal iron nutriture modulates placental development in a rat model of fetal alcohol spectrum disorder

Prenatal alcohol exposure (PAE) causes developmental abnormalities known as fetal alcohol spectrum disorder (FASD). Maternal iron status modulates the severity of these defects in the offspring. Because the placenta is central in supporting fetal development, we investigated whether maternal iron status similarly modulates alcohol's effects in the placenta. We hypothesized that PAE causes placental insufficiency by decreasing placental weight and efficiency, and we hypothesized that these are worsened by maternal iron deficiency (ID) and alleviated by dietary iron fortification (IF). We also determined whether altered placental iron flux and inflammatory balance contribute to placental insufficiency. Pregnant Long-Evans rats consumed an iron-deficient (ID; 2-6 ppm), iron-sufficient (IS; 100 ppm), or iron-fortified (IF; 500 ppm) diet. Alcohol (5 g/kg body weight) or isocaloric maltodextrin (MD) was gavaged daily from gestational day (GD) 13.5-19.5. Placental outcomes were evaluated on GD20.5. PAE reduced fetal weight (p < 0.0001), placental weight (p = 0.0324), and placental efficiency (p = 0.0043). PAE downregulated placental transferrin receptor (p = 0.0032); it also altered placental Il1b and Tnf expression and the Il6:Il10 ratio (p = 0.0337, 0.0300, and 0.0034, respectively) to generate a response favoring inflammation. ID-PAE further reduced fetal growth and placental efficiency and induced a heightened pro-inflammatory placental profile. IF did not rescue the alcohol-reduced fetal weight, but it normalized placental efficiency and decreased placental inflammation. These placental cytokines correlated with fetal and placental growth, and explained 45% of the variability in fetal weight and 20% of the variability in placental efficiency. In summary, alcohol induces placental insufficiency and is associated with a pro-inflammatory cytokine profile exacerbated by maternal ID and mitigated by maternal IF. Because the placenta is closely linked to intrauterine growth, the placental insufficiency reported here may correlate with the lower birth weights in a subgroup of individuals who experienced PAE.

Placental histopathology in sickle cell disease: A descriptive and hypothesis-generating study

INTRODUCTION

Abnormal placental development is a unifying factor amongst many adverse pregnancy outcomes (APOs) in Sickle Cell Disease (SCD). Our aim was to describe placental histopathologic findings in women with SCD and their relationship with APOs, and to explore the association between antenatal sonographic findings and placental pathology.

METHODS

Retrospective single-centre case series of all pregnant women with SCD (January 2000-December 2017), pregnancy beyond 20 weeks' gestation, and available placenta histopathology. APOs included intrauterine fetal death, early neonatal death, preterm birth, small for gestational age, and hypertensive disorders of pregnancy. Review of images for mid-pregnancy ultrasound and one proximal to delivery was completed, blinded to clinical outcomes and histopathology results. Gross and histopathologic findings were reviewed and characterized per published classification.

RESULTS

Of 72 placentas, abnormalities were present in 69%, with Maternal Vascular Malperfusion (MVM) noted in 40%. APOs were encountered in 61% overall and in 79% of those with MVM. Neither SCD genotype nor severe maternal anemia had an influence on histopathologic placental features. Presence of high-resistance uterine artery waveforms at mid-trimester ultrasound was strongly associated with APOs and with abnormal findings on placental histopathology, most notably MVM. MVM was strongly associated with small for gestational age infants, preterm birth, and stillbirth.

DISCUSSION

MVM is the predominant lesion in placentas of women with SCD and is strongly associated with APOs. Mid-trimester ultrasound can identify a subset of women at risk. Future research into advanced imaging modalities to aid in antenatal diagnosis alongside investigations of potentially beneficial therapies is needed.

Maternal supplementation with citrulline or arginine during gestation impacts fetal amino acid availability in a model of intrauterine growth restriction (IUGR)

BACKGROUND

Supplementing maternal diet with citrulline or arginine during gestation was shown to enhance fetal growth in a model of IUGR induced by maternal dietary protein restriction in the rat.

OBJECTIVE

The aims of this study were to determine in the same model whether maternal supplementation with citrulline or arginine would increase 1) citrulline and arginine concentration in fetal circulation; 2) the expression of placental amino acid transporters, and 3) the fetal availability of essential amino acids.

METHODS

Pregnant rats (n = 8 per group) were fed either an isocaloric control (20% protein, NP) or a low protein (LP, 4% protein) diet, either alone or supplemented with 2 g/kg/d of l-citrulline (LP + CIT) or isonitrogenous Arginine (LP + ARG) in drinking water throughout gestation. Fetuses were extracted by C-section on the 21st day of gestation. The gene expression of system A (Slc38a1, Slc38a2, and Slc38a4) and L (Slc7a2, Slc7a5, Slc7a8) amino acid transporters was measured in placenta and amino acid concentrations determined in maternal and fetal plasma.

RESULTS

Maternal LP diet decreased fetal (4.01 ± 0.03 vs. 5.45 ± 0.07 g, p < 0.0001) and placental weight (0.617 ± 0.01 vs. 0.392 ± 0.04 g, p < 0.001), by 26 and 36% respectively, compared with NP diet. Supplementation with either CIT or ARG increased fetal birth weight by ≈ 5 or 11%, respectively (4.21 ± 0.05 and 4.48 ± 0.05 g vs. 4.01 ± 0.03 g, p < 0.05). CIT supplementation produced a 5- and 2-fold increase in fetal plasma citrulline and arginine, respectively, whereas ARG supplementation only increased fetal arginine concentration. LP diet led to lower placental SNAT 4 mRNA, and higher LAT2 and SNAT1 expression, compared with NP. SNAT4, 4hFC, LAT2 mRNA were up-regulated in LP + CIT and LP + ARG group compared with the un-supplemented LP group. Higher level of LAT1 mRNA was also observed in the LP + CIT group than in the LP group (p < 0.01). SNAT2 expression was unchanged in response to CIT or ARG supplementation. Fetal amino acid concentrations were decreased by LP diet, and were not restored by CIT or ARG supplementation.

CONCLUSIONS

The current findings confirm supplementation with citrulline or arginine enhances fetal growth in a rat model of IUGR. They further suggest that: 1) citrulline and arginine administered orally to the pregnant mother may reach fetal circulation; 2) citrulline effectively raises fetal arginine availability; and 3) although it failed to increase the concentrations of essential amino acids in fetal plasma, citrulline or arginine supplementation upregulates the gene expression of several placental amino acid transporters.

Pregnant women with gestational diabetes and with well controlled glucose levels have decreased concentrations of individual fatty acids in maternal and cord serum

AIMS/HYPOTHESIS

Both arachidonic acid (AA, 20:4 n-6) and docosahexaenoic acid (DHA,22:6 n-3), long-chain polyunsaturated fatty acids (LCPUFA), are involved in fetal development and, based on their percentage compositions, appear to be specifically accumulated in fetal circulation in a proposed phenomenon known as biomagnification. Discrepancies exist in the literature concerning the effect of gestational diabetes mellitus (GDM) on circulating fatty acids. Our objective was to analyse individual fatty acid concentrations in a large cohort of maternal and cord paired serum samples from pregnant women with and without GDM.

METHODS

Overnight fasted maternal and cord blood paired samples from 84 women with GDM and well controlled blood glucose levels and 90 healthy pregnant women (controls) were drawn at term. Individual fatty acids within total serum lipids were analysed by gas chromatography and expressed both as concentrations of fatty acid (mmol/l) and as a percentage of total fatty acids.

RESULTS

In the serum of overnight fasted pregnant women with GDM, the concentrations of most fatty acids were lower than in control women, except for AA and DHA, which remained the same. The concentrations of most fatty acids in cord serum were also lower in the GDM group than in the control group, except for α-linolenic acid (ALA,18:3 n-3), which was higher in the GDM group. In both groups, the concentrations of all fatty acids were lower in cord serum than in maternal serum. In GDM participants only, a positive and significant correlation between cord and maternal serum concentration of AA and DHA was observed.

CONCLUSIONS/INTERPRETATION

The expression of fatty acids in molar concentrations reveals that GDM decreases the concentration of most fatty acids in both maternal and cord serum. There is a high fetal dependence on maternal AA and DHA, but our findings do not support the existence of a fetal biomagnification of those two LCPUFA.

Prenatal dexamethasone exposure exerts sex-specific effect on placental oxygen and nutrient transport ascribed to the differential expression of IGF2

Background

Clinical studies have showed that dexamethasone exposure during pregnancy could cause fetal growth retardation, but the mechanism by which prenatal dexamethasone exposure influences placental nutrient transport is still unclear. This study investigated the impacts of prenatal dexamethasone on the placental oxygen and nutrient transport.

Methods

Pregnant Wistar rats were subcutaneously administered with dexamethasone from day 9 to day 20 of gestation at 0.2 or 0.8 mg/kg·d. Pregnant rats were sacrificed on gestational day 20. The placental tissue was collected for analysis.

Results

Prenatal dexamethasone exposure (PDE) declined the fetal weight and increased the intrauterine growth retardation (IUGR) rate in a dose-dependent manner. The total placental volume and the length, density and surface area of fetal capillaries in the labyrinth zone reduced in a dose-dependent manner. In addition, the thickness of syncytial membrane dose-dependently increased, resulting in a dose-dependent decrease in oxygen diffusion capacity. Furthermore, after PDE, the nutrient transport area and oxygen diffusion capacity of male placenta were lower than that of female placenta. The mRNA and protein expression of placental nutrient transporters including glucose transporter 1 (GLUT1), glucose transporter 3 (GLUT3), L-type amino acid transporter 1 (LAT1), lipoprotein lipase (LPL) and scavenger receptor class B type 1 (SRB1) increased in female placenta. However, in male placenta, the expression of LAT1, LPL and SRB1 was significantly decreased and GLUT1 and GLUT3 have a decrease trend. We further investigated the expression of insulin-like growth factor 1 (IGF1) and insulin-like growth factor 2 (IGF2) related to placental and fetal growth and development. Our study showed that the expression of IGF1 was significantly decreased both in male and female placentas after PDE. But the expression of IGF2 was significantly increased in female placentas while significantly decreased in male placentas.

Conclusions

Our study shows prenatal dexamethasone exposure exerts sex-specific influence on the placental oxygen and nutrient transport. This might be ascribed to the differential expression of IGF2 after PDE. These findings provide evidence on the dexamethasone-induced toxicity to the placenta and fetal development.

Changes in Placental Nutrient Transporter Protein Expression and Activity Across Gestation in Normal and Obese Women

Fetal growth and development are dependent on placental nutrient transport. The syncytiotrophoblast (ST) and its two polarized plasma membranes, the maternal-facing microvillous membrane (MVM) and fetal-facing basal membrane (BM), represent the primary barrier in the human placenta, controlling transplacental transfer of small solutes. MVM and BM nutrient transporter expression and activity are increased in obese mothers delivering large babies. However, placental nutrient transporter expression and activity in early gestation in normal and obese women are largely unknown. Placentas from normal BMI and obese women at 6-24 weeks of gestation, and term placentas from normal BMI women, were collected and ST plasma membranes isolated. The activity and protein expression of amino acid, glucose, and fatty acid transporters was assessed. No significant differences were observed in placental nutrient transporter protein expression between normal BMI and obese women in early pregnancy. In the MVM, system A amino acid activity (p = 0.02), SNAT2 (p < 0.0001), SNAT4 (p < 0.001), and GLUT1 (p = 0.01) protein expression were higher at term compared with early gestation. In contrast, MVM system L activity (p = 0.001), FATP4 (p = 0.03), and FATP6 (p = 0.009) protein expression were lower at term compared with early pregnancy. In the BM, there was no change in system L activity across gestation; however, BM FATP6 (p = 0.002) protein expression was lower at term compared with early pregnancy. These results suggest that placental transport of amino acids, glucose, and fatty acids are subjected to coordinated regulation across gestation to meet a fetal nutrient demand that changes with advancing pregnancy.

Evaluation of Maternal, Embryo, and Placental Effects in CD-1 Mice following Gestational Exposure to Perfluorooctanoic Acid (PFOA) or Hexafluoropropylene Oxide Dimer Acid (HFPO-DA or GenX)

BACKGROUND

Perfluorooctanoic acid (PFOA) is a poly- and perfluoroalkyl substance (PFAS) associated with adverse pregnancy outcomes in mice and humans, but little is known regarding one of its replacements, hexafluoropropylene oxide dimer acid (HFPO-DA, referred to here as GenX), both of which have been reported as contaminants in drinking water.

OBJECTIVES

We compared the toxicity of PFOA and GenX in pregnant mice and their developing embryo-placenta units, with a specific focus on the placenta as a hypothesized target.

METHODS

Pregnant CD-1 mice were exposed daily to PFOA (0, 1, or 5mg/kg) or GenX (0, 2, or 10mg/kg) via oral gavage from embryonic day (E) 1.5 to 11.5 or 17.5 to evaluate exposure effects on the dam and embryo-placenta unit. Gestational weight gain (GWG), maternal clinical chemistry, maternal liver histopathology, placental histopathology, embryo weight, placental weight, internal chemical dosimetry, and placental thyroid hormone levels were determined.

RESULTS

Exposure to GenX or PFOA resulted in increased GWG, with increase in weight most prominent and of shortest latency with 10mg/kg/d GenX exposure. Embryo weight was significantly lower after exposure to 5mg/kg/d PFOA (9.4% decrease relative to controls). Effect sizes were similar for higher doses (5mg/kg/d PFOA and 10mg/kg/d GenX) and lower doses (1mg/kg/d PFOA and 2mg/kg/d GenX), including higher maternal liver weights, changes in liver histopathology, higher placental weights and embryo-placenta weight ratios, and greater incidence of placental abnormalities relative to controls. Histopathological features in placentas suggested that PFOA and GenX may exhibit divergent mechanisms of toxicity in the embryo-placenta unit, whereas PFOA- and GenX-exposed livers shared a similar constellation of adverse pathological features.

CONCLUSIONS

Gestational exposure to GenX recapitulated many documented effects of PFOA in CD-1 mice, regardless of its much shorter reported half-life; however, adverse effects toward the placenta appear to have compound-specific signatures. https://doi.org/10.1289/EHP6233.

Δ9-tetrahydrocannabinol exposure during rat pregnancy leads to symmetrical fetal growth restriction and labyrinth-specific vascular defects in the placenta

1 in 5 women report cannabis use during pregnancy, with nausea cited as their primary motivation. Studies show that (-)-△9-tetrahydrocannabinol (Δ9-THC), the major psychoactive ingredient in cannabis, causes fetal growth restriction, though the mechanisms are not well understood. Given the critical role of the placenta to transfer oxygen and nutrients from mother, to the fetus, any compromise in the development of fetal-placental circulation significantly affects maternal-fetal exchange and thereby, fetal growth. The goal of this study was to examine, in rats, the impact of maternal Δ9-THC exposure on fetal development, neonatal outcomes, and placental development. Dams received a daily intraperitoneal injection (i.p.) of vehicle control or Δ9-THC (3 mg/kg) from embryonic (E)6.5 through 22. Dams were allowed to deliver normally to measure pregnancy and neonatal outcomes, with a subset sacrificed at E19.5 for placenta assessment via immunohistochemistry and qPCR. Gestational Δ9-THC exposure resulted in pups born with symmetrical fetal growth restriction, with catch up growth by post-natal day (PND)21. During pregnancy there were no changes to maternal food intake, maternal weight gain, litter size, or gestational length. E19.5 placentas from Δ9-THC-exposed pregnancies exhibited a phenotype characterized by increased labyrinth area, reduced Epcam expression (marker of labyrinth trophoblast progenitors), altered maternal blood space, decreased fetal capillary area and an increased recruitment of pericytes with greater collagen deposition, when compared to vehicle controls. Further, at E19.5 labyrinth trophoblast had reduced glucose transporter 1 (GLUT1) and glucocorticoid receptor (GR) expression in response to Δ9-THC exposure. In conclusion, maternal exposure to Δ9-THC effectively compromised fetal growth, which may be a result of the adversely affected labyrinth zone development. These findings implicate GLUT1 as a Δ9-THC target and provide a potential mechanism for the fetal growth restriction observed in women who use cannabis during pregnancy.

Expression of Retinoid Acid Receptor-Responsive Genes in Rodent Models of Placental Pathology

In humans, retinoic acid receptor responders (RARRES) have been shown to be altered in third trimester placentas complicated by the pathologies preeclampsia (PE) and PE with intrauterine growth restriction (IUGR). Currently, little is known about the role of placental Rarres in rodents. Therefore, we examined the localization and expression of Rarres1 and 2 in placentas obtained from a Wistar rat model of isocaloric maternal protein restriction (E18.5, IUGR-like features) and from an eNOS-knockout mouse model (E15 and E18.5, PE-like features). In both rodent models, Rarres1 and 2 were mainly localized in the placental spongiotrophoblast and giant cells. Their placental expression, as well as the expression of the Rarres2 receptor chemokine-like receptor 1 (CmklR1), was largely unaltered at the examined gestational ages in both animal models. Our results have shown that RARRES1 and 2 may have different expression and roles in human and rodent placentas, thereby underlining immanent limitations of comparative interspecies placentology. Further functional studies are required to elucidate the potential involvement of these proteins in early placentogenesis.

Plasmodium falciparum infection dysregulates placental autophagy

Plasmodium (P.) falciparum malaria during pregnancy has been frequently associated with severe consequences such as maternal anemia, abortion, premature birth, and reduced birth weight. Placental damage promotes disruption of the local homeostasis; though, the mechanisms underlying these events are still to be elucidated. Autophagy is a fundamental homeostatic mechanism in the natural course of pregnancy by which cells self-recycle in order to survive in stressful environments. Placentas from non-infected and P. falciparum-infected women during pregnancy were selected from a previous prospective cohort study conducted in the Brazilian Amazon (Acre, Brazil). Newborns from infected women experienced reduced birth weight (P = 0.0098) and placental immunopathology markers such as monocyte infiltrate (P < 0.0001) and IL-10 production (P = 0.0122). The placentas were evaluated for autophagy-related molecules. As a result, we observed reduced mRNA levels of ULK1 (P = 0.0255), BECN1 (P = 0.0019), and MAP1LC3B (P = 0.0086) genes in placentas from P. falciparum-infected, which was more striking in those diagnosed with placental malaria. Despite the protein levels of these genes followed the same pattern, the observed reduction was not statistically significant in placentas from P. falciparum-infected women. Nevertheless, our data suggest that chronic placental immunopathology due to P. falciparum infection leads to autophagy dysregulation, which might impair local homeostasis during malaria in pregnancy that may result in poor pregnancy outcomes.

Fetal growth outcomes following peri-implantation exposure of Long-Evans rats to noise and ozone differ by sex

Background

Exposure to air pollution and high levels of noise have both been independently associated with the development of adverse pregnancy outcomes including low birth weight. However, exposure to such environmental stressors rarely occurs in isolation and is often co-localized, especially in large urban areas.

Methods

The purpose of this study was to compare the effects of combined exposure to noise (N) or ozone (O₃), compared to either exposure alone. Long-Evans dams were exposed to air or 0.4 ppm ozone for 4 h on gestation day (GD) 5 and 6, coinciding with implantation receptivity. A subset of dams from each exposure group was further exposed to intermittent white noise (~ 85 dB) throughout the dark cycle following each inhalation exposure (n = 14 − 16/group). Uterine artery ultrasound was performed on GD 15 and 21. Fetal growth characteristics and indicators of placental nutrient status were measured at GD 21.

Results

Exposure to ozone + quiet (O₃ + Q) conditions reduced uterine arterial resistance at GD 15 compared to air + quiet (A + Q) exposure, with no further reduction by GD 21. By contrast, exposure to air + noise (A + N) significantly increased uterine arterial resistance at both GD 15 and 21. Notably, while peri-implantation exposure to O₃ + Q conditions reduced male fetal weight at GD 21, this effect was not observed in the air + noise (A + N) or the ozone + noise (O₃ + N) exposure groups. Fetal weight in female offspring was not reduced by ozone exposure alone (O₃ + Q), nor was it affected by air + noise (A + N) or by combined ozone + noise (O₃ + N) exposure.

Conclusions

These data indicate that exposure to ozone and noise differentially impact uterine blood flow, particularly at mid-gestation, with only ozone exposure being associated with sex-dependent fetal growth retardation in male offspring.

Sex-specific effects of leptin administration to pregnant mice on the placentae and the metabolic phenotypes of offspring

Obesity during pregnancy has been shown to increase the risk of metabolic diseases in the offspring. However, the factors within the maternal milieu which affect offspring phenotypes and the underlying mechanisms remain unknown. The adipocyte hormone leptin plays a key role in regulating energy homeostasis and is known to participate in sex‐specific developmental programming. To examine the action of leptin on fetal growth, placental gene expression and postnatal offspring metabolism, we injected C57BL mice with leptin or saline on gestational day 12 and then measured body weights (BWs) of offspring fed on a standard or obesogenic diet, as well as mRNA expression levels of insulin‐like growth factors and glucose and amino acid transporters. Male and female offspring born to leptin‐treated mothers exhibited growth retardation before and a growth surge after weaning. Mature male offspring, but not female offspring, exhibited increased BWs on a standard diet. Leptin administration prevented the development of hyperglycaemia in the obese offspring of both sexes. The placentas of the male and female foetuses differed in size and gene expression, and leptin injection decreased the fetal weights of both sexes, the placental weights of the male foetuses and placental gene expression of the GLUT1 glucose transporter in female foetuses. The data suggest that mid‐pregnancy is an ontogenetic window for the sex‐specific programming effects of leptin, and these effects may be exerted via fetal sex‐specific placental responses to leptin administration.

A Narrative Review of Placental Contribution to Adverse Pregnancy Outcomes in Women With Polycystic Ovary Syndrome

CONTEXT

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy of reproductive-aged women. In pregnancy, women with PCOS experience increased risk of miscarriage, gestational diabetes, preeclampsia, and extremes of fetal birth weight, and their offspring are predisposed to reproductive and cardiometabolic dysfunction in adulthood. Pregnancy complications, adverse fetal outcomes, and developmental programming of long-term health risks are known to have placental origins. These findings highlight the plausibility of placental compromise in pregnancies of women with PCOS.

EVIDENCE SYNTHESIS

A comprehensive PubMed search was performed using terms "polycystic ovary syndrome," "placenta," "developmental programming," "hyperandrogenism," "androgen excess," "insulin resistance," "hyperinsulinemia," "pregnancy," and "pregnancy complications" in both human and animal experimental models.

CONCLUSIONS

There is limited human placental research specific to pregnancy of women with PCOS. Gestational androgen excess and insulin resistance are two clinical hallmarks of PCOS that may contribute to placental dysfunction and underlie the higher rates of maternal-fetal complications observed in pregnancies of women with PCOS. Additional research is needed to prevent adverse maternal and developmental outcomes in women with PCOS and their offspring.

Subcutaneous maternal resveratrol treatment increases uterine artery blood flow in the pregnant ewe and increases fetal but not cardiac growth

KEY POINTS

Substrate restriction during critical developmental windows of gestation programmes offspring for a predisposition towards cardiovascular disease in adult life. This study aimed to determine the effect of maternal resveratrol (RSV) treatment in an animal model in which chronic fetal catheterisation is possible and the timing of organ maturation reflects that of the human. Maternal RSV treatment increased uterine artery blood flow, fetal oxygenation and fetal weight. RSV was not detectable in the fetal circulation, indicating that it may not cross the sheep placenta. This study highlights RSV as a possible intervention to restore fetal substrate supply in pregnancies affected by placental insufficiency.

ABSTRACT

Suboptimal in utero environments with reduced substrate supply during critical developmental windows of gestation predispose offspring to non-communicable diseases such as cardiovascular disease (CVD). Improving fetal substrate supply in these pregnancies may ameliorate the predisposition these offspring have toward adult-onset CVD. This study aimed to determine the effect of maternal resveratrol (RSV) supplementation on uterine artery blood flow and the direct effects of RSV on the fetal heart in a chronically catheterised sheep model of human pregnancy. Maternal RSV treatment significantly increased uterine artery blood flow as measured by phase contrast magnetic resonance imaging, mean gestational fetal P a O 2 and S a O 2 as well as fetal weight. RSV was not detectable in the fetal circulation, and mRNA and protein expression of the histone/protein deacetylase SIRT1 did not differ between treatment groups. No effect of maternal RSV supplementation on AKT/mTOR or CAMKII signalling in the fetal left ventricle was observed. Maternal RSV supplementation is capable of increasing fetal oxygenation and growth in an animal model in which cardiac development parallels that of the human.

Global population variation in placental size and structure: Evidence from Cebu, Philippines

INTRODUCTION

Placental morphology influences the intrauterine environment and fetal growth, which help set life-course health trajectories across generations. Little is known about placental characteristics in populations with chronic nutritional insufficiency where birth weights tend to be lower, and how these relationships between birth and placental weights vary across populations.

METHODS

We collected weights and stereologically-determined villous mass and surface area of 21 placentas from offspring of women enrolled in a birth cohort study in metropolitan Cebu, Philippines, a low-income population. We identified 15 samples from other global populations ranging from low to high income that had similar data to ours to assess patterns of variation between birth and placental weights and microscopic characteristics. We ranked the population samples in order for each characteristic.

RESULTS

Mean birth weight in Cebu was 3162 ± 80 g (ranked 9/16) and placental weight was 454 ± 32 g (ranked 12/16). Birth:placental weight ratio was 7.0 (ranked 3/16). Average villous surface area for Cebu placentas was 6.5 m2 (ranked 9/12); Birth weight:villous surface area was 0.048 g/m2 (ranked 4/12).

DISCUSSION

Placentas from Cebu produced heavier neonates per units of placental weight and villous surface area than most other populations, despite lower villous surface areas and less complex surface-to-volume topography. This range of placental efficiency spurs questions about the mechanisms by which placental morphology optimizes efficiency in different environmental contexts during gestation. Placental variation both within and across populations is likely due to many intersecting environmental, metabolic, and (epi)genetic factors that will require additional research to clarify.

Placental structure in gestational diabetes mellitus

The placenta is a transitory organ, located between the mother and the foetus, which supports intrauterine life. This organ has nutritional, endocrine and immunologic functions to support foetal development. Several factors are related to the correct functioning of the placenta including foetal and maternal blood flow, appropriate nutrients, expression and function of receptors and transporters, and the morphology of the placenta itself. Placental morphology is crucial for understanding the pathophysiology of the organ as represents the physical structure where nutrient exchange occurs. In pathologies of pregnancy such as diabetes mellitus in humans and animal models, several changes in the placental morphology occur, related mainly with placental size, hypervascularization, higher branching capillaries of the villi and increased glycogen deposits among others. Gestational diabetes mellitus is associated with modifications in the structure of the human placenta including changes in the surface area and volume, as well as histological changes including an increased volume of intervillous space and terminal villi, syncytiotrophoblast number, fibrinoid areas, and glycogen deposits. These modifications may result in functional changes in this organ thus limiting the wellbeing of the developing foetus. This review gives an overview of recurrent morphological changes at macroscopic and histological levels seen in the placenta from gestational diabetes in humans and animal models. This article is part of a Special Issue entitled: Membrane Transporters and Receptors in Pregnancy Metabolic Complications edited by Luis Sobrevia.

Pregnancy outcome in mothers over the age of 35

PURPOSE OF REVIEW

The proportion of pregnancies occurring in women of at least 35 years of age has increased from 6.2% in 1980 to 22.3% of births in 2016. This review summarizes recent epidemiological and basic scientific studies investigating the association between older maternal age and adverse pregnancy outcome(s), and clinical studies which investigate the effects of intervention to reduce adverse events.

RECENT FINDINGS

Women of at least 35 years of age have increased risk of maternal and foetal complications in pregnancy including: stillbirth, a small for gestational age baby, preterm birth, preeclampsia and maternal death. These risks increase with increasing age. The reasons for this increased risk are incompletely understood, but likely involve ageing of the maternal cardiovascular and endocrine systems which impacts upon placental function. Intervention, by induction of labour (IOL) at 39-week gestation does not increase operative deliveries or short-term adverse maternal and neonatal outcomes and would reduce perinatal mortality.

SUMMARY

The additional risks of pregnancy should be discussed with women of at least 35 years of age; additional foetal surveillance may be required in the antenatal period. The benefits and risks of IOL at 39-week gestation should be discussed with women at least 35 years of age.

Assessment of placental metal levels in a South African cohort

The placenta plays an important role in mediating the effect of maternal metal exposure on fetal development, acting as both barrier and transporter. Term-placenta metal levels serve as an informative snapshot of maternal/fetal exposure during pregnancy and could be used to predict offspring short- and long-term health outcomes. Here, we measured term-placenta metal levels of 11 metals in 42 placentas from the Soweto First 1000 days cohort (S1000, Soweto-Johannesburg, SA). We compared these placental metal concentrations with previously reported global cohort measurements to determine whether this cohort is at increased risk of exposure. Placental metals were tested for correlations to understand potential interactions between metals. Since these samples are from a birth cohort study, we also performed exploratory analyses to determine whether metal levels were associated with placenta and birth outcomes. Most S1000 placental metal levels were similar to other cohorts; however, cadmium (Cd) levels up to 50-fold lower, and essential elements nickel (Ni) and chromium (Cr) level up to 6- and 16-fold lower, respectively. Cd, Se, and Ni were associated with placenta and birth outcomes. Studies are ongoing to examine underlying mechanisms and how these developmental differences affect long-term health.

Epigenetically regulated imprinted gene expression associated with IVF and infertility: possible influence of prenatal stress and depression

PURPOSE

Despite the growing body of research implying an impact of in vitro fertilization (IVF) on imprinted genes and epigenetics, few studies have examined the effects of underlying subfertility or prenatal stress on epigenetics, particularly in terms of their role in determining infant birthweights. Both subfertility and prenatal stressors have been found to impact epigenetics and may be confounding the effect of IVF on epigenetics and imprinted genes. Like IVF, both of these exposures-infertility and prenatal stressors-have been associated with lower infant birthweights. The placenta, and specifically epigenetically regulated placental imprinted genes, provides an ideal but understudied mechanism for evaluating the relationship between underlying genetics, environmental exposures, and birthweight.

METHODS AND RESULTS

In this review, we discuss the impacts of IVF and infertility on birthweight, epigenetic mechanisms and genomic imprinting, and the role of these mechanisms in the IVF population and discuss the role and importance of the placenta in infant development. We then highlight recent work on the relationships between infertility, IVF, and prenatal stressors in terms of placental imprinting.

CONCLUSIONS

In combination, the studies discussed, as well as two recent projects of our own on placental imprinted gene expression, suggest that lower birthweights in IVF infants are secondary to a combination of exposures including the infertility and prenatal stress that couples undergoing IVF are experiencing. The work highlighted herein emphasizes the need for appropriate control populations that take infertility into account and also for consideration of prenatal psychosocial stressors as confounders and causes of variation in IVF infant outcomes.

Ergot alkaloid exposure during gestation alters. I. Maternal characteristics and placental development of pregnant ewes1

Tall fescue [Lolium arundinaceum (Scheyreb.) Darbysh] is the primary cool season forage grass in the Southeastern United States. Most tall fescue contains an endophytic fungus (Epichloë coenophiala) that produces ergot alkaloids and upon ingestion induces fescue toxicosis. The objective of this study was to assess how exposure to endophyte-infected (E+; 1.77 mg hd-1 d-1 ergovaline and ergovalinine) or endophyte-free (E-; 0 mg hd-1 d-1 ergovaline and ergovalinine) tall fescue seed fed during 2 stages of gestation (MID, days 35-85/LATE, days 86-133) alters placental development. Thirty-six, fescue naïve Suffolk ewes were randomly assigned to 1 of 4 fescue treatments: E-/E-, E-/E+, E+/E-, or E+/E+. Ewes were individually fed the same amount of E+ or E- seed mixed into total mixed ration during MID and LATE gestation. Terminal surgeries were conducted on day 133 of gestation. Ewes fed E+ fescue seed had elevated (P < 0.001) ergot alkaloid excretion and reduced (P < 0.001) prolactin levels during the periods when fed E+ seed. Ewes switched on day 86 from E- to E+ seed had a 4% reduction (P = 0.005) in DMI during LATE gestation, which translated to a 2% reduction (P = 0.07) in DMI overall. Average daily gain was also reduced (P = 0.049) by 64% for E-/E+ ewes during LATE gestation and tended to be reduced (P = 0.06) by 33% overall. Ewes fed E+ seed during LATE gestation exhibited a 14% and 23% reduction in uterine (P = 0.03) and placentome (P = 0.004) weights, respectively. Caruncle weights were also reduced by 28% (P = 0.003) for E-/E+ ewes compared with E-/E- and E+/E-. Ewes fed E+ seed during both MID and LATE gestation exhibited a 32% reduction in cotyledon (P = 0.01) weights, whereas ewes fed E+ seed only during MID gestation (E+/E-) had improved (P = 0.01) cotyledon weights. The percentage of type A placentomes tended to be greater (P = 0.08) for E+/E+ ewes compared with other treatments. Other placentome types (B, C, or D) did not differ (P > 0.05). Total fetal weight per ewe was reduced (P = 0.01) for ewes fed E+ seed during LATE gestation compared with E-; however, feeding E+ seed during MID gestation did not alter (P = 0.70) total fetal weight per ewe. These results suggest that exposure to ergot alkaloids during LATE (days 86-133) gestation has the greatest impact on placental development by reducing uterine and placentome weights. This, in turn, reduced total fetal weight per ewe by 15% in ewes fed E+ seed during LATE gestation (E-/E+ and E+/E+).

Advanced maternal age and the impact on maternal and offspring cardiovascular health

Delaying pregnancy, which is on the rise, may increase the risk of cardiovascular disease in both women and their children. The physiological mechanisms that lead to these effects are not fully understood but may involve inadequate adaptations of the maternal cardiovascular system to pregnancy. Indeed, there is abundant evidence in the literature that a fetus developing in a suboptimal in utero environment (such as in pregnancies complicated by fetal growth restriction, preterm birth, and/or preeclampsia) is at an increased risk of cardiovascular disease in adulthood, the developmental origins of health and disease theory. Although women of advanced age are at a significantly increased risk of pregnancy complications, there is limited information as to whether advanced maternal age constitutes an added stressor on the prenatal environment of the fetus, and whether or not this is secondary to impaired cardiovascular function during pregnancy. This review summarizes the current literature available on the impact of advanced maternal age on cardiovascular adaptations to pregnancy and the role of maternal age on long-term health risks for both the mother and offspring.

Fetal brain sparing in a mouse model of chronic maternal hypoxia

Hypoxic stress is a common occurrence during human pregnancy, yet little is known about its effects on the fetal brain. This study examined the fetal hemodynamic responses to chronic hypoxia in an experimental mouse model of chronic maternal hypoxia (11% O₂ from E14.5 to E17.5). Using high-frequency Doppler ultrasound, we found fetal cerebral and ductus venosus blood flow were both elevated by 69% and pulmonary blood flow was decreased by 62% in the fetuses exposed to chronic hypoxia compared to controls. This demonstrates that brain sparing persists during chronic fetal hypoxia and is mediated by "streaming," where highly oxygenated blood preferentially flows through the ductus venosus towards the cerebral circulation, bypassing the liver and the lungs. Consistent with these changes in blood flow, the fetal brain volume measured by MRI is preserved, while the liver and lung volumes decreased compared to controls. However, hypoxia exposed fetuses were rendered vulnerable to an acute hypoxic challenge (8% O₂ for 3 min), demonstrating global blood flow decreases consistent with imminent fetal demise rather than elevated cerebral blood flow. Despite this vulnerability, there were no differences in adult brain morphology in the mice exposed to chronic maternal hypoxia compared to controls.

Placental metal concentrations in relation to placental growth, efficiency and birth weight

The quality of the intrauterine environment, in which the placenta plays a critical role, affects birth outcomes and lifelong health. The effect of metal contaminants on the growth and functioning of the placenta have not been widely reported but may provide insights into how metal exposures lead to these outcomes. We examined relationships between placental concentrations of cadmium (Cd), arsenic (As), mercury (Hg) and lead (Pb) and measures of placental growth and functioning (placental weight, placental efficiency (the log ratio of placental weight and birth weight), chorionic disc area and disc eccentricity) as part of the New Hampshire Birth Cohort Study (N = 1159). We additionally examined whether these associations were modified by placental concentrations of essential elements zinc (Zn) and selenium (Se). Associations were evaluated using generalized linear models. Multivariable-adjusted differences in placental weight were - 7.81 g (95% CI: -15.42, -2.48) with every ng/g increase in the Cd concentration of placenta (p-Value = 0.0009). Greater decrements in placental weight and efficiency associated with placental Cd were observed for females. For placentae with below median Zn and Se concentrations, decrements in placental weight were - 8.81 g (95% CI: -16.85, -0.76) and - 13.20 g (95% CI: -20.70, -5.70) respectively. The Cd concentration of placenta was also associated with reductions in placental efficiency both overall, and in Zn- and Se-stratified models. No appreciable differences were observed with other elements (As, Hg or Pb) and with other placental measures (chorionic disc area and disc eccentricity). In structural equation models, placental weight was a mediator in the relation between placental Cd concentration and reduced birth weight. Our findings suggest a role of interacting essential and contaminant elements on birth weight that may be mediated by changes in the growth and function of the placenta.

The identification of differentially expressed genes between extremes of placental efficiency in maternal line gilts on day 95 of gestation

Background

Placental efficiency (PE) describes the relationship between placental and fetal weights (fetal wt/placental wt). Within litters, PE can vary drastically, resulting in similarly sized pigs associated with differently sized placentas, up to a 25% weight difference. However, the mechanisms enabling the smaller placenta to grow a comparable littermate are unknown. To elucidate potential mechanisms, morphological measurements and gene expression profiles in placental and associated endometrial tissues of high PE and low PE feto-placental units were compared. Tissue samples were obtained from eight maternal line gilts during gestational day 95 ovario-hysterectomies. RNA was extracted from tissues of feto-placental units with the highest and lowest PE in each litter and sequenced.

Results

Morphological measurements, except placental weight, were not different (P > 0.05) between high and low PE. No DEG were identified in the endometrium and 214 DEG were identified in the placenta (FDR < 0.1), of which 48% were upregulated and 52% were downregulated. Gene ontology (GO) analysis revealed that a large percentage of DEG were involved in catalytic activity, binding, transporter activity, metabolism, biological regulation, and localization. Four GO terms were enriched in the upregulated genes and no terms were enriched in the downregulated genes (FDR < 0.05). Eight statistically significant correlations (P < 0.05) were identified between the morphological measurements and DEG.

Conclusion

Morphological measures between high and low PE verified comparisons were of similarly sized pigs grown on different sized placentas, and indicated that any negative effects of a reduced placental size on fetal growth were not evident by day 95. The identification of DEG in the placenta, but absence of DEG in the endometrium confirmed that the placenta responds to the fetus. The GO analyses provided evidence that extremes of PE are differentially regulated, affecting components of placental transport capacity like nutrient transport and blood flow. However, alternative GO terms were identified, indicating the complexity of the relationship between placental and fetal weights. These findings support the use of PE as a marker of placental function and provide novel insight into the genetic control of PE, but further research is required to make PE production applicable.

TNFα is responsible for the canonical offspring number-size trade-off

There is a canonical life-history trade-off between quantity and quality of offspring, but molecular determinants for this are unknown. Here, we show that knockout of tumor necrosis factor (TNF-KO) in mice switched a relation between the number and size of developing embryos from expectedly negative to unexpectedly positive. Depletion of TNFα imbalanced humoral and trophic maintenance of embryo growth during gestation with respect to the litter size. The levels of embryotrophic GM-CSF cytokine and placental efficiency attained positive correlations with the number and size of embryos in TNF-KO females. Thus, TNFα oversees mother’s resource allocations to balance embryo growth with the number of offspring. Consequently, this suggests an intricate link between the number-size trade-off and immunity given a pivotal role of TNFα in immune homeostasis.

Placental weight in relation to maternal and paternal preconception and prenatal urinary phthalate metabolite concentrations among subfertile couples

INTRODUCTION

Phthalates are known reproductive toxicants that reduce placental and fetal weight in experimental animal studies. Although phthalate exposure has been associated with reduced birth weight in humans, there is limited epidemiologic evidence on whether the placenta is also affected.

OBJECTIVE

To assess whether maternal and paternal preconception and prenatal urinary phthalate metabolite concentrations are associated with placental weight, and the birth weight: placental weight (BW:PW) ratio among singletons conceived by subfertile couples.

METHODS

The present analysis included 132 mothers and 68 fathers, and their corresponding 132 singletons recruited in an academic hospital fertility center in Boston, Massachusetts. Urinary concentrations of eleven phthalate metabolites were measured and averaged in multiple paternal (n = 196) and maternal (n = 596) preconception, and maternal prenatal (n = 328) samples. Placental weight and birth weight (grams) were abstracted from delivery records, and the BW:PW was calculated. We estimated the association of natural log-phthalate metabolite concentrations across windows of exposure with placental weight and the BW:PW ratio using multivariable linear regression models, adjusting for a priori covariates.

RESULTS

In adjusted models, each log-unit increase in paternal urinary concentrations of the sum of di-(2-ethylhexyl) phthalate (ΣDEHP) metabolites was associated with a 24 g (95% CI: -48, -1) decrease in placental weight. We also observed a significant negative association between maternal preconception monoethyl phthalate (MEP) metabolite concentrations and the BW:PW ratio (β = -0.26; 95%CI: -0.49, -0.04). Additionally, each log-unit increase in prenatal MEP metabolite concentrations was associated with a 24 g (95% CI: -41, -7) decrease in placental weight.

CONCLUSIONS

Our results suggest that certain paternal and maternal urinary phthalate metabolites may affect placental weight and the BW:PW ratio. However, given the small sample size within a subfertile cohort and the novelty of these findings, more studies are needed to confirm the present results.

The Possible Role of Placental Morphometry in the Detection of Fetal Growth Restriction

Fetal growth restriction (FGR) is often the result of placental insufficiency and is characterized by insufficient transplacental transport of nutrients and oxygen. The main underlying entities of placental insufficiency, the pathophysiologic mechanism, can broadly be divided into impairments in blood flow and exchange capacity over the syncytiovascular membranes of the fetal placenta villi. Fetal growth restriction is not synonymous with small for gestational age and techniques to distinguish between both are needed. Placental insufficiency has significant associations with adverse pregnancy outcomes (perinatal mortality and morbidity). Even in apparently healthy survivors, altered fetal programming may lead to long-term neurodevelopmental and metabolic effects. Although the concept of fetal growth restriction is well appreciated in contemporary obstetrics, the appropriate detection of FGR remains an issue in clinical practice. Several approaches have aimed to improve detection, e.g., uniform definition of FGR, use of Doppler ultrasound profiles and use of growth trajectories by ultrasound fetal biometry. However, the role of placental morphometry (placental dimensions/shape and weight) deserves further exploration. This review article covers the clinical relevance of placental morphometry during pregnancy and at birth to help recognize fetuses who are growth restricted. The assessment has wide intra- and interindividual variability with various consequences. Previous studies have shown that a small placental surface area and low placental weight are associated with a slower growth of the fetus. Parameters such as placental surface area, placental volume and placental weight in relation to birth weight can help to identify FGR. In the future, a model including sophisticated antenatal placental morphometry may prove to be a clinically useful method for screening or diagnosing growth restricted fetuses, in order to provide optimal monitoring.

Placental transcriptional and histologic subtypes of normotensive fetal growth restriction are comparable to preeclampsia

BACKGROUND

Infants born small for gestational age because of pathologic placenta-mediated fetal growth restriction can be difficult to distinguish from those who are constitutionally small. Additionally, even among fetal growth-restricted pregnancies with evident placental disease, considerable heterogeneity in clinical outcomes and long-term consequences has been observed. Gene expression studies of fetal growth-restricted placentas also have limited consistency in their findings, which is likely due to the presence of different molecular subtypes of disease. In our previous study on preeclampsia, another heterogeneous placenta-centric disorder of pregnancy, we found that, by clustering placentas based only on their gene expression profiles, multiple subtypes of preeclampsia, including several with co-occurring suspected fetal growth restriction, could be identified.

OBJECTIVE

The purpose of this study was to discover placental subtypes of normotensive small-for-gestational-age pregnancies with suspected fetal growth restriction through the use of unsupervised clustering of placental gene expression data and to investigate their relationships with hypertensive suspected fetal growth-restricted placental subtypes.

STUDY DESIGN

A new dataset of 20 placentas from normotensive small-for-gestational-age pregnancies (birthweight <10th percentile for gestational age and sex) with suspected fetal growth restriction (ultrasound features of placental insufficiency) underwent genome-wide messenger RNA expression assessment and blinded detailed histopathologic evaluation. These samples were then combined with a subset of samples from our previously published preeclampsia cohort (n=77) to form an aggregate fetal growth-focused cohort (n=97) of placentas from normotensive small-for-gestational-age, hypertensive (preeclampsia and chronic hypertensive) small-for-gestational-age, and normotensive average-for-gestational-age pregnancies. Gene expression data were subjected to unsupervised clustering, and clinical and histopathologic features were correlated to the identified sample clusters.

RESULTS

Clustering of the aggregate dataset revealed 3 transcriptional subtypes of placentas from normotensive small-for-gestational-age/suspected fetal growth-restricted pregnancies, with differential enrichment of clinical and histopathologic findings. The first subtype exhibited either no placental disease or mild maternal vascular malperfusion lesions, and, co-clustered with the healthy average-for-gestational-age control subjects; the second subtype showed more severe evidence of hypoxic damage and lesions of maternal vascular malperfusion, and the third subtype demonstrated an immune/inflammatory response and histologic features of a maternal-fetal interface disturbance. Furthermore, all 3 of these normotensive small-for-gestational-age subtypes co-clustered with a group of placentas from hypertensive small-for-gestational-age pregnancies with more severe clinical outcomes, but very comparable transcriptional and histologic placental profiles.

CONCLUSION

Overall, this study provides evidence for at least 2 pathologic placental causes of normotensive small-for-gestational-age, likely representing true fetal growth restriction. These subtypes also show considerable similarity in gene expression and histopathology to our previously identified "canonical" and "immunologic" preeclampsia placental subtypes. Furthermore, we discovered a subtype of normotensive small-for-gestational-age (with suspected fetal growth restriction) with minimal placental disease that may represent both constitutionally small infants and mild fetal growth restriction, although these cannot be distinguished with the currently available data. Future work that focuses on the identification of etiology-driven biomarkers and therapeutic interventions for each subtype of fetal growth restriction is warranted.

Human sFLT1 Leads to Severe Changes in Placental Differentiation and Vascularization in a Transgenic hsFLT1/rtTA FGR Mouse Model

The anti-angiogenic soluble fms-like tyrosine kinase 1 (sFLT1) is one of the candidates in the progression of preeclampsia, often associated with fetal growth restriction (FGR). Therapeutic agents against preeclampsia with/without FGR, as well as adequate transgenic sFLT1 mouse models for testing such agents, are still missing. Much is known about sFLT1-mediated endothelial dysfunction in several tissues; however, the influence of sFLT1 on placental and fetal development is currently unknown. We hypothesize that sFLT1 is involved in the progression of FGR by influencing placental differentiation and vascularization and is a prime candidate for interventional strategies. Therefore, we generated transgenic inducible human sFLT1/reverse tetracycline-controlled transactivator (hsFLT1/rtTA) mice, in which hsFLT1 is ubiquitously overexpressed during pregnancy in dams and according to the genetics in hsFLT1/rtTA homozygous and heterozygous fetuses. Induction of hsFLT1 led to elevated hsFLT1 levels in the serum of dams and on mRNA level in all placentas and hetero-/homozygous fetuses, resulting in FGR in all fetuses at term. The strongest effects in respect to FGR were observed in the hsFLT1/rtTA homozygous fetuses, which exhibited the highest hsFLT1 levels. Only fetal hsFLT1 expression led to impaired placental morphology characterized by reduced placental efficiency, enlarged maternal sinusoids, reduced fetal capillaries, and impaired labyrinthine differentiation, associated with increased apoptosis. Besides impaired placental vascularization, the expression of several transporter systems, such as glucose transporter 1 and 3 (Glut-1; Glut-3); amino acid transporters, solute carrier family 38, member one and two (Slc38a1; Slc38a2); and most severely the fatty acid translocase Cd36 and fatty acid binding protein 3 (Fabp3) was reduced upon hsFLT1 expression, associated with an accumulation of phospholipids in the maternal serum. Moreover, the Vegf pathway showed alterations, resulting in reduced Vegf, Vegfb, and Plgf protein levels and increased Bad and Caspase 9 mRNA levels. We suggest that hsFLT1 exerts an inhibitory influence on placental vascularization by reducing Vegf signaling, which leads to apoptosis in fetal vessels, impairing placental differentiation, and the nutrient exchange function of the labyrinth. These effects were more pronounced when both the dam and the fetus expressed hsFLT1 and ultimately result in FGR and resemble the preeclamptic phenotype in humans.

Prenatal Exposure to Select Phthalates and Phenols and Associations with Fetal and Placental Weight among Male Births in the EDEN Cohort (France)

BACKGROUND

The placenta performs crucial physiological functions to ensure normal fetal development. Few epidemiological studies investigated placental weight sensitivity to phthalates and phenols.

OBJECTIVE

Our goal was to explore whether maternal exposure to select phthalates and phenols is associated with changes in placental weight at birth and in placental–to–birth weight ratio (PFR).

METHODS

Placental weight and birth weight were available for 473 mother–son pairs in the EDEN (Etude des Déterminants pré et postnatals du développement et de la santé de l'Enfant) cohort for whom 9 phenols (4 parabens, 2 dichlorophenols, triclosan, benzophenone-3, bisphenol A) and 11 phthalate metabolites were measured in spot urine samples collected between weeks 23 and 29 of gestation. We used adjusted Elastic Net penalized regression models (ENET) to select biomarkers associated with placental weight, birth weight and PFR. Unpenalized effect estimates were then obtained by fitting linear regression models simultaneously adjusted for the ENET-selected biomarkers and a priori chosen confounders.

RESULTS

The multipollutant ENET model for placental weight retained four biomarkers: triclosan and monocarboxy-isononyl phthalate (MCNP), which were negatively associated with placental weight, and benzophenone-3 and the sum of parabens, which were positively associated with this outcome. The ENET model for PFR retained two phthalate metabolites [MCNP and monocarboxy-isooctyl phthalate (MCOP)], which were negatively associated with this outcome.

DISCUSSION

The positive association between the sum of parabens and placental weight was consistent with results of a previous study among 49 male births. Our results provide preliminary evidence of possible associations between other compounds such as triclosan, benzophenone-3, MCNP, and MCOP and both placental weight and PFR. These associations were not reported in previous studies and should be seen as hypothesis generating. Studies relying on repeated assessments of exposure in prospective mother–child cohorts are needed to substantiate the plausibility of the hypotheses generated by our results. https://doi.org/10.1289/EHP3523.

Effects of Arachidonic and Docosohexahenoic Acid Supplementation during Gestation in Rats. Implication of Placental Oxidative Stress

Arachidonic and docosahexaenoic acids (ARA and DHA) are important during pregnancy. However, the effects of dietary supplementation on fetal growth and oxidative stress are inconclusive. We aimed to assess the effect of high ARA and DHA diet during rat gestation on: (1) ARA and DHA availability in plasma and placenta, (2) fetal growth, and (3) placental oxidative stress, analyzing the influence of sex. Experimental diet (ED) was prepared by substituting soybean oil in the control diet (CD) by a fungi/algae-based oil containing ARA and DHA (2:1). Rats were fed with CD or ED during gestation; plasma, placenta, and fetuses were obtained at gestational day 20. DHA, ARA, and their precursors were analyzed in maternal plasma and placenta by gas chromatography/mass spectrophotometry. Fetuses and placentas were weighed, the proportion of fetuses with intrauterine growth restriction (IUGR) determined, and placental lipid and protein oxidation analyzed. ED fetuses exhibited lower body weight compared to CD, being >40% IUGR; fetal weight negatively correlated with maternal plasma ARA, but not DHA. Only ED female placenta exhibited higher lipid and protein oxidation compared to its CD counterparts; lipid peroxidation is negatively associated with fetal weight. In conclusion, high ARA during gestation associates with IUGR, through placental oxidative stress, with females being more susceptible.

Reduced Uteroplacental Perfusion Pressure (RUPP) causes altered trophoblast differentiation and pericyte reduction in the mouse placenta labyrinth

This study characterized the effect of the reduced utero-placental perfusion pressure (RUPP) model of placental insufficiency on placental morphology and trophoblast differentiation at mid-late gestation (E14.5). Altered trophoblast proliferation, reduced syncytiotrophoblast gene expression, increased numbers of sinusoidal trophoblast giant cells, decreased Vegfa and decreased pericyte presence in the labyrinth were observed in addition to changes in maternal blood spaces, the fetal capillary network and reduced fetal weight. Further, the junctional zone was characterized by reduced spongiotrophoblast and glycogen trophoblast with increased trophoblast giant cells. Increased Hif-1α and TGF-β-3 in vivo with supporting hypoxia studies in trophoblast stem (TS) cells in vitro, support hypoxia as a contributing factor to the RUPP placenta phenotype. Together, this study identifies altered cell populations within the placenta that may contribute to the phenotype, and thus support the use of RUPP in the mouse as a model of placenta insufficiency. As such, this model in the mouse provides a valuable tool for understanding the phenotypes resulting from genetic manipulation of isolated cell populations to further understand the etiology of placenta insufficiency and fetal growth restriction. Further this study identifies a novel relationship between placental insufficiency and pericyte depletion in the labyrinth layer.