Fetal umbilical cord oxygen values and birth to placental weight ratio in relation to size at birth

Mortality and severe neurological morbidity in extremely preterm growth-restricted fetuses

OBJECTIVE

To develop a model for the prediction of adverse perinatal outcome in growth-restricted fetuses requiring delivery before 28 weeks in order to provide individualized patient counseling.

METHODS

This was a retrospective multicenter cohort study of singleton pregnancies with antenatal suspicion of fetal growth restriction requiring delivery before 28 weeks' gestation between January 2010 and January 2020 in six tertiary public hospitals in the Barcelona area, Spain. Separate predictive models for mortality only and mortality or severe neurological morbidity were created using logistic regression from variables available antenatally. For each model, predictive performance was evaluated using receiver-operating-characteristics (ROC)-curve analysis. Predictive models were validated externally in an additional cohort of growth-restricted fetuses from another public tertiary hospital with the same inclusion and exclusion criteria.

RESULTS

A total of 110 cases were included. The neonatal mortality rate was 37.3% and, among the survivors, the rate of severe neurological morbidity was 21.7%. The following factors were retained in the multivariate analysis as significant predictors of mortality: magnesium sulfate neuroprotection, gestational age at birth, estimated fetal weight, male sex and Doppler stage. This model had a significantly higher area under the ROC curve (AUC) compared with a model including only gestational age at birth (0.810 (95% CI, 0.730-0.889) vs 0.695 (95% CI, 0.594-0.795); P = 0.016). At a 20% false-positive rate, the model showed a sensitivity, negative predictive value and positive predictive value of 66%, 80% and 66%, respectively. For the prediction of the composite adverse outcome (mortality or severe neurological morbidity), the model included: gestational age at birth, male sex and Doppler stage. This model had a significantly higher AUC compared with a model including only gestational age at birth (0.810 (95% CI, 0.731-0.892) vs 0.689 (95% CI, 0.588-0.799); P = 0.017). At a 20% false-positive rate, the model showed a sensitivity, negative predictive value and positive predictive value of 55%, 63% and 74%, respectively. External validation of both models yielded similar AUCs that did not differ significantly from those obtained in the original sample.

CONCLUSIONS

Estimated fetal weight, fetal sex and Doppler stage can be combined with gestational age to improve the prediction of death or severe neurological sequelae in growth-restricted fetuses requiring delivery before 28 weeks. This approach may be useful for parental counseling and decision-making. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

The effect of maternal position on placental blood flow and fetoplacental oxygenation in late gestation fetal growth restriction: a magnetic resonance imaging study

Fetal growth restriction (FGR) and maternal supine going-to-sleep position are both risk factors for late stillbirth. This study aimed to use magnetic resonance imaging (MRI) to quantify the effect of maternal supine position on maternal-placental and fetoplacental blood flow, placental oxygen transfer and fetal oxygenation in FGR and healthy pregnancies. Twelve women with FGR and 27 women with healthy pregnancies at 34-38 weeks' gestation underwent MRI in both left lateral and supine positions. Phase-contrast MRI and a functional MRI technique (DECIDE) were used to measure blood flow in the maternal internal iliac arteries (IIAs) and umbilical vein (UV), placental oxygen transfer (placental flux), fetal oxygen saturation (FO2 ), and fetal oxygen delivery (delivery flux). The presence of FGR, compared to healthy pregnancies, was associated with a 7.8% lower FO2 (P = 0.02), reduced placental flux, and reduced delivery flux. Maternal supine positioning caused a 3.8% reduction in FO2 (P = 0.001), and significant reductions in total IIA flow, placental flux, UV flow and delivery flux compared to maternal left lateral position. The effect of maternal supine position on fetal oxygen delivery was independent of FGR pregnancy, meaning that supine positioning has an additive effect of reducing fetal oxygenation further in women with FGR, compared to women with appropriately grown for age pregnancies. Meanwhile, the effect of maternal supine positioning on placental oxygen transfer was not independent of the effect of FGR. Therefore, growth-restricted fetuses, which are chronically hypoxaemic, experience a relatively greater decline in oxygen transfer when mothers lie supine in late gestation compared to appropriately growing fetuses. KEY POINTS: Fetal growth restriction (FGR) is the most common risk factor associated with stillbirth, and early recognition and timely delivery is vital to reduce this risk. Maternal supine going-to-sleep position is found to increase the risk of late stillbirth but when combined with having a FGR pregnancy, maternal supine position leads to 15 times greater odds of stillbirth compared to supine sleeping with appropriately grown for age (AGA) pregnancies. Using MRI, this study quantifies the chronic hypoxaemia experienced by growth-restricted fetuses due to 13.5% lower placental oxygen transfer and 26% lower fetal oxygen delivery compared to AGA fetuses. With maternal supine positioning, there is a 23% reduction in maternal-placental blood flow and a further 14% reduction in fetal oxygen delivery for both FGR and AGA pregnancies, but this effect is proportionally greater for growth-restricted fetuses. This knowledge emphasises the importance of avoiding supine positioning in late pregnancy, particularly for vulnerable FGR pregnancies.

Neonatal outcomes following early fetal growth restriction: a subgroup analysis of the EVERREST study

OBJECTIVE

To quantify the risks of mortality, morbidity and postnatal characteristics associated with extreme preterm fetal growth restriction (EP-FGR).

DESIGN

The EVERREST (Do e s v ascular endothelial growth factor gene therapy saf e ly imp r ove outcome in seve r e e arly-onset fetal growth re st riction?) prospective multicentre study of women diagnosed with EP-FGR (singleton, estimated fetal weight (EFW) <3rd percentile, <600 g, 20+0-26+6 weeks of gestation). The UK subgroup of EP-FGR infants (<36 weeks) were sex-matched and gestation-matched to appropriate for age (AGA) infants born in University College London Hospital (1:2 design, EFW 25th-75th percentile).

SETTING

Four tertiary perinatal units (UK, Germany, Spain, Sweden).

MAIN OUTCOMES

Antenatal and postnatal mortality, bronchopulmonary dysplasia (BPD), sepsis, surgically treated necrotising enterocolitis (NEC), treated retinopathy of prematurity (ROP).

RESULTS

Of 135 mothers recruited with EP-FGR, 42 had a stillbirth or termination of pregnancy (31%) and 93 had live births (69%). Postnatal genetic abnormalities were identified in 7/93 (8%) live births. Mean gestational age at birth was 31.4 weeks (SD 4.6). 54 UK-born preterm EP-FGR infants (<36 weeks) were matched to AGA controls. EP-FGR was associated with increased BPD (43% vs 26%, OR 3.6, 95% CI 1.4 to 9.4, p=0.01), surgical NEC (6% vs 0%, p=0.036) and ROP treatment (11% vs 0%, p=0.001). Mortality was probably higher among FGR infants (9% vs 2%, OR 5.0, 95% CI 1.0 to 25.8, p=0.054). FGR infants more frequently received invasive ventilation (65% vs 50%, OR 2.6, 95% CI 1.1 to 6.1, p=0.03), took longer to achieve full feeds and had longer neonatal stays (median difference 6.1 days, 95% CI 3.8 to 8.9 and 19 days, 95% CI 9 to 30 days, respectively, p<0.0001).

CONCLUSIONS

Mortality following diagnosis of EP-FGR is high. Survivors experience increased neonatal morbidity compared with AGA preterm infants.

TRIAL REGISTRATION NUMBER

NCT02097667.

The impact of maternal diabetes on birth to placental weight ratio and umbilical cord oxygen values with implications for fetal-placental development

INTRODUCTION

We determined the impact of gestational diabetes (GDM) and pre-existing diabetes (DM) on birth/placental weight and cord oxygen values with implications for placental efficiency and fetal-placental growth and development.

METHODS

A hospital database was used to obtain birth/placental weight, cord PO₂ and other information on patients delivering between Jan 1, 1990 and Jun 15, 2011 with GA >34 weeks (N = 69,854). Oxygen saturation was calculated from the cord PO₂ and pH data, while fetal O₂ extraction was calculated from the oxygen saturation data. The effect of diabetic status on birth/placental weight and cord oxygen values was examined adjusting for covariates.

RESULTS

Birth/placental weights were stepwise decreased in GDM and DM compared to non-diabetics with placentas disproportionally larger indicating decreasing placental efficiency. Umbilical vein oxygen was marginally increased in GDM but decreased in DM attributed to the previously reported hyper-vascularization in diabetic placentas with absorbing surface area of capillaries initially increased, but then constrained by increasing distance from maternal blood within the intervillous space. Umbilical artery oxygen was unchanged in GDM and DM, with fetal O₂ extraction decreased in DM indicating that fetal O₂ delivery must be increased relative to O₂ consumption and likely due to increased umbilical blood flow.

DISCUSSION

Increased villous density/hyper-vascularization in GDM and DM with placentas disproportionately larger and umbilical blood flow increased, are postulated to normalize umbilical artery oxygen despite increased birth weights and growth-related O₂ consumption. These findings have implications for mechanisms signaling fetal-placental growth and development in diabetic pregnancies and differ from that reported with maternal obesity.

Impact of velamentous cord insertion on perinatal outcomes: a systematic review and meta-analysis

OBJECTIVE

Velamentous cord insertion may be identified prenatally, but the clinical implications of this diagnosis remain controversial. This meta-analysis aimed to quantitatively summarize current data on the association of velamentous cord insertion and adverse perinatal outcomes.

DATA SOURCES

A systematic search was performed in MEDLINE, Scopus, and the Cochrane Library from inception until May 22, 2022 to identify eligible studies.

STUDY ELIGIBILITY CRITERIA

Observational studies including singleton pregnancies with velamentous cord insertion, either prenatally or postnatally identified, and comparing them with those with central/eccentric cord insertion were considered eligible.

METHODS

The quality of the studies was assessed with the Newcastle-Ottawa scale and the risk of bias with the Quality In Prognosis Studies (QUIPS) tool. The main outcome was small-for-gestational-age neonates. Heterogeneity of the studies was evaluated using a Q test and an I² index. Analyses were performed using a random-effects model, with outcome data reported as relative risk or mean difference with 95% confidence interval.

RESULTS

In total, 9 cohort and 2 case-control studies, of which 4 had prenatal and 7 had postnatal velamentous cord insertion diagnosis, were included. The overall prevalence of velamentous cord insertion was estimated to be 1.4% among singleton pregnancies. Compared with the central/eccentric cord insertion control group, pregnancies with velamentous cord insertion were at higher risk of several adverse perinatal outcomes, namely small-for-gestational-age neonates (relative risk, 1.93; 95% confidence interval, 1.54-2.41), preeclampsia (relative risk, 1.85; 95% confidence interval, 1.01-3.39), pregnancy-induced hypertension (relative risk, 1.58; 95% confidence interval, 1.46-1.70), stillbirth (relative risk, 4.12; 95% confidence interval, 1.92-8.87), placental abruption (relative risk, 2.94; 95% confidence interval, 1.72-5.03), preterm delivery (relative risk, 2.14; 95% confidence interval, 1.73-2.65), emergency cesarean delivery (relative risk, 2.03; 95% confidence interval, 1.22-3.38), 1-minute Apgar score <7 (relative risk, 1.53; 95% confidence interval, 1.14-2.05), 5-minute Apgar score <7 (relative risk, 1.97; 95% confidence interval, 1.43-2.71), and neonatal intensive care unit admission (relative risk, 1.63; 95% confidence interval, 1.32-2.02). In a subgroup analysis, prenatally diagnosed velamentous cord insertion was associated with small-for-gestational-age neonates (relative risk, 1.66; 95% confidence interval, 1.19-2.32), stillbirth (relative risk, 4.78; 95% confidence interval, 1.42-16.08), and preterm delivery (relative risk, 2.69; 95% confidence interval, 2.01-3.60). In a sensitivity analysis of studies excluding cases with vasa previa, velamentous cord insertion was associated with an increased risk of small-for-gestational-age neonates (relative risk, 2.69; 95% confidence interval, 1.73-4.17), pregnancy-induced hypertension (relative risk, 1.94; 95% confidence interval, 1.24-3.01), and stillbirth (relative risk, 9.42; 95% confidence interval, 3.19-27.76), but not preterm delivery (relative risk, 1.92; 95% confidence interval, 0.82-4.54).

CONCLUSION

Velamentous cord insertion is associated with several adverse perinatal outcomes, including stillbirth, and these associations persist when only prenatally diagnosed cases are considered and when vasa previa cases are excluded. According to these findings, the exact pathophysiology should be further investigated and an effective prenatal monitoring plan should be developed.

Impact of marginal cord insertion on perinatal outcomes: a systematic review and meta-analysis

OBJECTIVE

Despite its high prevalence and the possible link with perinatal complications, marginal cord insertion is surrounded by considerable controversy regarding management. This meta-analysis aimed to study its association with several perinatal outcomes in a manner that provides trustworthy and exact effect measures, enabling us eventually to evaluate its overall risk for pregnancy.

DATA SOURCES

A systematic search was performed in Medline, Scopus, and the Cochrane Library on July 30, 2022, to identify eligible studies.

STUDY ELIGIBILITY CRITERIA

Observational studies, including singleton pregnancies and comparing MCI with central cord insertion or eccentric cord insertion, either prenatally or postnatally identified, were considered eligible.

METHODS

The Newcastle-Ottawa Scale was used to assess study quality, and the Quality in Prognosis Studies tool was used to assess bias risk. The main outcome was small-for-gestational-age neonates. A Q test and an I² score were used to assess study heterogeneity. The analyses were performed using a random-effects model, and the results were expressed as relative risk or mean difference with a 95% confidence interval.

RESULTS

Overall, 15 studies (13 cohort studies and 2 case-control studies) contributed data to the analysis. There was a prenatal diagnosis in 7 studies and a postnatal diagnosis in 8 studies. The overall prevalence of marginal cord insertion was 6.15% (range, 1.13%-11.3%). Pregnancies with marginal cord insertion compared with pregnancies with central cord insertion were found to be at higher risk of small-for-gestational-age neonates (relative risk, 1.25; 95% confidence interval, 1.21-1.29), preeclampsia (relative risk, 1.61; 95% confidence interval, 1.54-1.67), placental abruption (relative risk, 1.53; 95% confidence interval, 1.34-1.75), stillbirth (relative risk, 1.97; 95% confidence interval, 1.02-3.78), preterm delivery (relative risk, 1.47; 95% confidence interval, 1.24-1.75), lower mean gestational age at birth (mean difference, -0.20; 95% confidence interval, -0.38 to -0.01), emergency cesarean delivery (relative risk, 1.39; 95% confidence interval, 1.35-1.44), lower mean birthweight (mean difference, -139.19; 95% confidence interval, -185.78 to -92.61), 5-minute Apgar score of <7 (relative risk, 1.48; 95% confidence interval, 1.00-2.19), and neonatal intensive care unit admission (relative risk, 1.57; 95% confidence interval, 1.20-2.06). When only pregnancies with prenatally diagnosed MCI were considered, the risk remained high regarding small for gestational age (relative risk, 1.34; 95% confidence interval, 1.21-1.48), preeclampsia (relative risk, 1.42; 95% confidence interval, 1.01-1.99), stillbirth (relative risk, 2.99; 95% confidence interval, 1.03-8.70), preterm delivery (relative risk, 1.41; 95% confidence interval, 1.19-1.68), lower mean gestational age at birth (mean difference, -0.22; 95% confidence interval, -0.33 to -0.11), and lower mean birthweight (mean difference, -122.41; 95% confidence interval, -166.10 to -78.73).

CONCLUSION

Here, the higher risk that marginal cord insertion poses for pregnancy, regarding several adverse outcomes, became evident. Many of these associations persisted among the prenatally diagnosed pregnancies. The underlining pathophysiology should be investigated, and further research is needed on the effect of increased surveillance in improving perinatal outcomes.

Epigenetics Beyond Fetal Growth Restriction: A Comprehensive Overview

Fetal growth restriction is a pathological condition occurring when the fetus does not reach the genetically determined growth potential. The etiology of fetal growth restriction is expected to be multifactorial and include fetal, maternal, and placental factors, the latter being the most frequent cause of isolated fetal growth restriction. Severe fetal growth restriction has been related to both an increased risk of perinatal morbidity and mortality, and also a greater susceptibility to developing diseases (especially cardio-metabolic and neurological disorders) later in life. In the last decade, emerging evidence has supported the hypothesis of the Developmental Origin of Health and Disease, which states that individual developmental 'programming' takes place via a delicate fine tuning of fetal genetic and epigenetic marks in response to a large variety of 'stressor' exposures during pregnancy. As the placenta is the maternal-fetal interface, it has a crucial role in fetal programming, such that any perturbation altering placental function interferes with both in-utero fetal growth and also with the adult life phenotype. Several epigenetic mechanisms have been highlighted in modulating the dynamic placental epigenome, including alterations in DNA methylation status, post-translational modification of histones, and non-coding RNAs. This review aims to provide a comprehensive and critical overview of the available literature on the epigenetic background of fetal growth restriction. A targeted research strategy was performed using PubMed, MEDLINE, Embase, and The Cochrane Library up to January 2022. A detailed and fully referenced synthesis of available literature following the Scale for the Assessment of Narrative Review Articles guidelines is provided. A variety of epigenetic marks predominantly interfering with placental development, function, and metabolism were found to be potentially associated with fetal growth restriction. Available evidence on the role of environmental exposures in shaping the placental epigenome and the fetal phenotype were also critically discussed. Because of the highly dynamic crosstalk between epigenetic mechanisms and the extra level of complexity in interpreting the final placental transcriptome, a full comprehension of these phenomenon is still lacking and advances in multi-omics approaches are urgently needed. Elucidating the role of epigenetics in the developmental origins of health and disease represents a new challenge for the coming years, with the goal of providing early interventions and prevention strategies and, hopefully, new treatment opportunities.

Fetal sex impacts birth to placental weight ratio and umbilical cord oxygen values with implications for regulatory mechanisms

Background

We determined the effect of fetal sex on birth/placental weight and umbilical vein and artery oxygen values with implications for placental efficiency and regulatory mechanisms underlying fetal–placental growth differences.

Methods

A hospital database was used to obtain birth/placental weight, cord PO₂ and other information on patients delivering between Jan 1, 1990 and Jun 15, 2011 with GA > 34 weeks (N = 69,836). Oxygen saturation was calculated from the cord PO₂ and pH data, while fractional O₂ extraction was calculated from the oxygen saturation data. The effect of fetal sex on birth/placental weight, cord PO₂, O₂ saturation, and fractional O₂ extraction was examined in all patients adjusting for pregnancy and labor/delivery covariates, and in a subset of low-risk patients.

Results

Birth/placental weights were lower in females indicating decreased placental efficiency. Umbilical vein oxygen values were higher in females attributed to increased uterine blood flow, while artery oxygen values were lower in females attributed to decreased hemoglobin and umbilical blood flow, and increased oxygen consumption. Fetal O₂ extraction was increased in females confirming increased O₂ consumption relative to delivery.

Conclusions

Sex-related differences in uterine/umbilical blood flows, placental development, and fetal O₂ consumption can be linked to the differences observed in cord oxygen. The lower umbilical artery oxygen in females as a measure of systemic oxygenation signaling growth could account for their decreased birth weights, while slower development in female placentae could account for their lower placental weights, which could be differentially effected contributing to their lower birth/placental weights.

Birth/placental wt is decreased in females as a measure of placental efficiency.

Cord vein O₂ is increased in females as a measure of placental O₂ transport.

Cord artery O₂ is decreased in females as a measure of fetal systemic O₂ levels.

Sex differences in placental development link to cord O₂-birth/placental wt findings.

Human placental microperfusion and microstructural assessment by intra-voxel incoherent motion MRI for discriminating intrauterine growth restriction: a pilot study

OBJECTIVES

To evaluate the potential of Intravoxel Incoherent Motion (IVIM) Imaging in the quantification of placental micro-perfusion and microstructural features to identify and discriminate different forms of intrauterine growth restriction (IUGR) and normal fetuses pregnancies.

METHODS

Small for gestational age SGA (n = 8), fetal growth restriction FGR (n = 10), and normal (n = 49) pregnancies were included in the study. Placental Magnetic Resonance Imaging (MRI) was performed at 1.5 T using a diffusion-weighted sequence with 10 b-values. IVIM fractional perfusion (fp), diffusion (D), and pseudodiffusion (D*) were evaluated on the fetal and maternal placental sides. Correlations between IVIM parameters, Gestational Age (GA), Birth Weight (BW), and the presence or absence of prenatal fetoplacental Doppler abnormalities at the US were investigated in SGA, FGR, and normal placentae.

RESULTS

fp and D* of the placental fetal side discriminate between SGA and FGR (p = .021; p = .036, respectively), showing lower values in FGR. SGA showed an intermediate perfusion pattern in terms of fp and D* compared to FGR and normal controls. In the intrauterine growth restriction group (SGA + FGR), a significant positive correlation was found between fp and BW (p < .002) in the fetal placenta and a significant negative correlation was found between D and GA in both the fetal (p < .0009) and maternal (p < .006) placentas.

CONCLUSIONS

Perfusion IVIM parameters fp and D* may be useful to discriminate different micro-vascularization patterns in IUGR being helpful to detect microvascular subtle impairment even in fetuses without any sign of US Doppler impairment in utero. Moreover, fp may predict fetuses' body weight in intrauterine growth restriction pregnancies. The diffusion IVIM parameter D may reflect more rapid microstructural rearrangement of the placenta due to aging processes in the IUGR group than in normal controls.

Gestational age impacts birth to placental weight ratio and umbilical cord oxygen values with implications for the fetal oxygen margin of safety

BACKGROUND

We determined the impact of gestational age (GA) from near term to term to post-term on birth/placental weight ratio and cord oxygen values with implications for placental transport efficiency for oxygen, fetal O₂ consumption relative to delivery or fractional O₂ extraction, and oxygen margin of safety.

MATERIALS AND METHODS

A hospital database was used to obtain birth/placental weight ratios, cord PO₂ and other information on patients delivering between Jan 1, 1990 and Jun 15, 2011 with GA > 34 completed weeks (N = 69,852). Oxygen saturation was calculated from the cord PO₂ and pH data, while fractional O₂ extraction was calculated from the oxygen saturation data. The effect of GA grouping on birth/placental weight ratio, cord PO₂, O₂ saturation, and fractional O₂ extraction values, was examined in all patients adjusting for pregnancy and labor/delivery covariates, and in a subset of low-risk patients.

RESULTS

Birth/placental weight ratio and umbilical venous O₂ values increased with advancing GA, supporting the conjecture of increasing placental transport efficiency for oxygen. However, umbilical arterial O₂ values decreased while fractional O₂ extraction increased with successive GA groupings, indicating that fetal O₂ consumption must be increasing relative to delivery.

CONCLUSIONS

Fetal O₂ consumption can be seen as ever 'outgrowing' O₂ delivery over the last weeks of pregnancy and leading to a continued lowering in systemic oxygen levels. While this lowering in oxygen may trigger feedback mechanisms with survival benefit, the 'oxygen margin of safety' will also be lowered increasing perinatal morbidity and mortality which appear to be hypoxia related.

Cardiovascular fetal-to-neonatal transition: an in silico model

BACKGROUND

Previous models describing the fetal-to-neonatal transition often lack oxygen saturation levels, homeostatic control mechanisms, phasic hemodynamic signals, or describe the heart with a time-varying elastance model.

METHODS

We incorporated these elements in the adapted CircAdapt model with the one-fiber model for myocardial contraction, to simulate the hemodynamics of the healthy term human fetal circulation and its transition during the first 24 h after birth. The fetal-to-neonatal model was controlled by a time- and event-based script of changes occurring at birth, such as lung aeration and umbilical cord clamping. Model parameters were based on and validated with human and animal data.

RESULTS

The fetal circulation showed low pulmonary blood flow, right ventricular dominance, and inverted mitral and tricuspid flow velocity patterns, as well as high mean ductus venosus flow velocity. The neonatal circulation showed oxygen saturation levels to gradually increase to 98% in the first 15 min after birth as well as temporary left ventricular volume overload.

CONCLUSIONS

Hemodynamics of the term fetus and 24-h-old neonate, as well as the events occurring directly after birth and the transition during the first 24 h after birth, were realistically represented, allowing the model to be used for educational purposes and future research.

IMPACT

With the addition of oxygen saturation levels, homeostatic pressure-flow control mechanisms, and the one-fiber model for myocardial contraction, a new closed-loop cardiovascular model was constructed to give more insight into the healthy term human fetal circulation and its cardiovascular transition during the first 24 h after birth. Extensive validation confirmed that the hemodynamics of the term fetus and the fetal-to-neonatal transition were realistically represented with the model. This well-validated and versatile model can serve as an education as well as a research platform for in silico investigation of fetal-to-neonatal hemodynamic changes under a wide range of physiological and pathophysiological conditions.

Going Up Inflame: Reviewing the Underexplored Role of Inflammatory Programming in Stress-Induced Intrauterine Growth Restricted Livestock

The impact of intrauterine growth restriction (IUGR) on health in humans is well-recognized. It is the second leading cause of perinatal mortality worldwide, and it is associated with deficits in metabolism and muscle growth that increase lifelong risk for hypertension, obesity, hyperlipidemia, and type 2 diabetes. Comparatively, the barrier that IUGR imposes on livestock production is less recognized by the industry. Meat animals born with low birthweight due to IUGR are beset with greater early death loss, inefficient growth, and reduced carcass merit. These animals exhibit poor feed-to-gain ratios, less lean mass, and greater fat deposition, which increase production costs and decrease value. Ultimately, this reduces the amount of meat produced by each animal and threatens the economic sustainability of livestock industries. Intrauterine growth restriction is most commonly the result of fetal programming responses to placental insufficiency, but the exact mechanisms by which this occurs are not well-understood. In uncompromised pregnancies, inflammatory cytokines are produced at modest rates by placental and fetal tissues and play an important role in fetal development. However, unfavorable intrauterine conditions can cause cytokine activity to be excessive during critical windows of fetal development. Our recent evidence indicates that this impacts developmental programming of muscle growth and metabolism and contributes to the IUGR phenotype. In this review, we outline the role of inflammatory cytokine activity in the development of normal and IUGR phenotypes. We also highlight the contributions of sheep and other animal models in identifying mechanisms for IUGR pathologies.

Prediction of late-onset fetal growth restriction using a combined first- and second-trimester screening model

BACKGROUND

Prediction models for early fetal growth restriction (FGR) have been exhibited in many researches. However, prediction models for late FGR are limited. Late-onset FGR is easy to miss clinically because of its insidious onset. This study aimed to develop a simple combined first- and second-trimester prediction model for screening late-onset FGR in fetuses.

METHODS

This retrospective study included 2746 women who had singleton pregnancies and received routine ultrasound scans as training dataset. Late FGR is that diagnosed >32 weeks. Multivariate logistic regression was used to develop a prediction model.

RESULTS

One hundred and twenty-nine fetuses were identified as late-onset FGR. The significant predictors for late-onset FGR were maternal height, weight, and medical history; the first-trimester mean arterial pressure, the second-trimester head circumference/ abdominal circumference ratio; and the second-trimester estimated fetal weight. This model achieved a detection rate (DR........) of 51.6% for late-onset FGR at a 10% false positive rate (FPR) (area under the curve (AUC): 0.80, 95%CI 0.76-0.84).

CONCLUSIONS

A multivariate model combining first- and second-trimester default tests can detect 51.6% of cases of late-onset FGR at a 10% FPR. Further studies with more screening markers are needed to improve the detection rate.

Uteroplacental nutrient flux and evidence for metabolic reprogramming during sustained hypoxemia

Gestational hypoxemia is often associated with reduced birth weight, yet how hypoxemia controls uteroplacental nutrient metabolism and supply to the fetus is unclear. This study tested the effects of maternal hypoxemia (HOX) between 0.8 and 0.9 gestation on uteroplacental nutrient metabolism and flux to the fetus in pregnant sheep. Despite hypoxemia, uteroplacental and fetal oxygen utilization and net glucose and lactate uptake rates were similar in HOX (n = 11) compared to CON (n = 7) groups. HOX fetuses had increased lactate and pyruvate concentrations and increased net pyruvate output to the utero-placenta. In the HOX group, uteroplacental flux of alanine to the fetus was decreased, as was glutamate flux from the fetus. HOX fetuses had increased alanine and decreased aspartate, serine, and glutamate concentrations. In HOX placental tissue, we identified hypoxic responses that should increase mitochondrial efficiency (decreased SDHB, increased COX4I2) and increase lactate production from pyruvate (increased LDHA protein and LDH activity, decreased LDHB and MPC2), both resembling metabolic reprogramming, but with evidence for decreased (PFK1, PKM2), rather than increased, glycolysis and AMPK phosphorylation. This supports a fetal-uteroplacental shuttle during sustained hypoxemia whereby uteroplacental tissues produce lactate as fuel for the fetus using pyruvate released from the fetus, rather than pyruvate produced from glucose in the placenta, given the absence of increased uteroplacental glucose uptake and glycolytic gene activation. Together, these results provide new mechanisms for how hypoxemia, independent of AMPK activation, regulates uteroplacental metabolism and nutrient allocation to the fetus, which allow the fetus to defend its oxidative metabolism and growth.

Establishment of an in vitro placental barrier model cultured under physiologically relevant oxygen levels

The human placental barrier facilitates many key functions during pregnancy, most notably the exchange of all substances between the mother and fetus. However, preclinical models of the placental barrier often lacked the multiple cell layers, syncytialization of the trophoblast cells and the low oxygen levels that are present within the body. Therefore, we aimed to design and develop an in vitro model of the placental barrier that would reinstate these factors and enable improved investigations of barrier function. BeWo placental trophoblastic cells and human umbilical vein endothelial cells were co-cultured on contralateral sides of an extracellular matrix-coated transwell insert to establish a multilayered barrier. Epidermal growth factor and forskolin led to significantly increased multi-nucleation of the BeWo cell layer and increased biochemical markers of syncytial fusion, for example syncytin-1 and hCGβ. Our in vitro placental barrier possessed size-specific permeability, with 4000-Da molecules experiencing greater transport and a lower apparent permeability coefficient than 70 000-Da molecules. We further demonstrated that the BeWo layer had greater resistance to smaller molecules compared to the endothelial layer. Chronic, physiologically low oxygen exposure (3-8%) increased the expression of hypoxia-inducible factor 1α and syncytin-1, further increased multi-nucleation of the BeWo cell layer and decreased barrier permeability only against smaller molecules (457 Da/4000 Da). In conclusion, we built a novel in vitro co-culture model of the placental barrier that possessed size-specific permeability and could function under physiologically low oxygen levels. Importantly, this will enable future researchers to better study the maternal-fetal transport of nutrients and drugs during pregnancy.

Can a Difference in Gestational Age According to Biparietal Diameter and Abdominal Circumference Predict Intrapartum Placental Abruption?

This study aimed to investigate whether a difference in gestational age according to biparietal diameter (BPD) and abdominal circumference (AC) could be a clinically useful predictor of placental abruption during the intrapartum period. This retrospective cohort study was based on singletons who were delivered after 32 + 0 weeks between July 2015 and July 2020. We only included cases with at least two antepartum sonographies available within 4 weeks of delivery (n = 2790). We divided the study population into two groups according to the presence or absence of placental abruption and compared the clinical variables. The incidence of placental abruption was 2.0% (56/2790) and was associated with an older maternal age, a higher rate of preeclampsia, and being small for the gestational age. A difference of >2 weeks in gestational age according to BPD and AC occurred at a higher rate in the placental abruption group compared to the no abruption group (>2 weeks, 21.4% (12/56) vs. 7.5% (205/2734), p < 0.001; >3 weeks, 12.5% (7/56) vs. 2.0% (56/2734), p < 0.001). Logistic regression analysis revealed that the differences of >2 weeks and >3 weeks were both independent risk factors for placental abruption (odds ratio (OR) (95% confidence interval), 2.289 (1.140-4.600) and 3.918 (1.517-9.771), respectively) after adjusting for maternal age, preeclampsia, and small for gestational age births. We identified that a difference in gestational age of >2 weeks between BPD and AC could be an independent predictor of placental abruption.

Enhanced Nitrite-Mediated Relaxation of Placental Blood Vessels Exposed to Hypoxia Is Preserved in Pregnancies Complicated by Fetal Growth Restriction

Nitric oxide (NO) is essential in the control of fetoplacental vascular tone, maintaining a high flow-low resistance circulation that favors oxygen and nutrient delivery to the fetus. Reduced fetoplacental blood flow is associated with pregnancy complications and is one of the major causes of fetal growth restriction (FGR). The reduction of dietary nitrate to nitrite and subsequently NO may provide an alternative source of NO in vivo. We have previously shown that nitrite induces vasorelaxation in placental blood vessels from normal pregnancies, and that this effect is enhanced under conditions of hypoxia. Herein, we aimed to determine whether nitrite could also act as a vasodilator in FGR. Using wire myography, vasorelaxant effects of nitrite were assessed on pre-constricted chorionic plate arteries (CPAs) and veins (CPVs) from normal and FGR pregnancies under normoxic and hypoxic conditions. Responses to the NO donor, sodium nitroprusside (SNP), were assessed in parallel. Nitrate and nitrite concentrations were measured in fetal plasma. Hypoxia significantly enhanced vasorelaxation to nitrite in FGR CPAs (p < 0.001), and in both normal (p < 0.001) and FGR (p < 0.01) CPVs. Vasorelaxation to SNP was also potentiated by hypoxia in both normal (p < 0.0001) and FGR (p < 0.01) CPVs. However, compared to vessels from normal pregnancies, CPVs from FGR pregnancies showed significantly lower reactivity to SNP (p < 0.01). Fetal plasma concentrations of nitrate and nitrite were not different between normal and FGR pregnancies. Together, these data show that nitrite-mediated vasorelaxation is preserved in FGR, suggesting that interventions targeting this pathway have the potential to improve fetoplacental blood flow in FGR pregnancies.

Molecular Pathways of Cellular Senescence and Placental Aging in Late Fetal Growth Restriction and Stillbirth

Abnormally accelerated, premature placental senescence plays a crucial role in the genesis of pregnancy pathologies. Abnormal growth in the third trimester can present as small for gestational age fetuses or fetal growth restriction. One differs from the other by the presence of signs of placental insufficiency and the risk of stillbirth. The majority of stillbirths occur in normally grown fetuses and are classified as "unexplained", which often leads to conclusions that they were unpreventable. The main characteristic of aging is a gradual decline in the function of cells, tissues, and organs. These changes result in the accumulation of senescent cells in mitotic tissues. These cells begin the aging process that disrupts tissues' normal functions by affecting neighboring cells, degrading the extracellular matrix, and reducing tissues' regeneration capacity. Different degrees of abnormal placentation result in the severity of fetal growth restriction and its sequelae, including fetal death. This review aims to present the current knowledge and identify future research directions to understand better placental aging in late fetal growth restriction and unexplained stillbirth. We hypothesized that the final diagnosis of placental insufficiency can be made only using markers of placental senescence.

Salmonella Enteritidis foodborne infection induces altered placental morphometrics in the murine model

INTRODUCTION

Salmonella foodborne disease during pregnancy causes a significant fetal loss in domestic livestock and preterm birth, chorioamnionitis and miscarriage in humans. These complications could be associated with alterations in placental structure. This study was aimed to determine how a low dose of Salmonella Enteritidis during late gestation affects placental histomorphometric in mice.

METHODS

We used a self-limiting enterocolitis murine model. BALB/c pregnant animals received a low dose of Salmonella Enteritidis (3-4 x 10² CFU/mouse) on gestational day (GD) 15. At day 3 post infection bacterial loads, serum cytokines expression and placental histomorphometrics parameters were analyzed.

RESULTS

We found that a sub-lethal infection with Salmonella induced a significant drop in fetal weight -to-placental weight-ratio and an increase in the placental coefficient. After bacterial inoculation maternal organs were colonized, inducing placental morphometric alterations, including increased placental thickness, reduced surface area, and diminished major and minor diameters. Also, foci of necrosis accompanied by acute leukocyte infiltration in decidual zone, reduction of vascular spaces and vascular congestion in labyrinth zone, were also evident in placentas from infected females on GD 18. Our data shows that placentas from infected mothers are phenotypically different from control ones. Furthermore, expression of IFN-gamma and IL-6 was up regulated in response to Salmonella in maternal serum.

DISCUSSION

Our findings demonstrate that a low dose of Salmonella during late gestation alters the placental morphometry leading to negative consequences on pregnancy outcome such as significant reduction in fetal body weight.

Non-invasive monitoring of pH and oxygen using miniaturized electrochemical sensors in an animal model of acute hypoxia

Background

One of the most prevalent causes of fetal hypoxia leading to stillbirth is placental insufficiency. Hemodynamic changes evaluated with Doppler ultrasound have been used as a surrogate marker of fetal hypoxia. However, Doppler evaluation cannot be performed continuously. As a first step, the present work aimed to evaluate the performance of miniaturized electrochemical sensors in the continuous monitoring of oxygen and pH changes in a model of acute hypoxia-acidosis.

Methods

pH and oxygen electrochemical sensors were evaluated in a ventilatory hypoxia rabbit model. The ventilator hypoxia protocol included 3 differential phases: basal (100% FiO₂), the hypoxia-acidosis period (10% FiO₂) and recovery (100% FiO₂). Sensors were tested in blood tissue (ex vivo sensing) and in muscular tissue (in vivo sensing). pH electrochemical and oxygen sensors were evaluated on the day of insertion (short-term evaluation) and pH electrochemical sensors were also tested after 5 days of insertion (long-term evaluation). pH and oxygen sensing were registered throughout the ventilatory hypoxia protocol (basal, hypoxia-acidosis, and recovery) and were compared with blood gas metabolites results from carotid artery catheterization (obtained with the EPOC blood analyzer). Finally, histological assessment was performed on the sensor insertion site. One-way ANOVA was used for the analysis of the evolution of acid-based metabolites and electrochemical sensor signaling results; a t-test was used for pre- and post-calibration analyses; and chi-square analyses for categorical variables.

Results

At the short-term evaluation, both the pH and oxygen electrochemical sensors distinguished the basal and hypoxia-acidosis periods in both the in vivo and ex vivo sensing. However, only the ex vivo sensing detected the recovery period. In the long-term evaluation, the pH electrochemical sensor signal seemed to lose sensibility. Finally, histological assessment revealed no signs of alteration on the day of evaluation (short-term), whereas in the long-term evaluation a sub-acute inflammatory reaction adjacent to the implantation site was detected.

Conclusions

Miniaturized electrochemical sensors represent a new generation of tools for the continuous monitoring of hypoxia-acidosis, which is especially indicated in high-risk pregnancies. Further studies including more tissue-compatible material would be required in order to improve long-term electrochemical sensing.

Intrapartum Doppler ultrasound: where are we now?

Intrapartum hypoxic events most commonly occur in low-risk pregnancies with appropriately grown fetuses. Continuous intrapartum monitoring by means of cardiotocography has not demonstrated a reduction in the frequency of adverse perinatal outcome but has been linked with an increase in the caesarean section rate, particularly among women considered at low risk. Available data from the literature suggests that abnormalities in the uterine artery Doppler and in the ratio between fetal cerebral and umbilical Doppler (i.e. cerebroplacental ratio [CPR]) are associated with conditions of subclinical placental function occurring in fetuses who have failed to achieve their growth potential regardless of their actual size. In this review we summarize the available evidence on the use of intrapartum Doppler ultrasound for the fetal surveillance during labor and the identification of the fetuses at risk of intrapartum distress.

The Significance of True Knot of the Umbilical Cord in Long-Term Offspring Neurological Health

We aimed to study both the short- and long-term neurological implications in offspring born with confirmed knotting of the umbilical cord-"true knot of cord". In this population based cohort study, a comparison of perinatal outcome and long-term neurological hospitalizations was performed on the basis of presence or absence of true knot of cord. A Kaplan-Meier survival curve was constructed to compare the cumulative incidence of neurological hospitalizations between the study groups. Multivariable regression models were used to assess the independent association between true knot of cord, perinatal mortality and long term neurological related hospitalizations, while controlling for potential confounders. The study included 243,639 newborns, of them 1.1% (n = 2606) were diagnosed with true knot of the umbilical cord. Higher rates of intrauterine fetal demise (IUFD) were noted in the exposed group, a finding which remained significant in the multivariable generalized estimation equation, while controlling for confounders. The cumulative incidences of neurological hospitalizations over time were comparable between the groups. The Cox regression confirmed a lack of association between true knot of cord and total long term neurological related hospitalizations. While presence of true knot of the umbilical cord is associated with higher IUFD rates, in our population, however, its presence does not appear to impact the long term neurological health of exposed offspring.

Effect of prenatal nutritional intervention on foetal growth restriction: a real-world study in Shenzhen, China

Objective: Fetal growth restriction (FGR) is the primary cause of infant morbidity and mortality. Although nutritional intervention is generally used to cure FGR, its effects on early- and late-onset FGR have not been reported. This study aimed to resolve this issue in a real-world setting.Study design: We collected the data of pregnant women whose fetuses were diagnosed with FGR and subsequently born at Nanshan Women and Children's Care Hospital in Shenzhen, China. We conducted a MANOVA and series of Cox regression analyses to evaluate the effects of a prenatal nutritional intervention on early and late FGR after adjusting for potential confounders.Results: Our results demonstrated that the average birth weights in the four sub-intervention groups were 50.36-160.05 g higher than those in the nonintervention group. These differences were insignificant with respect to early-onset FGR. In late-onset FGR, however, the interventions led to birth weight increases of 164.95-244.45 g greater than those in the nonintervention group, and these differences were significant. During early-onset FGR, four different nutritional interventions reduced the incidence of small-for-gestational age by 8.00-13.76% relative to the incidence in the nonintervention group, while in late-onset FGR, the incidence decreased by 11.37-17.39%.Conclusions: Our results based on a real-world setting reaffirmed that a prenatal nutritional intervention could improve the birth outcomes in cases of FGR and further suggested a better effectiveness on late-onset FGR.

Normal human and sheep fetal vessel oxygen saturations by T2 magnetic resonance imaging

KEY POINTS

Human fetal Doppler ultrasound and invasive blood gas measurements obtained by cordocentesis or at the time of delivery reveal similarities with sheep (an extensively used model for human fetal cardiovascular physiology). Oxygen saturation (SO₂ ) measurements in human fetuses have been limited to the umbilical and scalp vessels, providing little information about normal regional SO₂ differences in the fetus. Blood T2 MRI relaxometry presents a non-invasive measure of SO₂ in the major fetal vessels. This study presents the first in vivo validation of fetal vessel T2 oximetry against the in vitro T2-SO₂ relationship using catheterized sheep fetuses and compares the normal SO₂ in the major vessels between the human and sheep fetal circulations. Human fetal vessel SO₂ by T2 MRI confirms many similarities with the sheep fetal circulation and is able to demonstrate regional differences in SO₂ ; in particular the significantly higher SO₂ in the left versus right heart.

ABSTRACT

Blood T2 magnetic resonance imaging (MRI) relaxometry non-invasively measures oxygen saturation (SO₂ ) in major vessels but has not been validated in fetuses in vivo. We compared the blood T2-SO₂ relationship in vitro (tubes) and in vivo (vessels) in sheep, and measured SO₂ across the normal human and sheep fetal circulations by T2. Singleton pregnant ewes underwent surgery to implant vascular catheters. In vitro and in vivo sheep blood T2 measurements were related to corresponding SO₂ measured using a blood gas analyser, as well as relating T2 and SO₂ of human fetal blood in vitro. MRI oximetry was performed in the major vessels of 30 human fetuses at 36 weeks (term, 40 weeks) and 10 fetal sheep (125 days; term, 150 days). The fidelity of in vivo fetal T2 oximetry was confirmed through comparison of in vitro and in vivo sheep blood T2-SO₂ relationships (P = 0.1). SO₂ was similar between human and sheep fetuses, as was the fetal oxygen extraction fraction (human, 33 ± 11%; sheep, 34 ± 7%; P = 0.798). The presence of streaming in the human fetal circulation was demonstrated by the SO₂ gradient between the ascending aorta (68 ± 10%) and the main pulmonary artery (49 ± 9%; P < 0.001). Human and sheep fetal vessel MRI oximetry based on T2 is a validated approach that confirms the presence of streaming of umbilical venous blood towards the heart and brain. Streaming is important in ensuring oxygen delivery to these organs and its disruption may have important implications for organ development, especially in conditions such as congenital heart disease and fetal growth restriction.

Maternal erythrocyte ENT1-mediated AMPK activation counteracts placental hypoxia and supports fetal growth

Insufficient O2 supply is frequently associated with fetal growth restriction (FGR), a leading cause of perinatal mortality and morbidity. Although the erythrocyte is the most abundant and only cell type to deliver O2 in our body, its function and regulatory mechanism in FGR remain unknown. Here, we report that genetic ablation of mouse erythrocyte equilibrative nucleoside transporter 1 (eENT1) in dams, but not placentas or fetuses, results in FGR. Unbiased high-throughput metabolic profiling coupled with in vitro and in vivo flux analyses with isotopically labeled tracers led us to discover that maternal eENT1-dependent adenosine uptake is critical in activating AMPK by controlling the AMP/ATP ratio and its downstream target, bisphosphoglycerate mutase (BPGM); in turn, BPGM mediates 2,3-BPG production, which enhances O2 delivery to maintain placental oxygenation. Mechanistically and functionally, we revealed that genetic ablation of maternal eENT1 increases placental HIF-1α; preferentially reduces placental large neutral aa transporter 1 (LAT1) expression, activity, and aa supply; and induces FGR. Translationally, we revealed that elevated HIF-1α directly reduces LAT1 gene expression in cultured human trophoblasts. We demonstrate the importance and molecular insight of maternal eENT1 in fetal growth and open up potentially new diagnostic and therapeutic possibilities for FGR.

Comparison of placental elasticity in normal and intrauterine growth retardation pregnancies by ex vivo strain elastography

OBJECTIVE

To compare the placental elasticity in fetuses with or without intrauterine growth restriction (IUGR).

MATERIALS AND METHODS

One hundred pregnant women (50 IUGR and 50 healthy) with anteriorly located placenta were evaluated during the third trimester of pregnancy. Measurements were carried out by a machine that has a real-time elastographic ultrasonography feature. After obtaining the optimum image, three areas (subcutaneous tissue, center, and the edge of the placenta) were provided to identify the placental strain values. Then, the placental strain ratio (PSR) value was calculated automatically. Two groups compared in terms of their PSR values.

RESULTS

There was a significant difference in placental elasticity between the groups (P < 0.001). PSR value was 2.8 ± 1.2 in the IUGR group and 1.3 ± 0.6 in the control group. A PSR value of 1.78 had an 86% sensitivity (OR 4.3) and 80% specificity (OR 0.17) in IUGR cases. The positive predictive value was 81.1% and the negative predictive value was 85.1% for this cut-off value.

CONCLUSIONS

We have shown that placental strain ratio is increased during the third trimester of pregnancy in fetuses with IUGR. Increased stiffness and elasticity may be responsible for the onset of IUGR in some cases.

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.

Cardiorespiratory consequences of intrauterine growth restriction: Influence of timing, severity and duration of hypoxaemia

At birth, weight of the neonate is used as a marker of the 9-month journey as a fetus. Those neonates born less than the 10th centile for their gestational age are at risk of being intrauterine growth restricted. However, this depends on their genetic potential for growth and the intrauterine environment in which they grew. Alterations in the supply of oxygen and nutrients to the fetus will decrease fetal growth, but these alterations occur due to a range of causes that are maternal, placental or fetal in nature. Consequently, IUGR neonates are a heterogeneous population. For this reason, it is likely that these neonates will respond differently to interventions compared not only to normally grown fetuses, but also to other neonates that are IUGR but have travelled a different path to get there. Thus, a range of models of IUGR should be studied to determine the effects of IUGR on the development and function of the heart and lung and subsequently the impact of interventions to improve development of these organs. Here we focus on a range of models of IUGR caused by manipulation of the maternal, placental or fetal environment on cardiorespiratory outcomes.

The Neurovascular Unit: Effects of Brain Insults During the Perinatal Period

The neurovascular unit (NVU) is a relatively recent concept in neuroscience that broadly describes the relationship between brain cells and their blood vessels. The NVU incorporates cellular and extracellular components involved in regulating cerebral blood flow and blood-brain barrier function. The NVU within the adult brain has attracted strong research interest and its structure and function is well described, however, the NVU in the developing brain over the fetal and neonatal period remains much less well known. One area of particular interest in perinatal brain development is the impact of known neuropathological insults on the NVU. The aim of this review is to synthesize existing literature to describe structure and function of the NVU in the developing brain, with a particular emphasis on exploring the effects of perinatal insults. Accordingly, a brief overview of NVU components and function is provided, before discussion of NVU development and how this may be affected by perinatal pathologies. We have focused this discussion around three common perinatal insults: prematurity, acute hypoxia, and chronic hypoxia. A greater understanding of processes affecting the NVU in the perinatal period may enable application of targeted therapies, as well as providing a useful basis for research as it expands further into this area.

DNA methylation of the Rtl1 promoter in the placentas with fetal growth restriction

BACKGROUND

Small for gestational age (SGA) babies experience fetal growth restriction because of placental insufficiency, and aberrant fetal growth has been linked to DNA methylation in the placenta. An imprinted gene encoding retrotransposon-like protein 1 (RTL1) is regulated by DNA methylation in the promoter region and plays a key role in placental development. We therefore investigated the DNA methylation status of RTL1 in the placenta of infants with severe SGA.

METHODS

We extracted DNA from the placenta of appropriate for gestational age (AGA; gestational age 35 ± 6 weeks, birthweight 2292 ± 1006 g; n = 12), SGA (birthweight z-score ≤-2 SD, 33 ± 5 weeks, 1373 ± 580 g; n = 11), and severe SGA (birthweight z-score ≤-3 SD, 33 ± 4 weeks, 1145 g ± 423 g; n = 7) infants, and we determined the methylation rates of five CpG sites in the CG4 (82,275,427-82,275,737 in NT_026437 sequence, NCBI database) region of the RTL1 promoter by pyrosequencing. We defined hypermethylation (>75.5%) and hypomethylation (<45.6%) based on the average methylation rate exceeding ± two standard deviations (SD) in the AGA group, respectively, and compared these among groups.

RESULTS

There was no significant difference in the average methylation of CpG1-5 (control 59%, SGA 60%, severe SGA 63%), but abnormal methylation (hyper-/hypo-methylation) in CpG1 differed significantly among the groups (control 0%, SGA 36%, severe SGA 71%).

CONCLUSION

Infants with severe SGA have abnormal placental DNA methylation of CpG1 in the CG4 region of RTL1, suggesting the existence of disturbed epigenetic control in utero.

Premature placental aging in term small-for-gestational-age and growth-restricted fetuses

OBJECTIVE

To perform a comprehensive assessment of the placental aging process in small term fetuses classified as being small-for-gestational age (SGA) or having fetal growth restriction (FGR) through analysis of senescence and apoptosis markers.

METHODS

This was a prospective nested case-control study of singleton pregnancies delivered at term, including 21 control pregnancies with normally grown fetuses and 36 with a small fetus classified as SGA (birth weight between the 3^rd and 9^th percentiles and normal fetoplacental Doppler; n = 18) or FGR (birth weight < 3^rd percentile and/or abnormal cerebroplacental ratio and/or uterine artery Doppler; n = 18). Telomerase activity, telomere length (quantified by comparing the amount of amplification product for the telomere sequence (T) to that of a single copy of the gene 36B4 (S)) and RNA expression of senescence (Sirtuins 1, 3 and 6) and apoptosis (p53, p21, BAX and Caspases 3 and 9) markers (analyzed using the 2^-ΔΔCt method) were determined in placental samples collected at birth and compared between the three groups.

RESULTS

Compared to pregnancies with a normally grown fetus, both SGA and FGR pregnancies presented signs of accelerated placental aging, including lower telomerase activity (mean ± SD, 12.8 ± 6.6% in controls vs 7.98 ± 4.2% in SGA vs 7.79 ± 4.6% in FGR; P = 0.008), shorter telomeres (mean ± SD T/S ratio, 1.20 ± 0.6 in controls vs 1.08 ± 0.9 in SGA vs 0.66 ± 0.5 in FGR; P = 0.047) and reduced Sirtuin-1 RNA expression (mean ± SD 2^-ΔΔCt , 1.55 ± 0.8 in controls vs 0.91 ± 0.8 in SGA vs 0.63 ± 0.5 in FGR; P = 0.001) together with increased p53 RNA expression (median (interquartile range) 2^-ΔΔCt , 1.07 (0.3-3.3) in controls vs 5.39 (0.6-15) in SGA vs 3.75 (0.9-7.8) in FGR; P = 0.040). FGR cases presented signs of apoptosis, with increased Caspase-3 RNA levels (median (interquartile range) 2^-ΔΔCt , 0.94 (0.7-1.7) in controls vs 3.98 (0.9-31) in FGR; P = 0.031) and Caspase-9 RNA levels (median (interquartile range) 2^-ΔΔCt , 1.21 (0.6-4.0) in controls vs 3.87 (1.5-9.0) in FGR; P = 0.037) compared with controls. In addition, Sirtuin-1 RNA expression, telomerase activity, telomere length and Caspase-3 activity showed significant linear trends across groups as severity of the condition increased.

CONCLUSIONS

Accelerated placental aging was observed in both clinical forms of late-onset fetal smallness (SGA and FGR), supporting a common pathophysiology and challenging the concept of SGA fetuses being constitutionally small. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Diagnostic performance of third-trimester ultrasound for the prediction of late-onset fetal growth restriction: a systematic review and meta-analysis

OBJECTIVE

The objective of the study was to establish the diagnostic performance of ultrasound screening for predicting late smallness for gestational age and/or fetal growth restriction.

DATA SOURCES

A systematic search was performed to identify relevant studies published since 2007 in English, Spanish, French, Italian, or German, using the databases PubMed, ISI Web of Science, and SCOPUS.

STUDY ELIGIBILITY CRITERIA

We used rrospective and retrospective cohort studies in low-risk or nonselected singleton pregnancies with screening ultrasound performed at ≥32 weeks of gestation.

STUDY APPRAISAL AND SYNTHESIS METHODS

The estimated fetal weight and fetal abdominal circumference were assessed as index tests for the prediction of birthweight <10th (i.e. smallness for gestational age), less than the fifth, and less than the third centile and fetal growth restriction (estimated fetal weight less than the third or estimated fetal weight <10th plus Doppler signs). Quality of the included studies was independently assessed by 2 reviewers, using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. For the meta-analysis, hierarchical summary receiver-operating characteristic curves were constructed, and quantitative data synthesis was performed using random-effects models. The sensitivity of the abdominal circumference <10th centile and estimated fetal weight <10th centile for a fixed 10% false-positive rate was derived from the corresponding hierarchical summary receiver-operating characteristic curves. Heterogeneity between studies was visually assessed using Galbraith plots, and publication bias was assessed by funnel plots and quantified by Deeks' method.

RESULTS

A total of 21 studies were included. Observed pooled sensitivities of abdominal circumference and estimated fetal weight <10th centile for birthweight <10th centile were 35% (95% confidence interval, 20-52%) and 38% (95% confidence interval, 31-46%), respectively. Observed pooled specificities were 97% (95% confidence interval, 95-98%) and 95% (95% confidence interval, 93-97%), respectively. Modeled sensitivities of abdominal circumference and estimated fetal weight <10th centile for 10% false-positive rate were 78% (95% confidence interval, 61-95%) and 54% (95% confidence interval, 46-52%), respectively. The sensitivity of estimated fetal weight <10th centile was better when aimed to fetal growth restriction than to smallness for gestational age. Meta-regression analysis showed a significant increase in sensitivity when ultrasound evaluation was performed later in pregnancy (P = .001).

CONCLUSION

Third-trimester abdominal circumference and estimated fetal weight perform similar in predicting smallness for gestational age. However, for a fixed 10% false-positive rate extrapolated sensitivity is higher for abdominal circumference. There is evidence of better performance when the scan is performed near term and when fetal growth restriction is the targeted condition.

Metabolic profiling and targeted lipidomics reveals a disturbed lipid profile in mothers and fetuses with intrauterine growth restriction

Fetal growth may be impaired by poor placental function or maternal conditions, each of which can influence the transfer of nutrients and oxygen from the mother to the developing fetus. Large-scale studies of metabolites (metabolomics) are key to understand cellular metabolism and pathophysiology of human conditions. Herein, maternal and cord blood plasma samples were used for NMR-based metabolic fingerprinting and profiling, including analysis of the enrichment of circulating lipid classes and subclasses, as well as the number of sub-fraction particles and their size. Changes in phosphatidylcholines and glycoproteins were prominent in growth-restricted fetuses indicating significant alterations in their abundance and biophysical properties. Lipoprotein profiles showed significantly lower plasma concentrations of cholesterol-intermediate density lipoprotein (IDL), triglycerides-IDL and high-density lipoprotein (HDL) in mothers of growth-restricted fetuses compared to controls (p < 0.05). In contrast, growth-restricted fetuses had significantly higher plasma concentrations of cholesterol and triglycerides transporting lipoproteins [LDL, IDL, and VLDL, (p < 0.005; all)], as well as increased VLDL particle types (large, medium and small). Significant changes in plasma concentrations of formate, histidine, isoleucine and citrate in growth-restricted fetuses were also observed. Comprehensive metabolic profiling reveals that both, mother and fetuses of pregnancies complicated with fetal growth restriction have a substantial disruption in lipid metabolism.

Nitrite mediated vasorelaxation in human chorionic plate vessels is enhanced by hypoxia and dependent on the NO-sGC-cGMP pathway

Adequate perfusion of the placental vasculature is essential to meet the metabolic demands of fetal growth and development. Lacking neural control, local tissue metabolites, circulating and physical factors contribute significantly to blood flow regulation. Nitric oxide (NO) is a key regulator of fetoplacental vascular tone. Nitrite, previously considered an inert end-product of NO oxidation, has been shown to provide an important source of NO. Reduction of nitrite to NO may be particularly relevant in tissue when the oxygen-dependent NO synthase (NOS) activity is compromised, e.g. in hypoxia. The contribution of this pathway in the placenta is currently unknown. We hypothesised that nitrite vasodilates human placental blood vessels, with enhanced efficacy under hypoxia. Placentas were collected from uncomplicated pregnancies and the vasorelaxant effect of nitrite (10^-6-5x10^-3 M) was assessed using wire myography on isolated pre-constricted chorionic plate arteries (CPAs) and veins (CPVs) under normoxic (pO₂ ∼5%) and hypoxic (pO₂ ∼1%) conditions. The dependency on the NO-sGC-cGMP pathway and known nitrite reductase (NiR) activities was also investigated. Nitrite caused concentration-dependent vasorelaxation in both arteries and veins, and this effect was enhanced by hypoxia, significantly in CPVs (P < 0.01) and with a trend in CPAs (P = 0.054). Pre-incubation with NO scavengers (cPTIO and oxyhemoglobin) attenuated (P < 0.01 and P < 0.0001, respectively), and the sGC inhibitor ODQ completely abolished nitrite-mediated vasorelaxation, confirming the involvement of NO and sGC. Inhibition of potential NiR enzymes xanthine oxidoreductase, mitochondrial aldehyde dehydrogenase and mitochondrial bc₁ complex did not attenuate vasorelaxation. This data suggests that nitrite may provide an important reservoir of NO bioactivity within the placenta to enhance blood flow when fetoplacental oxygenation is impaired, as occurring in pregnancy diseases such as pre-eclampsia and fetal growth restriction.

Longitudinal growth assessment for prediction of adverse perinatal outcome in fetuses suspected to be small-for-gestational age

OBJECTIVE

Fetal growth restriction (FGR) is associated with an increased risk of adverse perinatal outcome. However, distinguishing this condition from small-for-gestational age (SGA) remains elusive. A set of criteria has been proposed recently for such a purpose, including the degree of smallness, Doppler parameters and growth velocity. The aim of this study was to establish whether the use of growth velocity adds value to Doppler assessment in predicting adverse perinatal outcome among SGA-suspected fetuses.

METHODS

This was a prospective cohort study of consecutive singleton pregnancies with late (diagnosis ≥ 32.0 weeks) SGA (estimated fetal weight (EFW) < 10^th centile). Longitudinal growth assessment was performed by calculation of EFW z-velocity between diagnosis and last scan before delivery. Improvement in the association with and predictive performance of EFW z-velocity for adverse perinatal outcome was compared against standard criteria of FGR evaluated before delivery (EFW < 3^rd centile, abnormal uterine Doppler or abnormal cerebroplacental ratio).

RESULT

A total of 472 patients were evaluated prospectively for suspected SGA. Of these, 231 (48.9%) qualified as late FGR. Univariate analysis showed a significant trend towards higher frequency (14.5% vs 8.2%; P = 0.041) of EFW z-velocity in the lowest decile in pregnancies with adverse perinatal outcome. Nonetheless, the addition of EFW z-velocity improved neither the association with nor the predictive performance of standard criteria of FGR for adverse perinatal outcome.

CONCLUSIONS

Longitudinal assessment of fetal growth by means of EFW z-velocity did not have any independent predictive value for adverse perinatal outcome when used in combination with Doppler in SGA-suspected fetuses. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Evaluation of Umbilical Artery Doppler Indices in Pregnant Women With Sickle Cell Anemia Disease at a Nigerian Tertiary Hospital

Pregnant patients with sickle cell anemia (HbSS) are at risk of adverse outcomes to the mother and the fetus due to unique pathophysiologic changes. The purpose of this study was to determine the umbilical artery (UA) Doppler indices at 26 weeks gestational age (GA) in HbSS women with uncomplicated pregnancies and compare with the obstetric outcome. In this cohort study, 60 HbSS and 60 normal hemoglobin (HbAA) women with uncomplicated pregnancies were recruited from the antenatal clinic and prospectively followed to delivery. UA velocimetry, fetal biometry, maternal hematocrit, and parity were assessed at 26 weeks. Fetomaternal outcomes were also documented. UA Doppler indices and estimated fetal weights were comparable to those of HbAA control subjects at 26 weeks GA. There was a statistically significant increase in adverse obstetric outcomes in HbSS patients. There was no correlation between maternal hematocrit and artery indices. Further research is required to determine cutoff values and optimal timing for sonography in HbSS patients.

Analytical model of the feto-placental vascular system: consideration of placental oxygen transport

The placenta is a transient vascular organ that enables nutrients and blood gases to be exchanged between fetal and maternal circulations. Herein, the structure and oxygen diffusion across the trophoblast membrane between the fetal and maternal red blood cells in the feto-placental vasculature system in both human and mouse placentas are presented together as a functional unit. Previous models have claimed that the most efficient fetal blood flow relies upon structures containing a number of 'conductive' symmetrical branches, offering a path of minimal resistance that maximizes blood flow to the terminal villi, where oxygen diffusion occurs. However, most of these models have disregarded the actual descriptions of the exchange at the level of the intermediate and terminal villi. We are proposing a 'mixed model' whereby both 'conductive' and 'terminal' villi are presumed to be present at the end of single (in human) or multiple (in mouse) pregnancies. We predict an optimal number of 18 and 22 bifurcation levels in the human and the mouse placentas, respectively. Wherever possible, we have compared our model's predictions with experimental results reported in the literature and found close agreement between them.

Diagnosis and surveillance of late-onset fetal growth restriction

By consensus, late fetal growth restriction is that diagnosed >32 weeks. This condition is mildly associated with a higher risk of perinatal hypoxic events and suboptimal neurodevelopment. Histologically, it is characterized by the presence of uteroplacental vascular lesions (especially infarcts), although the incidence of such lesions is lower than in preterm fetal growth restriction. Screening procedures for fetal growth restriction need to identify small babies and then differentiate between those who are healthy and those who are pathologically small. First- or second-trimester screening strategies provide detection rates for late smallness for gestational age <50% for 10% of false positives. Compared to clinically indicated ultrasonography in the third trimester, universal screening triples the detection rate of late smallness for gestational age. As opposed to early third-trimester ultrasound, scanning late in pregnancy (around 37 weeks) increases the detection rate for birthweight <3rd centile. Contrary to early fetal growth restriction, umbilical artery Doppler velocimetry alone does not provide good differentiation between late smallness for gestational age and fetal growth restriction. A combination of biometric parameters (with severe smallness usually defined as estimated fetal weight or abdominal circumference <3rd centile) with Doppler criteria of placental insufficiency (either in the maternal [uterine Doppler] or fetal [cerebroplacental ratio] compartments) offers a classification tool that correlates with the risk for adverse perinatal outcome. There is no evidence that induction of late fetal growth restriction at term improves perinatal outcomes nor is it a cost-effective strategy, and it may increase neonatal admission when performed <38 weeks.

Maternal body mass index impacts fetal-placental size at birth and umbilical cord oxygen values with implications for regulatory mechanisms

BACKGROUND

Maternal under- and over-nutrition are known to effect fetal growth with altered placental development and nutrient transport, but whether fetal oxygenation is also altered remains unknown.

AIMS

To examine linkages between maternal BMI and birth weights, placental weights, and umbilical vein and artery PO_2, with implications for signaling mechanisms.

STUDY DESIGN

Population-based cohort study.

SUBJECTS

Analysis of hospital database information on all patients with pre-pregnant BMI values delivering viable, singleton infants between Jan 1, 1999 and Dec 31, 2010 (N=29,212). BMI was categorized into underweight, normal weight, overweight, and obese, with birth weights categorized into small (SGA), appropriate (AGA), and large for gestational age (LGA).

OUTCOME MEASURES

Maternal BMI, birth and placental weights, umbilical vein and artery PO₂.

RESULTS

Underweight mothers with smaller infants and overweight/obese mothers with larger infants had disproportionately large placentas, suggesting compensatory and/or enhanced placental growth in these pregnancies. All SGA infants had lower umbilical vein and artery PO₂, consistent with aberrant placental development leading to diffusional impairment of oxygen. Both maternal overweight/obese BMI and LGA resulted in lower artery PO₂, likely due to increased growth rates with the larger size in these infants.

CONCLUSIONS

These findings support fetal hypoxemia as a common determinant of growth restriction, whether in underweight mothers and due to under-nutrition or in overweight/obese mothers and due to placental insufficiency. However, oxygen is unlikely to be the primary promotor for fetal growth in overweight/obese mothers and LGA infants, with other substrates of more importance as nutritional cues in these pregnancies.

Mechanisms of fetal epigenetics that determine telomere dynamics and health span in adulthood

Advances in epigenetics now enable us to better understand environmental influences on the genetic background of human diseases. This refers especially to fetal development where an adverse intrauterine environment impacts oxygen and nutrient supply to the fetus. Recently, differences in telomere length and telomere loss dynamics among individuals born with intrauterine growth restriction compared to normal controls have been described. In this paper we propose possible molecular mechanisms that (pre)program telomere epigenetics during pregnancy. This programming sets differences in telomere lengths and dynamics of telomere shortening in adulthood and therefore dictates the dynamics of aging and morbidity in later life.

Modulatory Mechanism of Polyphenols and Nrf2 Signaling Pathway in LPS Challenged Pregnancy Disorders

Early embryonic loss and adverse birth outcomes are the major reproductive disorders that affect both human and animals. The LPS induces inflammation by interacting with robust cellular mechanism which was considered as a plethora of numerous reproductive disorders such as fetal resorption, preterm birth, teratogenicity, intrauterine growth restriction, abortion, neural tube defects, fetal demise, and skeletal development retardation. LPS-triggered overproduction of free radicals leads to oxidative stress which mediates inflammation via stimulation of NF-κB and PPARγ transcription factors. Flavonoids, which exist in copious amounts in nature, possess a wide array of functions; their supplementation during pregnancy activates Nrf2 signaling pathway which encounters pregnancy disorders. It was further presumed that the development of strong antioxidant uterine environment during gestation can alleviate diseases which appear at adult stages. The purpose of this review is to focus on modulatory properties of flavonoids on oxidative stress-mediated pregnancy insult and abnormal outcomes and role of Nrf2 activation in pregnancy disorders. These findings would be helpful for providing new insights in ameliorating oxidative stress-induced pregnancy disorders.

Maternal nutrient restriction in guinea pigs leads to fetal growth restriction with evidence for chronic hypoxia

BackgroundWe determined whether maternal nutrient restriction (MNR) in guinea pigs leading to fetal growth restriction (FGR) impacts markers for tissue hypoxia, implicating a mechanistic role for chronic hypoxia.MethodsGuinea pigs were fed ad libitum (Control) or 70% of the control diet before pregnancy, switching to 90% at mid-pregnancy (MNR). Near term, hypoxyprobe-1 (HP-1), a marker of tissue hypoxia, was injected into pregnant sows. Fetuses were then necropsied and liver, kidney, and placental tissues were processed for erythropoietin (EPO), EPO-receptor (EPOR), and vascular endothelial growth factor (VEGF) protein levels, and for HP-1 immunoreactivity (IR).ResultsFGR-MNR fetuses were 36% smaller with asymmetrical growth restriction compared to controls. EPO and VEGF protein levels were increased in the female FGR-MNR fetuses, providing support for hypoxic stimulus and linkage to increased erythropoiesis, but not in the male FGR-MNR fetuses, possibly reflecting a weaker link between oxygenation and erythropoiesis. HP-1 IR was increased in the liver and kidneys of both male and female FGR-MNR fetuses as an index of local tissue hypoxia, but with no changes in the placenta.ConclusionChronic hypoxia is likely to be an important signaling mechanism for the decreased fetal growth seen with maternal undernutrition and appears to be post-placental in nature.

Revealed versus concealed criteria for placental insufficiency in an unselected obstetric population in late pregnancy (RATIO37): randomised controlled trial study protocol

INTRODUCTION

Fetal growth restriction (FGR) affects 5%-10% of all pregnancies, contributing to 30%-50% of stillbirths. Unfortunately, growth restriction often is not detected antenatally. The last weeks of pregnancy are critical for preventing stillbirth among babies with FGR because there is a pronounced increase in stillbirths among growth-restricted fetuses after 37 weeks of pregnancy. Here we present a protocol (V.1, 23 May 2016) for the RATIO37 trial, which evaluates an integrated strategy for accurately selecting at-risk fetuses for delivery at term. The protocol is based on the combination of fetal biometry and cerebroplacental ratio (CPR). The primary objective is to reduce stillbirth rates. The secondary aims are to detect low birth weights and adverse perinatal outcomes.

METHODS AND ANALYSIS

The study is designed as multicentre (Spain, Chile, Mexico,Czech Republic and Israel), open-label, randomised trial with parallel groups. Singleton pregnancies will be invited to participate after routine second-trimester ultrasound scan (19+0-22+6 weeks of gestation), and participants will be randomly allocated to receive revealed or concealed CPR evaluation. Then, a routine ultrasound and Doppler scan will be performed at 36+0-37+6 weeks. Sociodemographic and clinical data will be collected at enrolment. Ultrasound and Doppler variables will be recorded at 36+0-37+6 weeks of pregnancy. Perinatal outcomes will be recorded after delivery. Univariate (with estimated effect size and its 95% CI) and multivariate (mixed-effects logistic regression) comparisons between groups will be performed.

ETHICS AND DISSEMINATION

The study will be conducted in accordance with the principles of Good Clinical Practice. This study was accepted by the Clinical Research Ethics Committee of Hospital Clinic Barcelona on 23May 2016. Subsequent approval by individual ethical committees and competent authorities was granted. The study results will be published in peer-reviewed journals and disseminated at international conferences.

TRIAL REGISTRATION NUMBER

NCT02907242; pre-results.

Sex differences in the effects of prenatal lead exposure on birth outcomes

Studies on the associations between prenatal lead exposure and birth outcomes have been inconsistent, and few data are available on the sex differences in these associations. We measured the cord blood lead levels of newborns in Shanghai and determined their associations with birth outcomes, which included birth weight, birth length, head circumference, and the ponderal index, in the total sample and within sex subgroups. A total of 1009 mother-infant pairs were enrolled from 10 hospitals in Shanghai between September 2008 and October 2009. The geometric mean of the cord blood lead concentrations was 4.07 μg/dl (95% CI: 3.98-4.17 μg/dl). A significant inverse association was found between cord blood lead levels and head circumference only in the male subgroup, and increasing cord blood lead levels were related to significant decreases in the ponderal index only in females. The birth weights of the male infants were positively associated with cord blood lead levels; after adjusting for the maternal intake frequency of preserved eggs, the estimated mean differences in birth weights decreased by 11.7% for each 1-unit increase in the log10-transformed cord blood lead concentration. Our findings suggest that prenatal lead exposure may have sex-specific effects on birth outcomes and that maternal dietary intake may be a potential confounder in these relationships. Further studies on this topic are highly warranted.

Placental NFE2L2 is discordantly activated in monochorionic twins with selective intrauterine growth restriction and possibly regulated by hypoxia

INTRODUCTION

Nuclear factor, erythroid 2 like 2 (NFE2L2) is an important transcription factor that protects cells from oxidative stress (OS). NFE2L2 deficiency in placentas is associated with pregnancy complications. We have demonstrated that elevated OS existed in placental shares of the smaller fetus in selective intrauterine growth restriction (sIUGR); however, the role of NFE2L2 in the development of sIUGR remains unknown. In this study, we examined the levels of NFE2L2 and heme oxygenase 1 (HMOX1), a major antioxidant regulated by NFE2L2, in sIUGR placentas. We also investigated the relationship between hypoxia and NFE2L2 activation, which may be involved in the pathogenesis of sIUGR.

METHODS

Real-time PCR, Western blot, and immunohistochemistry were used to detect the levels of NFE2L2 and HMOX1 in placentas from 30 monochorionic diamniotic (MCDA) twin pregnancies. The trophoblast cell line HTR-8/SVneo was cultured under severe (3%) or mild (10%) hypoxia.

RESULTS

NFE2L2 and HMOX1 were both up-regulated in placental shares of the smaller fetus in the sIUGR group. No significant inter-twin differences in NFE2L2 and HMOX1 were detected in the normal group. In vitro, NFE2L2 was suppressed under severe hypoxia (3% O₂) but was clearly up-regulated under mild hypoxia (10% O₂).

DISCUSSION

Compared with the suppression of NFE2L2 in placentas of fetal growth restriction (FGR) in singleton pregnancies, NFE2L2 was up-regulated in placental shares of the smaller fetus in sIUGR pregnancies. The asymmetrical activation of NFE2L2 in placental shares of sIUGR twins may be a compensation for hypoxia that protects the smaller fetus from OS damage.

Differential performance of first-trimester screening in predicting small-for-gestational-age neonate or fetal growth restriction

OBJECTIVE

To assess the ability of integrated first-trimester screening, combining maternal characteristics and biophysical and biochemical markers, to predict delivery of a small-for-gestational-age (SGA) neonate, and compare this with its ability to predict fetal growth restriction (FGR).

METHODS

This was a prospective cohort study of singleton pregnancies undergoing routine first-trimester screening. SGA was defined as birth weight (BW) < 10^th percentile and FGR was defined as an ultrasound estimated fetal weight < 10^th percentile plus Doppler abnormalities, or BW < 3^rd percentile. Logistic regression-based predictive models were developed for predicting SGA and FGR. Models incorporated the a-priori risk from maternal characteristics, and mean arterial pressure, uterine artery Doppler, placental growth factor and soluble fms-like tyrosine kinase-1.

RESULTS

In total, 9150 births were included. Of these, 979 (10.7%) qualified for a postnatal diagnosis of SGA and 462 (5.0%) for a prenatal diagnosis of FGR. For predicting SGA, the model achieved a detection rate of 35% for a false-positive rate (FPR) of 5% and 42% for a 10% FPR. The model's performance was significantly higher for predicting FGR (P < 0.001), with detection rates of 59% and 67%, for a FPR of 5% and 10%, respectively.

CONCLUSION

The predictive performance of first-trimester screening for cases with growth impairment by a combination of maternal characteristics and biophysical and biochemical markers is improved significantly when a prenatal and strict definition of FGR is used rather than a postnatal definition based on BW. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Brain metabolite alterations in infants born preterm with intrauterine growth restriction: association with structural changes and neurodevelopmental outcome

BACKGROUND

Intrauterine growth restriction and premature birth represent 2 independent problems that may occur simultaneously and contribute to impaired neurodevelopment.

OBJECTIVE

The objective of the study was to assess changes in the frontal lobe metabolic profiles of 1 year old intrauterine growth restriction infants born prematurely and adequate-for-gestational-age controls, both premature and term adequate for gestational age and their association with brain structural and biophysical parameters and neurodevelopmental outcome at 2 years.

STUDY DESIGN

A total of 26 prematurely born intrauterine growth restriction infants (birthweight <10th centile for gestational age), 22 prematurely born but adequate for gestational age controls, and 26 term adequate-for-gestational-age infants underwent brain magnetic resonance imaging and magnetic resonance spectroscopy at 1 year of age during natural sleep, on a 3 Tesla scanner. All brain T1-weighted and diffusion-weighted images were acquired along with short echo time single-voxel proton spectra from the frontal lobe. Magnetic resonance imaging/magnetic resonance spectroscopy data were processed to derive structural, biophysical, and metabolic information, respectively. Neurodevelopment was evaluated at 2 years of age using the Bayley Scales 3rd edition, assessing cognitive, language, motor, socioemotional, and adaptive behavior.

RESULTS

Prematurely born intrauterine growth restriction infants had slightly smaller brain volumes and increased frontal lobe white matter mean diffusivity compared with both prematurely born but adequate for gestational age and term adequate for gestational age controls. Frontal lobe N-acetylaspartate levels were significantly lower in prematurely born intrauterine growth restriction than in prematurely born but adequate for gestational age infants but increased in prematurely born but adequate for gestational age compared with term adequate-for-gestational-age infants. The prematurely born intrauterine growth restriction group also showed slightly lower choline compounds, borderline decrements of estimated glutathione levels, and increased myoinositol to choline ratios, compared with prematurely born but adequate for gestational age controls. These specific metabolite changes were locally correlated to lower gray matter content and increased mean diffusivity and reduced white matter fraction and fractional anisotropy. Prematurely born intrauterine growth restriction infants also showed a tendency for poorer neurodevelopmental outcome at 2 years, associated with lower levels of frontal lobe N-acetylaspartate at 1 year within the preterm subset.

CONCLUSIONS

Preterm intrauterine growth restriction infants showed altered brain metabolite profiles during a critical stage of brain maturation, which correlate with brain structural and biophysical parameters and neurodevelopmental outcome. Our results suggest altered neurodevelopmental trajectories in preterm intrauterine growth restriction and adequate-for-gestational-age infants, compared with term adequate-for-gestational-age infants, which require further characterization.

Villus packing density and lacunarity: Markers of placental efficiency?

We evaluate, in routine H&E histology slides, villus quantity in a given area (villous packing density, VPD) and the pattern or "gappiness" of villous distribution (lacunarity), and test for correlations with a proxy for fetoplacental metabolic rate, β calculated as (ln (placental weight)/ln (birthweight)) from Kleiber's law [1]. Three ∼4.3 mm² images each were obtained from 88 term placentas. Ranges of VPD and lacunarity were each correlated with β (r = 0.31, p = 0.003, r = 0.23, p = 0.03 and respectively). The relationship between β and within-placenta variation in VPD and lacunarity highlights the need to study not merely the mean but the variance of villous geometries and spatial distributions.