Predictive value of sFlt-1, PlGF, sFlt-1/PlGF ratio and PAPP-A for late-onset preeclampsia and IUGR between 32 and 37 weeks of pregnancy

Prognostic value of angiogenic markers in pregnancy with fetal growth restriction

OBJECTIVE

Pregnancies with fetal growth restriction (FGR) are at increased risk for pre-eclampsia. Angiogenic markers including soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) are altered in pregnancies complicated by FGR, but their utility for predicting pre-eclampsia in growth-restricted pregnancies is uncertain. This study aimed to evaluate the prognostic value of angiogenic markers for predicting the development of pre-eclampsia in pregnancies with FGR and suspected pre-eclampsia.

METHODS

This was a retrospective study of singleton pregnancies with FGR, defined according to Delphi consensus criteria, which underwent sampling of sFlt-1 and PlGF for suspicion of pre-eclampsia at the Medical University of Vienna, Vienna, Austria, between 2013 and 2020. Women with an established diagnosis of pre-eclampsia at sampling were excluded. Cox regression analysis and logistic regression analysis were performed to evaluate the association of angiogenic markers with the development of pre-eclampsia at various timepoints.

RESULTS

In this cohort of 93 women, pre-eclampsia was diagnosed in 14 (15.1%) women within 1 week after sampling, 21 (22.6%) within 2 weeks after sampling and 38 (40.9%) at any time after assessment. The sFlt-1/PlGF ratio consistently showed a stronger association with the development of pre-eclampsia compared to sFlt-1 or PlGF alone (pre-eclampsia within 1 week: area under the receiver-operating-characteristics curve, 0.87 vs 0.82 vs 0.72). Models including the sFlt-1/PlGF ratio were associated more strongly with pre-eclampsia hazard compared to models including sFlt-1 or PlGF alone (concordance index, 0.790 vs 0.759 vs 0.755). The risk classification capability of the sFlt-1/PlGF ratio decreased after the 2-week timepoint. The established cut-off value for the sFlt-1/PlGF ratio of < 38 was effective for ruling out pre-eclampsia within 2 weeks, with a negative predictive value of 0.933 and sensitivity of 0.952.

CONCLUSIONS

Use of the sFlt-1/PlGF ratio is preferrable to the use of PlGF alone for the prediction of pre-eclampsia in pregnancies with FGR. Established cut-offs for ruling out the development of pre-eclampsia in the short term seem to be effective in these patients. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Prediction of Intrauterine Growth Restriction and Preeclampsia Using Machine Learning-Based Algorithms: A Prospective Study

(1) Background: Prenatal care providers face a continuous challenge in screening for intrauterine growth restriction (IUGR) and preeclampsia (PE). In this study, we aimed to assess and compare the predictive accuracy of four machine learning algorithms in predicting the occurrence of PE, IUGR, and their associations in a group of singleton pregnancies; (2) Methods: This observational prospective study included 210 singleton pregnancies that underwent first trimester screenings at our institution. We computed the predictive performance of four machine learning-based methods, namely decision tree (DT), naïve Bayes (NB), support vector machine (SVM), and random forest (RF), by incorporating clinical and paraclinical data; (3) Results: The RF algorithm showed superior performance for the prediction of PE (accuracy: 96.3%), IUGR (accuracy: 95.9%), and its subtypes (early onset IUGR, accuracy: 96.2%, and late-onset IUGR, accuracy: 95.2%), as well as their association (accuracy: 95.1%). Both SVM and NB similarly predicted IUGR (accuracy: 95.3%), while SVM outperformed NB (accuracy: 95.8 vs. 94.7%) in predicting PE; (4) Conclusions: The integration of machine learning-based algorithms in the first-trimester screening of PE and IUGR could improve the overall detection rate of these disorders, but this hypothesis should be confirmed in larger cohorts of pregnant patients from various geographical areas.

Maternal serum soluble fms-like tyrosine kinase-1-to-placental growth factor ratio distinguishes growth-restricted from non-growth-restricted small-for-gestational-age fetuses

BACKGROUND

Fetal growth restriction secondary to chronic placental insufficiency is a major cause of perinatal morbidity and mortality. A significant proportion of fetuses with fetal growth restriction are small for gestational age, defined as a birthweight of ≤10th percentile. However, not all small-for-gestational-age fetuses are growth restricted. Some are constitutionally small and otherwise healthy. It is important to distinguish between small-for-gestational-age fetuses with and without fetal growth restriction to ensure appropriate interventions in small-for-gestational-age fetuses with fetal growth restriction and to minimize unnecessary interventions in healthy small-for-gestational-age fetuses. The maternal serum ratio of soluble fms-like tyrosine kinase-1 and placental growth factor is an indicator of placental insufficiency in the latter half of pregnancy. As such, the soluble fms-like tyrosine kinase-1-to-placental growth factor ratio may be a clinically useful tool to distinguish between small-for-gestational-age fetuses with and without fetal growth restriction.

OBJECTIVE

This study aimed to determine whether the soluble fms-like tyrosine kinase-1-to-placental growth factor ratio can distinguish between small-for-gestational-age fetuses with and without fetal growth restriction with a birthweight of ≤10th percentile.

STUDY DESIGN

A retrospective audit of 233 singleton pregnancies delivering an infant with a birthweight of ≤10th percentile corrected for gestational age with an antenatal maternal serum soluble fms-like tyrosine kinase-1-to-placental growth factor result was performed. Fetal growth restriction was defined as a birthweight of ≤10th percentile with an umbilical artery pulsatility index of >95th percentile, fetal middle cerebral artery pulsatility index of <5th percentile, amniotic fluid index of <6 cm, and/or cerebroplacental ratio of <1st percentile. The soluble fms-like tyrosine kinase-1-to-placental growth factor ratios before delivery between fetuses with and without fetal growth restriction (121 [fetal growth restriction] vs 112 [no fetal growth restriction]) were compared. The Student t test and Fisher exact test were used to compare cases and controls. The Mann-Whitney U test, linear regression analysis, and Spearman correlation coefficient (Rho) were used to examine associations between the soluble fms-like tyrosine kinase-1-to-placental growth factor ratio and fetal outcomes to determine whether the soluble fms-like tyrosine kinase-1-to-placental growth factor ratio served as a prognostic marker of fetal growth restriction severity.

RESULTS

The mean soluble fms-like tyrosine kinase-1-to-placental growth factor ratio was increased in fetal growth restriction cases compared with non-fetal growth restriction controls (234.3±25.0 vs 67.4±7.7, respectively; P<.0001). When controlling for preeclampsia, which is associated with placental insufficiency, fetal growth restriction cases still demonstrated an independent increase in the soluble fms-like tyrosine kinase-1-to-placental growth factor ratio (effect size, 0.865; 95% confidence interval, 0.509-1.220; P<.001). The soluble fms-like tyrosine kinase-1-to-placental growth factor ratio was negatively correlated with birthweight percentiles in pregnancies delivering an infant with a birthweight of ≤10th percentile (r=-0.3565; P<.0001). This association was maintained for fetuses with fetal growth restriction (r=-0.2309; P<.05), whereas fetuses without fetal growth restriction had no significant correlation between the soluble fms-like tyrosine kinase-1-to-placental growth factor ratio and neonatal birthweight percentiles.

CONCLUSION

The soluble fms-like tyrosine kinase-1-to-placental growth factor ratio was significantly higher in small-for-gestational-age fetuses with fetal growth restriction than small-for-gestational-age fetuses without fetal growth restriction, independent of preeclampsia. Furthermore, the soluble fms-like tyrosine kinase-1-to-placental growth factor ratio was negatively correlated with fetal growth restriction birthweight percentiles, suggesting that it may be a clinical measure of fetal growth restriction severity. Therefore, the ratio may usefully delineate fetal growth restriction from constitutionally small but otherwise healthy fetuses antenatally, allowing for timely interventions in small-for-gestational-age cases with fetal growth restriction and unnecessary interventions to be minimized in small-for-gestational-age cases without fetal growth restriction.

Discovery and verification of extracellular microRNA biomarkers for diagnostic and prognostic assessment of preeclampsia at triage

We report on the identification of extracellular miRNA (ex-miRNA) biomarkers for early diagnosis and prognosis of preeclampsia (PE). Small RNA sequencing of maternal serum prospectively collected from participants undergoing evaluation for suspected PE revealed distinct patterns of ex-miRNA expression among different categories of hypertensive disorders in pregnancy. Applying an iterative machine learning method identified three bivariate miRNA biomarkers (miR-522-3p/miR-4732-5p, miR-516a-5p/miR-144-3p, and miR-27b-3p/let-7b-5p) that, when applied serially, distinguished between PE cases of different severity and differentiated cases from controls with a sensitivity of 93%, specificity of 79%, positive predictive value (PPV) of 55%, and negative predictive value (NPV) of 89%. In a small independent validation cohort, these ex-miRNA biomarkers had a sensitivity of 91% and specificity of 57%. Combining these ex-miRNA biomarkers with the established sFlt1:PlGF protein biomarker ratio performed better than either set of biomarkers alone (sensitivity of 89.4%, specificity of 91.3%, PPV of 95.5%, and NPV of 80.8%).

Expression of vascular endothelial growth factor A (VEGFA), placental growth factor (PlGF) and insulin-like growth factor 1 (IGF-1) in serum from women undergoing frozen embryo transfer

VEGFA, PlGF and IGF-1 are three main angiogenic factors which play significant roles in embryo implantation. However, the relationship between serum expressions of VEGFA, PlGF and IGF-1 and pregnancy outcomes has not been fully illustrated. In this study, serum specimens were collected precisely on day 7 after the LH surge in a natural non-conception cycle from 38 infertile patients who underwent frozen embryo transfer (FET) treatment. ELISA was used to determine the concentrations of VEGFA, PlGF and IGF-1. Serum levels of VEGFA, PlGF and IGF-1 were compared between patients who conceived (n=25) and who did not (n=13). Correlation and linear regression analyses were used to investigate the correlations of serum angiogenic factors and β-hCG MoM levels in the pregnant group. The results demonstrated that no significant difference was found in serum VEGFA, PlGF or IGF-1 concentration between pregnant and non-pregnant women. Spearman correlation analysis revealed a positive correlation between IGF-1 concentration and β-hCG level in pregnant participants (rs = 0.490, p = 0.013). In conclusion, serum IGF-1 level correlated positively with β-hCG level in pregnant women, which may provide information on the prognostic value of IGF-1 in this group of women.

Accuracy of placental growth factor alone or in combination with soluble fms-like tyrosine kinase-1 or maternal factors in detecting preeclampsia in asymptomatic women in the second and third trimesters: a systematic review and meta-analysis

OBJECTIVE

This study aimed to: (1) identify all relevant studies reporting on the diagnostic accuracy of maternal circulating placental growth factor) alone or as a ratio with soluble fms-like tyrosine kinase-1), and of placental growth factor-based models (placental growth factor combined with maternal factors±other biomarkers) in the second or third trimester to predict subsequent development of preeclampsia in asymptomatic women; (2) estimate a hierarchical summary receiver-operating characteristic curve for studies reporting on the same test but different thresholds, gestational ages, and populations; and (3) select the best method to screen for preeclampsia in asymptomatic women during the second and third trimester of pregnancy by comparing the diagnostic accuracy of each method.

DATA SOURCES

A systematic search was performed through MEDLINE, Embase, CENTRAL, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform databases from January 1, 1985 to April 15, 2021.

STUDY ELIGIBILITY CRITERIA

Studies including asymptomatic singleton pregnant women at >18 weeks' gestation with risk of developing preeclampsia were evaluated. We included only cohort or cross-sectional test accuracy studies reporting on preeclampsia outcome, allowing tabulation of 2×2 tables, with follow-up available for >85%, and evaluating performance of placental growth factor alone, soluble fms-like tyrosine kinase-1- placental growth factor ratio, or placental growth factor-based models. The study protocol was registered on the International Prospective Register Of Systematic Reviews (CRD 42020162460).

METHODS

Because of considerable intra- and interstudy heterogeneity, we computed the hierarchical summary receiver-operating characteristic plots and derived diagnostic odds ratios, β, θi, and Λ for each method to compare performances. The quality of the included studies was evaluated by the QUADAS-2 tool.

RESULTS

The search identified 2028 citations, from which we selected 474 studies for detailed assessment of the full texts. Finally, 100 published studies met the eligibility criteria for qualitative and 32 for quantitative syntheses. Twenty-three studies reported on performance of placental growth factor testing for the prediction of preeclampsia in the second trimester, including 16 (with 27 entries) that reported on placental growth factor test alone, 9 (with 19 entries) that reported on the soluble fms-like tyrosine kinase-1-placental growth factor ratio, and 6 (16 entries) that reported on placental growth factor-based models. Fourteen studies reported on performance of placental growth factor testing for the prediction of preeclampsia in the third trimester, including 10 (with 18 entries) that reported on placental growth factor test alone, 8 (with 12 entries) that reported on soluble fms-like tyrosine kinase-1-placental growth factor ratio, and 7 (with 12 entries) that reported on placental growth factor-based models. For the second trimester, Placental growth factor-based models achieved the highest diagnostic odds ratio for the prediction of early preeclampsia in the total population compared with placental growth factor alone and soluble fms-like tyrosine kinase-1-placental growth factor ratio (placental growth factor-based models, 63.20; 95% confidence interval, 37.62-106.16 vs soluble fms-like tyrosine kinase-1-placental growth factor ratio, 6.96; 95% confidence interval, 1.76-27.61 vs placental growth factor alone, 5.62; 95% confidence interval, 3.04-10.38); placental growth factor-based models had higher diagnostic odds ratio than placental growth factor alone for the identification of any-onset preeclampsia in the unselected population (28.45; 95% confidence interval, 13.52-59.85 vs 7.09; 95% confidence interval, 3.74-13.41). For the third trimester, Placental growth factor-based models achieved prediction for any-onset preeclampsia that was significantly better than that of placental growth factor alone but similar to that of soluble fms-like tyrosine kinase-1-placental growth factor ratio (placental growth factor-based models, 27.12; 95% confidence interval, 21.67-33.94 vs placental growth factor alone, 10.31; 95% confidence interval, 7.41-14.35 vs soluble fms-like tyrosine kinase-1-placental growth factor ratio, 14.94; 95% confidence interval, 9.42-23.70).

CONCLUSION

Placental growth factor with maternal factors ± other biomarkers determined in the second trimester achieved the best predictive performance for early preeclampsia in the total population. However, in the third trimester, placental growth factor-based models had predictive performance for any-onset preeclampsia that was better than that of placental growth factor alone but similar to that of soluble fms-like tyrosine kinase-1-placental growth factor ratio. Through this meta-analysis, we have identified a large number of very heterogeneous studies. Therefore, there is an urgent need to develop standardized research using the same models that combine serum placental growth factor with maternal factors ± other biomarkers to accurately predict preeclampsia. Identification of patients at risk might be beneficial for intensive monitoring and timing delivery.

Circulating biomarkers associated with placental dysfunction and their utility for predicting fetal growth restriction

Fetal growth restriction (FGR) leading to low birth weight (LBW) is a major cause of neonatal morbidity and mortality worldwide. Normal placental development involves a series of highly regulated processes involving a multitude of hormones, transcription factors, and cell lineages. Failure to achieve this leads to placental dysfunction and related placental diseases such as pre-clampsia and FGR. Early recognition of at-risk pregnancies is important because careful maternal and fetal surveillance can potentially prevent adverse maternal and perinatal outcomes by judicious pregnancy surveillance and careful timing of birth. Given the association between a variety of circulating maternal biomarkers, adverse pregnancy, and perinatal outcomes, screening tests based on these biomarkers, incorporating maternal characteristics, fetal biophysical or circulatory variables have been developed. However, their clinical utility has yet to be proven. Of the current biomarkers, placental growth factor and soluble fms-like tyrosine kinase 1 appear to have the most promise for placental dysfunction and predictive utility for FGR.

Higher PAPP-A Values in Pregnant Women Complicated with Preeclampsia Than with Gestational Hypertension

The purpose of this study is to compare the levels of maternal serum pregnancy-associated plasma protein-A at the first trimester in pregnancies complicated by impaired placental diseases, such as preeclampsia (PE), intrauterine fetal growth restriction (IUGR), and gestational hypertension (GH), with those in pregnancies without the development of any of these outcomes to expand the knowledge of how this protein behaves in the different impaired placental diseases. This current work is an observational study based on a prospective cohort. Pregnancy-associated plasma protein-A was measured in 422 patients who had completed maternal-perinatal outcomes. Comparisons of pregnancy characteristics and the biomarker between outcome groups (PE, IUGR, gestational hypertension, and not impaired placental outcomes) were analyzed. PAPP-A MoM in the IUGR (0.8 IQR: 0.6-0.9) and GH groups (0.5 IQR: 0.3-1.4) compared to the PE group (1.06 IQR: 0.66-1.52) was significantly lower (p < 0.005). Pregnant women who developed early-onset PE (1.11 IQR 1.08-1.18) presented significant differences with the IUGR group (0.83 IQR: 0.59-0.98; p = 0.002) and those who developed preterm-PE (1.19 IQR: 0.66-1.58; p = 0.045). The results demonstrate that the levels of PAPP-A at first trimester in the sample of women who developed PE, and specially term-PE, were higher than those in women who developed GH or IUGR. The GH group had the lowest PAPP-A values in this sample of pregnant women. Research in a population with a high prevalence of preeclampsia is still lacking and deserves more extended studies to define if these patients could have different rates of PAPP-A.

Perspectives on the Use of Placental Growth Factor (PlGF) in the Prediction and Diagnosis of Pre-Eclampsia: Recent Insights and Future Steps

Pre-eclampsia (PE) is a complex multisystem disease of pregnancy that is becoming increasingly recognized as a state of angiogenic imbalance characterized by low concentrations of placental growth factor (PlGF) and elevated soluble fms-like tyrosine kinase (sFlt-1). PlGF is a protein highly expressed by the placenta with vasculogenic and angiogenic properties, which has a central role in spiral artery remodeling and the development of a low-resistance placental capillary network. PlGF concentrations are significantly lower in women with preterm PE, and these reduced levels have been shown to precede the clinical onset of disease. Subsequently, the clinical utility of maternal serum PlGF has been extensively studied in singleton gestations from as early as 11 to 13 weeks' gestation, utilizing a validated multimarker prediction model, which performs superiorly to the National Institute for Health and Care Excellence (NICE) and American College of Obstetricians and Gynecologists (ACOG) guidelines in the detection of preterm PE. There is extensive research highlighting the role of PlGF-based testing utilizing commercially available assays in accelerating the diagnosis of PE in symptomatic women over 20 weeks' gestation and predicting time-to-delivery, allowing individualized risk stratification and appropriate antenatal surveillance to be determined. "Real-world" data has shown that interpretation of PlGF-based test results can aid clinicians in improving maternal outcomes and a growing body of evidence has implied a role for sFlt-1/PlGF in the prognostication of adverse pregnancy and perinatal events. Subsequently, PlGF-based testing is increasingly being implemented into obstetric practice and is advocated by NICE. This literature review aims to provide healthcare professionals with an understanding of the role of angiogenic biomarkers in PE and discuss the evidence for PlGF-based screening and triage. Prospective studies are warranted to explore if its implementation significantly improves perinatal outcomes, explore the value of repeat PlGF testing, and its use in multiple pregnancies.

Transcriptomic mapping of the metzincin landscape in human trophoblasts

The metzincin family of metalloproteases coordinates tissue developmental processes through regulation of growth factor availability, receptor signaling, and cell-cell/cell-matrix adhesion. While roles for select metzincins in controlling trophoblast functions in human placental development have been described, a comprehensive understanding of metzincin dynamics during trophoblast differentiation is lacking. To address this knowledge gap, single cell transcriptomic datasets derived from first trimester chorionic villi and decidua were used to decipher metzincin expression profiles and kinetics in diverse cell types within the utero-placental interface. Further, specific protease-substrate interactions within progenitor trophoblasts were examined to better define the progenitor niche. Within the uterine-placental compartment, 43 metzincin proteases were expressed across 15 cell-type clusters. Metzincin subgroups expressed in placental trophoblasts, placental mesenchymal cells, uterine stromal, and immune cells included multiple matrix metalloproteases (MMPs), a disintegrin and metalloproteases (ADAMs), a disintegrin and metalloproteases with thrombospondin repeats (ADAMTSs), pappalysins, and astacins. Within the trophoblast compartment, eight distinct trophoblasts states were identified: four cytotrophoblast (CTB), one syncytiotrophoblast precursor (SCTp), two column CTB (cCTB), and one extravillous trophoblast (EVT). Within these states 7 MMP, 8 ADAM, 4 ADAMTS, 2 pappalysin, and 3 astacin proteases were expressed. Cell trajectory modeling shows that expression of most (19/24) metzincins increase during EVT differentiation, though expression of select metalloproteases increase along the villous pathway. Eleven metzincins (ADAM10, -17, MMP14, -15, -19, -23B, ADAMTS1, -6, -19, TLL-1, -2) showed enrichment within CTB progenitors, and analysis of metzincin-substrate interactions identified ∼150 substrates and binding partners, including FBN2 as an ADAMTS6-specific substrate. Together, this work characterizes the metzincin landscape in human first trimester trophoblasts and establishes insight into the roles specific proteases perform within distinct trophoblast niches and across trophoblast differentiation. This resource serves as a guide for future investigations into the roles of metzincin proteases in human placental development.

Is Maternal Cardiovascular Performance Impaired in Altitude-Associated Fetal Growth Restriction?

Mundo, William, Lilian Toledo-Jaldin, Alexandrea Heath-Freudenthal, Jaime Huayacho, Litzi Lazo-Vega, Alison Larrea-Alvarado, Valquiria Miranda-Garrido, Rodrigo Mizutani, Lorna G. Moore, Any Moreno-Aramayo, Richard Gomez, Patricio Gutierrez, and Colleen G. Julian. Is maternal cardiovascular performance impaired in altitude-associated fetal growth restriction? High Alt Med Biol. 23:352-360, 2022. Introduction: The incidence of fetal growth restriction (FGR) is elevated in high-altitude resident populations. This study aims to determine whether maternal central hemodynamics during the last trimester of pregnancy are altered in high-altitude FGR. Methods: In this cross-sectional study of maternal-infant pairs (FGR, n = 27; controls, n = 26) residing in La Paz, Bolivia, maternal heart rate, cardiac output (CO), stroke volume, and systemic vascular resistance (SVR) were assessed using continuous-wave Doppler ultrasound. Transabdominal Doppler ultrasound was used for uterine artery (UtA) resistance indices and fetal measures. Maternal venous soluble fms-like tyrosine kinase-1 (sFlt1) levels were measured. Results: FGR pregnancies had reduced CO, elevated SVR and UtA resistance, fetal brain sparing, and increased maternal sFlt1 versus controls. Maternal SVR was positively associated with UtA resistance and inversely associated with middle cerebral artery resistance and birth weight. Maternal sFlt1 was greater in FGR than controls and positively associated with UtA pulsatility index. Women with elevated sFlt1 levels also tended to have lower CO and higher SVR. Conclusion: Noninvasive assessment of maternal cardiovascular function may be an additional method for detecting high-risk pregnancies at high altitudes, thereby informing the need for increased surveillance and appropriate allocation of resources to minimize adverse outcomes.

sFlt-1/PlGF Ratio Is Not a Good Predictor of Severe COVID-19 nor of Adverse Outcome in Pregnant Women with SARS-CoV-2 Infection-A Case-Control Study

BACKGROUND

Elevated serum levels of sFlt-1 were found in non-pregnant severe COVID-19 patients. The aim was to investigate sFlt-1/PlGF ratio as a predictor of severe disease and adverse outcome in pregnant women with COVID-19.

METHODS

A single-center case-control study was conducted in pregnant women with SARS-CoV-2 infection. SARS-CoV-2-negative pregnant women served as controls. Serum sFlt-1/PlGF ratio was assessed. The primary outcome was severe COVID-19 and the secondary outcome comprised adverse outcomes including severe COVID-19, intensive care unit admission, maternal multiple organ failure, preterm delivery, fetal demise, preeclampsia or hypertension diagnosed after COVID-19, maternal death.

RESULTS

138 women with SARS-CoV-2 infection and 140 controls were included. sFlt-1/PlGF ratio was higher in infected patients (11.2 vs. 24; p < 0.01) and in women with severe disease (50.8 vs. 16.2; p < 0.01). However, it was similar in women with adverse and non-adverse outcome (29.8 vs. 20; p = 0.2). The AUC of sFlt-1/PlGF ratio was 0.66 (95% CI 0.56-0.76) for the prediction of severe COVID-19, and 0.72 (95% CI 0.63-0.79) for the prediction of adverse outcome.

CONCLUSIONS

sFlt-1 and sFlt-1/PlGF ratio are related to SARS-CoV-2 infection and the severity of COVID-19 during pregnancy. However, sFlt-1/PlGF ratio is not a good predictor of severe COVID-19 or adverse outcome.

microRNA signatures associated with fetal growth restriction: a systematic review

Placental-origin microRNA (miRNA) profiles can be useful toward early diagnosis and management of fetal growth restriction (FGR) and associated complications. We conducted a systematic review to identify case-control studies that have examined miRNA signatures associated with human FGR. We systematically searched PubMed and ScienceDirect databases for relevant articles and manually searched reference lists of the relevant articles till May 18th, 2021. Of the 2133 studies identified, 21 were included. FGR-associated upregulation of miR-210 and miR-424 and downregulation of a placenta-specific miRNA cluster miRNA located on C19MC (miR-518b, miR-519d) and miR-221-3p was reported by >1 included studies. Analysis of the target genes of these miRNA as well as pathway analysis pointed to the involvement of angiogenesis and growth signaling pathways, such as the phosphatidylinositol 3-kinase- protein kinase B (PI3K-Akt) pathway. Only 3 out of the 21 included studies reported FGR-associated miRNAs in matched placental and maternal blood samples. We conclude that FGR-associated placental miRNAs could be utilized to inform clinical practice towards early diagnosis of FGR, provided enough evidence from studies on matched placental and maternal blood samples become available.Prospective Register of Systematic Reviews (PROSPERO) registration number: CRD42019136762.

The Pivotal Role of the Placenta in Normal and Pathological Pregnancies: A Focus on Preeclampsia, Fetal Growth Restriction, and Maternal Chronic Venous Disease

The placenta is a central structure in pregnancy and has pleiotropic functions. This organ grows incredibly rapidly during this period, acting as a mastermind behind different fetal and maternal processes. The relevance of the placenta extends far beyond the pregnancy, being crucial for fetal programming before birth. Having integrative knowledge of this maternofetal structure helps significantly in understanding the development of pregnancy either in a proper or pathophysiological context. Thus, the aim of this review is to summarize the main features of the placenta, with a special focus on its early development, cytoarchitecture, immunology, and functions in non-pathological conditions. In contraposition, the role of the placenta is examined in preeclampsia, a worrisome hypertensive disorder of pregnancy, in order to describe the pathophysiological implications of the placenta in this disease. Likewise, dysfunction of the placenta in fetal growth restriction, a major consequence of preeclampsia, is also discussed, emphasizing the potential clinical strategies derived. Finally, the emerging role of the placenta in maternal chronic venous disease either as a causative agent or as a consequence of the disease is equally treated.

A machine-learning-based algorithm improves prediction of preeclampsia-associated adverse outcomes

BACKGROUND

Preeclampsia presents a highly prevalent burden on pregnant women with an estimated incidence of 2% to 5%. Preeclampsia increases the maternal risk of death 20-fold and is one of the main causes of perinatal morbidity and mortality. Novel biomarkers, such as soluble fms-like tyrosine kinase-1 and placental growth factor in addition to a wide span of conventional clinical data (medical history, physical symptoms, laboratory parameters, etc.), present an excellent basis for the application of early-detection machine-learning models.

OBJECTIVE

This study aimed to develop, train, and test an automated machine-learning model for the prediction of adverse outcomes in patients with suspected preeclampsia.

STUDY DESIGN

Our real-world dataset of 1647 (2472 samples) women was retrospectively recruited from women who presented to the Department of Obstetrics at the Charité - Universitätsmedizin Berlin, Berlin, Germany, between July 2010 and March 2019. After standardization and data cleaning, we calculated additional features regarding the biomarkers soluble fms-like tyrosine kinase-1 and placental growth factor and sonography data (umbilical artery pulsatility index, middle cerebral artery pulsatility index, mean uterine artery pulsatility index), resulting in a total of 114 features. The target metric was the occurrence of adverse outcomes throughout the remaining pregnancy and 2 weeks after delivery. We trained 2 different models, a gradient-boosted tree and a random forest classifier. Hyperparameter training was performed using a grid search approach. All results were evaluated via a 10 × 10-fold cross-validation regimen.

RESULTS

We obtained metrics for the 2 naive machine-learning models. A gradient-boosted tree model was performed with a positive predictive value of 88%±6%, a negative predictive value of 89%±3%, a sensitivity of 66%±5%, a specificity of 97%±2%, an overall accuracy of 89%±3%, an area under the receiver operating characteristic curve of 0.82±0.03, an F1 score of 0.76±0.04, and a threat score of 0.61±0.05. The random forest classifier returned an equal positive predictive value (88%±6%) and specificity (97%±1%) while performing slightly inferior on the other available metrics. Applying differential cutoffs instead of a naive cutoff for positive prediction at ≥0.5 for the classifier's results yielded additional increases in performance.

CONCLUSION

Machine-learning techniques were a valid approach to improve the prediction of adverse outcomes in pregnant women at high risk of preeclampsia vs current clinical standard techniques. Furthermore, we presented an automated system that did not rely on manual tuning or adjustments.

Reduced expression in preterm birth of sFLT-1 and PlGF with a high sFLT-1/PlGF ratio in extracellular vesicles suggests a potential biomarker

Preterm birth may have a pathological impact on intrauterine development of the fetal brain, resulting in developmental disabilities. In this study, we examine the expression of soluble Fms-like tyrosine kinase 1 (sFLT-1) and placental growth factor (PlGF), which is one of the vascular endothelial growth factors (VEGFs), as these play a key role in angiogenesis; in particular, we examine their effect on the sFLT-1/PlGF ratio in cases of preterm birth as compared to typical pregnancies. Enzyme-linked immunosorbent assay was performed on samples of maternal-derived plasma and extracellular vesicles-exosomes (EVs-EXs) isolated at the third trimester, consisting of 17 samples from cases of preterm birth and 38 control cases. Our results showed that both sFLT-1 (P=0.0014) and PlGF (P=0.0032) were significantly downregulated in cases of preterm birth compared to controls, while the sFLT-1/PIGF ratio was significantly (P=0.0008) increased in EVs-EXs, but not in maternal plasma. Our results suggest that this reduced expression of sFLT-1 and PlGF with an elevated sFLT-1/PlGF ratio in EVs-EXs may represent a potential biomarker for prediction of PTB.

Circulating EGFL7 distinguishes between IUGR and PE: an observational case-control study

Isolated intrauterine growth restriction (IUGR) and preeclampsia (PE) share common placental pathogenesis. Differently from IUGR, PE is a systemic disorder which may also affect liver and brain. Early diagnosis of these conditions may optimize maternal and fetal management. Aim of this study was to assess whether Epidermal Growth Factor-Like domain 7 (EGFL7) dosage in maternal blood discriminates between isolated IUGR and PE. A total of 116 women were enrolled in this case–control study: 12 non-pregnant women, 34 healthy pregnant women, 34 women presenting with isolated IUGR and 36 presenting with PE. Levels of circulating EGFL7 and other known pro- and anti-angiogenic factors were measured by ELISA at different gestational ages (GA). Between 22–25 weeks of gestation, EGFL7 levels in early-onset PE (e-PE) plasma samples were significantly higher than those measured in controls or isolated IUGR samples (69.86 ± 6.17 vs. 19.8 ± 2.5 or 18.8 ± 2.8 µg/ml, respectively). Between 26–34 weeks, EGFL7 levels remained significantly higher in e-PE compared to IUGR. At term, circulating and placental EGFL7 levels were comparable between IUGR and late-onset PE (l-PE). In contrast, circulating levels of PlGF were decreased in both IUGR- and PE- complicated pregnancies, while levels of both sFLT-1 and sENDOGLIN were increased in both conditions. In conclusion, EGFL7 significantly discriminates between isolated IUGR and PE.

Association of Elevated Maternal Serum Total Bile Acids With Low Birth Weight and Intrauterine Fetal Growth Restriction

IMPORTANCE

Bile acids play essential roles in metabolic modulation. Excessive serum total bile acid (sTBA) levels during pregnancy are associated with adverse perinatal outcomes; however, their association with the risk of intrauterine growth restriction (IUGR) remains unclear.

OBJECTIVE

To investigate the association between maternal sTBA concentration during pregnancy and the risk of IUGR.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included pregnant individuals who delivered live singleton neonates and had regular antenatal examination records available at a hospital-based center in Shanghai, China, from 2014 to 2018. Data were analyzed from July to November 2020.

EXPOSURES

Maternal sTBA concentration during pregnancy.

MAIN OUTCOMES AND MEASURES

Fetal birth weight and probability of low birth weight (LBW) and IUGR.

RESULTS

This study included 68 245 singleton pregnancies with live births for analysis. The mean (SD) age of the pregnant individuals was 30.5 (3.8) years, 67 168 patients (98.4%) were Han, and 50 155 (73.5%) were nulliparous. Nonlinear regression models suggested that there was an inverted J-shaped association between maternal sTBA level during pregnancy and fetal birth weight, with a steep decrease in birth weight at high sTBA levels (estimated mean [SE] birth weight for sTBA of 40.8 ug/mL, 2879 [39.9] g) and greater birth weights at lower sTBA levels (estimated mean [SE] birth weight for sTBA 0.4 μg/mL, 3290 [3.9] g; and for 4.1 μg/mL, 3334 [1.6] g). Lower birth weight and a higher incidence of IUGR were observed in patients with gestational hypercholanemia (sTBA ≥4.08 μg/mL) compared with those without gestational hypercholanemia (birth weight: estimated adjusted mean [SE], 3309 [3.32] vs 3338 [0.80] g; P = .005; incidence of IUGR: 62 of 4467 [1.4%] vs 312 of 63 778 [0.5%]; P < .001). Moreover, compared with patients with sTBA concentrations of less than 4.08 μg/mL, those with gestational hypercholanemia had an increased risk of LBW (adjusted odds ratio [aOR], 1.29; 95% CI, 1.09-1.53) and IUGR (aOR, 2.18; 95% CI, 1.62-2.91). In addition, there was an additive interaction between hypertensive disorders in pregnancy (HDP) and hypercholanemia on LBW and IUGR risk. The highest risks of LBW and IUGR were found in pregnant individuals with both HDP and hypercholanemia compared with those with normotensive pregnancies with sTBA concentrations less than 4.08 μg/mL (LBW: aOR, 9.13; 95% CI, 6.88-12.12; IUGR: aOR, 19.14; 95% CI, 12.09-30.28).

CONCLUSIONS AND RELEVANCE

This study found that gestational hypercholanemia was associated with an increased risk of LBW and IUGR, especially in pregnant individuals with HDP. Therefore, it would be meaningful to monitor sTBA concentration during the follow-up of pregnancies with potential IUGR.

sFlt-1, Not PlGF, Is Related to Twin Gestation Choronicity in the First and Third Trimesters of Pregnancy

Background: Preeclampsia occurs more often in dichorionic than in monochorionic twin pregnancy. We hypothesize that serum concentrations of biomarkers: placental growth factor (PlGF), serum soluble fms-like tyrosine kinase-1 (sFlt-1), and endoglin (Eng) differ between monochorionic and dichorionic twin pregnancies. Methods: A prospective observational study including 43 monochorionic and 36 dichorionic twin gestation was conducted. Blood samples were collected twice from all participants: between 11 + 0 and 13 + 6 and between 32 + 0 and 34 + 0 weeks of gestation. PlGF, sFlt-1 and Eng were measured using immnunoenzymatic assays. Results: We found a significantly higher concentration of sFlt-1 in dichorionic in comparison to monochorionic pregnancies in both the first and third trimesters. PlGF and sEng levels did not differ between mono- and dichorionic gestation in both study periods. sFlt-1 level was related to twin gestation chorionicity, while PlGF expression was not. PlGF, sFlt-1 and sEng concentrations increased significantly during gestation and were much higher in the third trimester compared to the values measured in the first trimester. Conclusions: Angiogenic biomarkers expression differ between dichorionic and monochorionic twin pregnancy. The sFlt-1 level is related to chorionicity of a twin gestation.

Growth arrest-specific protein-6/AXL signaling induces preeclampsia in rats†

Preeclampsia (PE) is a complicated obstetric complication characterized by increased blood pressure, decreased trophoblast invasion, and inflammation. The growth arrest-specific 6 (Gas6) protein is known to induce dynamic cellular responses and is elevated in PE. Gas6 binds to the AXL tyrosine kinase receptor and AXL-mediated signaling is implicated in proliferation and migration observed in several tissues. Our laboratory utilized Gas6 to induce preeclamptic-like conditions in pregnant rats. Our objective was to determine the role of Gas6/AXL signaling as a possible model of PE. Briefly, pregnant rats were divided into three groups that received daily intraperitoneal injections (from gestational day 7.5 to 17.5) of phosphate buffered saline (PBS), Gas6, or Gas6 + R428 (an AXL inhibitor administered from gestational day 13.5 to 17.5). Animals dispensed Gas6 experienced elevated blood pressure, increased proteinuria, augmented caspase-3-mediated placental apoptosis, and diminished trophoblast invasion. Gas6 also enhanced expression of several PE-related genes and a number of inflammatory mediators. Gas6 further enhanced placental oxidative stress and impaired mitochondrial respiration. Each of these PE-related characteristics was ameliorated in dams and/or their placentae when AXL inhibition by R428 occurred in tandem with Gas6 treatment. We conclude that Gas6 signaling is capable of inducing PE and that inhibition of AXL prevents disease progression in pregnant rats. These results provide insight into pathways associated with PE that could be useful in the clarification of potential therapeutic approaches.

Placental secretome characterization identifies candidates for pregnancy complications

Alterations in maternal physiological adaptation during pregnancy lead to complications, including abnormal birthweight and gestational diabetes. Maternal adaptations are driven by placental hormones, although the full identity of these is lacking. This study unbiasedly characterized the secretory output of mouse placental endocrine cells and examined whether these data could identify placental hormones important for determining pregnancy outcome in humans. Secretome and cell peptidome analyses were performed on cultured primary trophoblast and fluorescence-activated sorted endocrine trophoblasts from mice and a placental secretome map was generated. Proteins secreted from the placenta were detectable in the circulation of mice and showed a higher relative abundance in pregnancy. Bioinformatic analyses showed that placental secretome proteins are involved in metabolic, immune and growth modulation, are largely expressed by human placenta and several are dysregulated in pregnancy complications. Moreover, proof-of-concept studies found that secreted placental proteins (sFLT1/MIF and ANGPT2/MIF ratios) were increased in women prior to diagnosis of gestational diabetes. Thus, placental secretome analysis could lead to the identification of new placental biomarkers of pregnancy complications.

Use of the angiogenic biomarker profile to risk stratify patients with fetal growth restriction

BACKGROUND

Novel angiogenic biomarker profiles have demonstrated emerging evidence for predicting preeclampsia onset, severity, and adverse outcomes. Limited data exist in screening patients with fetal growth restriction for preeclampsia development using angiogenic biomarkers.

OBJECTIVE

The objective of this study was to risk stratify patients with fetal growth restriction using a soluble fms-like tyrosine kinase-1 to placental growth factor ratio. Previously published cutoff of 38 was used to predict preeclampsia development and severity as well as adverse maternal or neonatal outcomes within a 2-week time period.

STUDY DESIGN

This was a prospective observational cohort study performed in a single tertiary hospital. Patients with a singleton fetal growth restriction pregnancy between 24 and 37 weeks' gestation were evaluated using serial 2-week encounters from the time of enrollment to delivery. Pregnancies with proven genetic or infectious etiology of fetal growth restriction or congenital anomalies were excluded. Ultrasound growth and Doppler measurements were obtained at the start of every encounter with routine preeclampsia laboratory tests and blood pressure checks when clinically indicated. Maternal serum was collected for all serial encounters and measured for soluble fms-like tyrosine kinase-1 and placental growth factor after delivery in a double-blinded fashion. Maternal charts were reviewed for baseline demographic characteristics, pregnancy diagnoses and outcomes, and neonatal outcomes.

RESULTS

A total of 45 patients were enrolled for a total of 77 encounters, with the median (quartile 1, quartile 3) gestational age of the study enrolled at 31.43 (28.14-33.57) weeks. Patients were divided into low-risk (ratio of <38) and high-risk (ratio of ≥38) groups. Baseline characteristics of patients did not show any marked differences, including preeclampsia labs or ultrasound parameters, between the 2 groups. Systolic and diastolic blood pressures upon enrollment were statistically elevated when soluble fms-like tyrosine kinase-1 to placental growth factor ratio was ≥38 (P=.02 and P=.01, respectively). Compared to patients with a low ratio, patients with a high ratio had a greater proportion of preeclampsia diagnosis, higher rates of preterm delivery under 34 and 37 weeks gestation, smaller neonatal birthweight, and a shorter time to delivery from testing to delivery.

CONCLUSION

Among patients with fetal growth restriction, the soluble fms-like tyrosine kinase-1 to placental growth factor ratio may serve as a potential biomarker for identifying at risk patients for developing preeclampsia and subsequently preterm delivery.

Associations of Hypothyroxinemia With Risk of Preeclampsia-Eclampsia and Gestational Hypertension

OBJECTIVE

To investigate the association between hypothyroxinemia and the risk of preeclampsia-eclampsia and gestational hypertension.

DESIGN

Historical cohort study.

METHODS

The study included pregnant individuals who delivered live-born singletons and had at least one thyroid function assessment during pregnancy at a tertiary hospital. Hypothyroxinemia was defined as thyroid-stimulating hormone (TSH) levels within the normal reference range and free thyroxine (FT4) levels lower than the tenth percentile. Risk ratios (RRs) with 95% confidence intervals (95% CIs) for preeclampsia-eclampsia and gestational hypertension between women with and without a diagnosis of hypothyroxinemia during pregnancy were estimated using a generalized estimating equation model.

RESULTS

A total of 59,463 women with live-born singletons were included in the analysis. Logistic regression models with restricted cubic spline suggested that there was a U-shaped association between FT4 levels and preeclampsia-eclampsia risk. Compared with euthyroid women, those with hypothyroxinemia had an increased risk of preeclampsia-eclampsia (RR = 1.16, 95% CI: 1.02-1.31), and the risk increased with the increasing severity of hypothyroxinemia (p for trend < 0.001). Moreover, persistent hypothyroxinemia from the first to second trimesters was associated with an increased risk of preeclampsia-eclampsia (RR = 1.37, 95% CI: 1.03-1.83), especially for women with severe hypothyroxinemia (RR = 1.70, 95% CI: 1.12-2.58). In contrast, there was no association between hypothyroxinemia and gestational hypertension.

CONCLUSION

Our study suggested that hypothyroxinemia was only associated with an increased risk of preeclampsia-eclampsia, especially in women with persistent hypothyroxinemia in the first half of pregnancy. Analyses of the associated risk of gestational hypertension with hypothyroxinemia were not significant.

"Screening for small-for-gestational age neonates at early third trimester in a high-risk population for preeclampsia"

BACKGROUND

Strategies to improve prenatal detection of small-for-gestational age (SGA) neonates are necessary because its association with poorer perinatal outcome. This study evaluated, in pregnancies with first trimester high risk of early preeclampsia, the performance of a third trimester screening for SGA combining biophysical and biochemical markers.

METHODS

This is a prospective longitudinal study on 378 singleton pregnancies identified at high risk of early preeclampsia according to a first trimester multiparametric algorithm with the cutoff corresponding to 15% false positive rate. This cohort included 50 cases that delivered SGA neonates with birthweight < 10th centile (13.2%) and 328 cases with normal birthweight (86.8%). At 27-30 weeks' gestation, maternal weight, blood pressure, estimated fetal weight, mean uterine artery pulsatility index and maternal biochemical markers (placental growth factor and soluble FMS-Like Tyrosine Kinase-1) were assessed. Different predictive models were created to evaluate their performance to predict SGA neonates.

RESULTS

For a 15% FPR, a model that combines maternal characteristics, estimated fetal weight, mean uterine artery pulsatility index and placental growth factor achieved a detection rate (DR) of 56% with a negative predictive value of 92.2%. The area under receiver operating characteristic curve (AUC) was 0.79 (95% confidence interval (CI), 0.72-0.86). The DR of a model including maternal characteristics, estimated fetal weight and mean uterine artery pulsatility index was 54% (AUC, 0.77 (95% CI, 0.70-0.84)). The DR of a model that includes maternal characteristics and placental growth factor achieved a similar performance (DR 56%, AUC 0.75, 95% CI (0.67-0.83)).

CONCLUSIONS

The performance of screening for SGA neonates at early third trimester combining biophysical and biochemical markers in a high-risk population is poor. However, a high negative predictive value could help in reducing maternal anxiety, avoid iatrogenic interventions and propose a specific plan for higher risk patients.

Fetal Growth Restriction - Diagnostic Work-up, Management and Delivery

Fetal or intrauterine growth restriction (FGR/IUGR) affects approximately 5 – 8% of all pregnancies and refers to a fetus not exploiting its genetically determined growth potential. Not only a major cause of perinatal morbidity and mortality, it also predisposes these fetuses to the development of chronic disorders in later life. Apart from the timely diagnosis and identification of the causes of FGR, the obstetric challenge primarily entails continued antenatal management with optimum timing of delivery. In order to minimise premature birth morbidity, intensive fetal monitoring aims to prolong the pregnancy and at the same time intervene, i.e. deliver, before the fetus is threatened or harmed. It is important to note that early-onset FGR (< 32 + 0 weeks of gestation [wks]) should be assessed differently than late-onset FGR (≥ 32 + 0 wks). In early-onset FGR progressive deterioration is reflected in abnormal venous Doppler parameters, while in late-onset FGR this manifests primarily in abnormal cerebral Doppler ultrasound. According to our current understanding, the “optimum” approach for monitoring and timing of delivery in early-onset FGR combines computerized CTG with the ductus venosus Doppler, while in late-onset FGR assessment of the cerebral Doppler parameters becomes more important.

Progress in deciphering trophoblast cell differentiation during human placentation

The maintenance of gestational well-being requires the proper development of both the embryo and the placenta. Placental trophoblast cells are the major building blocks of the developing placenta. Abnormal trophoblast differentiation underpins placental-based pregnancy complications. However, the mechanisms that govern trophoblast differentiation remain largely unclear. Recent studies shed light on several proteins and regulators that are involved in governing trophoblast differentiation. The advancement of new tools and novel technologies, such as the human trophoblast stem cell culture system, 3D placental organoids and single-cell multi-omics, has brought incredible insights to the field. Here we review the current literature, paying particular attention to articles published between 2017 and 2019 that have promoted our understanding of human trophoblast cell differentiation and its roles in pregnancy and its complications. At the same time, we address challenges and questions arising in the field of human placental development and disease.

Tracking placental development in health and disease

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

MR-proANP, a cardiovascular biomarker to predict late-onset preeclampsia and intrauterine growth restricted fetuses

OBJECTIVES

Midregional pro-atrial natriuretic peptide (MR-proANP) is a cardiac biomarker and the maternal serum levels could predict late-onset preeclampsia (PE) or intrauterine growth restriction (IUGR) at third trimester of pregnancy.

METHODS

We measured MR-proANP between 32 and 37 weeks of pregnancy prospectively: 32 patients suffered from PE and 22 developed IUGR. 676 patients exhibited no pregnancy complications.

RESULTS

The median MR-proANP showed significantly higher results in PE (64.9 pmol/l (interquartile range (IQR) 36.3-105.2) and IUGR (59.7 pmol/l (IQR 39.7-163.0) groups compared to controls (38.7 pmol/l (IQR 29.7-49.2). Linear regression analysis showed association between PE and MR-proANP levels (Exp(ß) = 1.56; 95% CI: 1.34-1.81). AUC showed a predictive value for PE (AUC: 0.72) and IUGR (AUC: 0.71).

CONCLUSIONS

Measuring MR-proANP in maternal serum between 32 and 37 weeks of pregnancy could help predicting IUGR and PE diagnosed after 34 week in pregnancy. Thus, we assume that MR-proANP may be an additional biomarker which mirrors the maternal cardiosvascular status next to sFlt-1/PLGF representing the angiogenic status.

Potential Protein Biomarkers for Preeclampsia

To date, the etiology of preeclampsia (PE) has not been clarified and the specific treatment is lacking; hence, early prediction and prevention are very important. Thus, a large number of biomarkers that may be associated with PE have been identified based on proteomics to provide a reference for the prediction of PE and for the understanding of the pathological mechanisms of this disease. This article briefly summarizes the application of proteomics in PE and the potential protein biomarkers to provide a reference for other researchers.

Increased Angiogenesis and Lymphangiogenesis in the Placental Villi of Women with Chronic Venous Disease during Pregnancy

Pregnancy is a period in a woman’s life associated with an increased risk of developing lower extremity chronic venous disease (CVD). Pregnancy-associated CVD is associated with changes in placental villi. We investigated angiogenesis and lymphangiogenesis in the placental villi of women with CVD during pregnancy compared with healthy controls with no history of CVD (HC). An observational, analytical, and prospective cohort study was conducted on 114 women in their third trimester of pregnancy (32 weeks). Sixty-two participants were clinically diagnosed with CVD. In parallel, 52 controls with no history of CVD (HC) were studied. Gene and protein expression of CD31, podoplanin (D2-40), Flt-1, and placental growth factor (PIGF) was analysed by real-time polymerase chain reaction (RT-qPCR) and immunohistochemistry. CD31 and D2-40 gene expression was significantly greater in the placental villi of women with CVD, as were the numbers of vessels positive for CD31 and D2-40. Significantly higher gene and protein expression of Flt-1 and PIGF was observed in the placental villi of women with CVD. Histological analysis showed more placental villi with periodic acid of Schiff (PAS)-positive material in women with CVD. Our results show a connection between pregnancy-associated CVD and leading to higher proangiogenic and lymphangiogenic activity in placental villi.

Combining Biomarkers to Predict Pregnancy Complications and Redefine Preeclampsia: The Angiogenic-Placental Syndrome

Placental dysfunction underlies a spectrum of perinatal pathologies, including preeclampsia and fetal growth restriction. Angiogenesis-related factors, including sFlt-1 (soluble fms-like tyrosine kinase 1) and PlGF (placental growth factor), play an important role in placental dysfunction; altered levels are detectable several weeks before onset of pregnancy complications. In vitro diagnostic tests for these biomarkers can improve early diagnosis and facilitate prediction of maternal and fetal outcomes. We assessed evidence for combining angiogenic biomarkers with other biomarkers or clinical parameters to predict maternal/fetal outcomes in pregnant women with placental dysfunction. Pooled information on placental perfusion (ultrasonography, mean arterial pressure), clinical characteristics, and biomarker levels (PlGF) can improve first-trimester prediction and preeclampsia diagnosis. Angiogenic factors (sFlt-1/PlGF ratio; PlGF alone) with or without clinical characteristics can facilitate second-/third-trimester prediction of early-onset and late-onset preeclampsia. A combination of increased sFlt-1/PlGF ratio and ultrasound can rule out early fetal growth restriction. The sFlt-1/PlGF ratio is also a reliable tool for discriminating between pregnancy-related hypertensive disorders, including superimposed preeclampsia and gestational hypertension. Analysis of angiogenic factors with or without uterine Doppler substantially improves sensitivity and specificity for predicting adverse outcomes and iatrogenic preterm delivery. We propose to extend the American College of Obstetricians and Gynecologists definition of preeclampsia in the future to include the combination of new-onset hypertension and new-onset of altered angiogenic factors (sFlt-1/PlGF ratio or PlGF alone). In summary, altered angiogenic biomarkers indicate placental dysfunction, and their implementation into clinical practice will help reduce the considerable burden of morbidity and mortality associated with adverse pregnancy outcomes as a consequence of angiogenic-placental syndrome.

Maternal Serum Placental Growth Factor, Soluble Fms-Like Tyrosine Kinase-1, and Soluble Endoglin in Twin Gestations and the Risk of Preeclampsia-A Systematic Review

Multiple gestation is one of the key risk factors for the occurrence of preeclampsia (PE). Soluble fms-like tyrosine kinase-1, placental growth factor, and soluble endoglin are molecules involved in the process of angiogenesis with a proven role in the pathogenesis of PE. The aim of the review was to summarize available data on maternal serum levels of the above-mentioned factors and their usefulness in predicting PE in twin pregnancies. Only original research articles written in English were considered eligible. Reviews, chapters, case studies, conference papers, experts’ opinions, editorials, and letters were excluded from the analysis. No publication date limitations were imposed. The systematic literature search using PubMed/MEDLINE, Scopus, Embase, and Cochrane Library databases identified 338 articles, 10 of which were included in the final qualitative analyses. The included studies showed significant differences in maternal serum levels of the discussed factors between women with twin pregnancies with PE and those who did not develop PE, and their promising performance in predicting PE, alone or in combination with other factors. The identification of the most effective algorithms, their prompt introduction to the clinical practice, and further assessment of the real-life performance should become a priority.

Urinary and Serum Angiogenic Markers in Women With Preexisting Diabetes During Pregnancy and Their Role in Preeclampsia Prediction

OBJECTIVE

To determine the correlation between urinary and serum placental growth factor (PlGF) and investigate the predictive value as pregnancy progresses of urinary PlGF compared with serum PlGF, soluble fms-like tyrosine kinase 1 (sFLT-1), and the sFLT-1-to-PlGF ratio for the outcome of preeclampsia in women with preexisting diabetes.

RESEARCH DESIGN AND METHODS

A multicenter prospective cohort study was conducted of 158 women with preexisting insulin-requiring diabetes (41 with type 1 and 117 with type 2). Urinary PlGF and serum PlGF, sFLT-1, and the sFLT-1-to-PlGF ratio were assessed four times (14, 24, 30, and 36 weeks' gestation), and the association with the outcome of preeclampsia was investigated.

RESULTS

A correlation between urinary and serum PlGF was demonstrated from 24 weeks' gestation onward (P < 0.001). At all time points, those who developed preeclampsia had lower serum PlGF levels (P < 0.05), and receiver operating characteristic curves demonstrated that serum PlGF in this cohort performed better than the serum sFLT-1-to-PlGF ratio as a predictive test for preeclampsia. Preconception HbA_1c ≥6.5% (48 mmol/mol) was an important discriminative predictor for preeclampsia (P = 0.01).

CONCLUSIONS

This study prospectively describes the longitudinal changes in urinary PlGF alongside serum angiogenic markers throughout pregnancy in women with preexisting diabetes. We demonstrate correlation between urinary and serum PlGF and that in women with preexisting diabetes in pregnancy, serum PlGF is a better predictor of preeclampsia than the sFLT-1-to-PlGF ratio.

Role of sFlt-1 and PlGF in the screening of small-for-gestational age neonates during pregnancy: A systematic review

Background

Fetal growth restriction, i.e. the restriction of genetically predetermined growth potential due to placental dysfunction, is a major cause of neonatal morbidity and mortality. The consequences of inadequate fetal growth can be life-long, but the risks can be reduced substantially if the condition is identified prenatally. Currently, screening strategies are based on ultrasound detection of a small-for-gestational age fetus and do not take into account the underlying vascular pathology in the placenta. Measurement of maternal circulating angiogenic biomarkers placental growth factor, sFlt-1 (soluble FMS-like tyrosine kinase-1) are increasingly used in studies on fetal growth restriction as they reflect the pathophysiological process in the placenta. However, interpretation of the role of angiogenic biomarkers in prediction of fetal growth restriction is hampered by the varying design, population, timing, assay technique and cut-off values used in these studies.

Methods

We conducted a systematic-review in PubMed (MEDLINE), EMBASE (Ovid) and Cochrane to explore the predictive performance of maternal concentrations of placental growth factor, sFlt-1 and their ratio for fetal growth restriction and small-for-gestational age, at different gestational ages, and describe the longitudinal changes in biomarker concentrations and optimal discriminatory cut-off values.

Results

We included 26 studies with 2514 cases with small-for-gestational age, 27 cases of fetal growth restriction, 582 cases mixed small-for-gestational age/fetal growth restriction and 29,374 reference. The largest mean differences for the two biomarkers and their ratio were found after 26 weeks of gestational age and not in the first trimester. The ROC-AUC varied between 0.60 and 0.89 with sensitivity and specificity matching the different cut-off values or a preset false-positive rate of 10%.

Conclusions

Most of the studies did not make a distinction between small-for-gestational age and fetal growth restriction, and therefore the small-for-gestational age group consists of fetuses with growth restriction and fetuses that are constitutionally normal. The biomarkers can be a valuable screening tool for small-for-gestational age pregnancies, but unfortunately, there is not yet a clear cut-off value to use for screening. More research is needed to see if these biomarkers are sufficiently able to differentiate growth restriction on their own and how these biomarkers in combination with other relevant clinical and ultrasound parameters can be used in clinical routine diagnostics.

Association between the fetal cerebroplacental ratio and biomarkers of hypoxia and angiogenesis in the maternal circulation at term

OBJECTIVES

A low fetal cerebroplacental ratio (CPR) in late pregnancy is a marker of a fetus that has failed to reach its growth potential and is associated with a variety of perinatal and pregnancy complications. It is not known if it is also correlated with aberrations in angiogenic, hypoxia-responsive or inflammatory cytokine levels in the maternal circulation. We investigated if there were any differences in levels of biomarkers of angiogenesis, endothelial cell dysfunction, hypoxia and/or inflammation in term pregnancies with a low fetal CPR compared to controls. We hypothesized that as the CPR is a marker of suboptimal growth, this would be reflected in a shift towards upregulation of hypoxia-responsive factors even in non-small for gestational age fetuses.

STUDY DESIGN

We used Multiplex ELISA to measure a panel of 28 candidate biomarkers of angiogenesis and/or hypoxia in pre-labour maternal plasma from 113 women at term, stratified for CPR <10th centile vs. CPR >10th centile. Plasma levels of the biomarkers were measured using 2 multiplex Luminex assays - a commercially available human angiogenesis/growth factor panel (R&D Systems®), comprising 15 analytes and an in-house custom panel of a further 13 candidate biomarkers.

RESULTS

Of the 28 candidate biomarkers investigated, we found significantly elevated levels of Carbonic Anhydrase 9 and soluble Fms-like tyrosine kinase (Vascular Endothelial Growth Factor Receptor 1), and lower levels of Placental Growth Factor in plasma from women with a low fetal CPR. The soluble Fms-like tyrosine kinase-1/Placental Growth Factor ratio was also markedly elevated in this cohort. We also demonstrated significant inverse correlations between the fetal CPR and Carbonic Anydrase 9, soluble Fms-like tyrosine kinase and Hepatocyte Growth Factor.

CONCLUSIONS

A low fetal CPR is associated with changes in some hypoxia-responsive and angiogenesis factors in the maternal circulation in pregnancies with normally grown fetuses.

Predictive Performance of PlGF (Placental Growth Factor) for Screening Preeclampsia in Asymptomatic Women: A Systematic Review and Meta-Analysis

Preeclampsia is a systemic syndrome that seems to originate from the placenta and is associated with an imbalance between angiogenic factors in the maternal circulation. One of the well-studied and widely used factors is PlGF (placental growth factor), the levels of which drop in women destined to develop preeclampsia. This drop is known to precede the development of actual signs and symptoms of preeclampsia, thus proving to be a useful screening tool in predicting the disease. The literature varies widely in terms of the clinical usefulness of the test. We conducted a meta-analysis to study the predictive accuracy of PlGF in asymptomatic women. Our analysis included 40 studies with 3189 cases of preeclampsia and 89 498 controls. The overall predictive odds ratio of the test was 9 (6-13). Subgroup analysis evaluating various PlGF thresholds demonstrated that the predictive values were highest for PlGF levels between 80 and 120 pg/mL with a high predictive odds ratio of 25 (7-88), a sensitivity of 0.78 (95% CI, 0.67-0.86), a specificity of 0.88 (95% CI, 0.75-0.95), a positive likelihood ratio of 6.3 (95% CI, 2.7-14.7), and a negative likelihood ratio of 0.26 (95% CI, 0.16-0.42). Additionally, the accuracy was higher when the test was performed after 14 weeks of gestation (OR, 10 [7-15]) and for prediction of early onset preeclampsia (OR, 18 [9-37]). We conclude that PlGF is a useful screening tool to predict preeclampsia. Nonetheless, its utility should be judged with caution and randomized controlled trials are warranted to explore if its implementation improves perinatal outcomes in asymptomatic women.

Assessment of the SFlt-1 and sFlt-1/25(OH)D Ratio as a Diagnostic Tool in Gestational Hypertension (GH), Preeclampsia (PE), and Gestational Diabetes Mellitus (GDM)

Background

Placental soluble fms-like tyrosine kinase-1 (sFlt-1), an antagonist of vascular endothelial growth factor, is considered an etiological factor of endothelial damage in pregnancy pathologies. An increase in the sFlt-1 level is associated with alterations of endothelial integrity. In contrast, vitamin D exerts a protective effect and low concentrations of 25(OH)D may have an adverse effect on common complications of pregnancy, such as gestational hypertension (GH), preeclampsia (PE), and gestational diabetes mellitus (GDM). The aim of this study was to analyze the levels of sFlt-1 in Polish women with physiological pregnancies and pregnancies complicated by GH, PE, and GDM. Moreover, we analyzed relationships between the maternal serum sFlt-1 level and the sFlt-1 to 25(OH)D ratio and the risk of GH and PE.

Material and Methods

The study included 171 women with complicated pregnancies; among them are 45 with GH, 23 with PE, and 103 with GDM. The control group was comprised of 36 women with physiological pregnancies. Concentrations of sFl-1 and 25(OH)D were measured before delivery, with commercially available immunoassays.

Results

Women with GH differed significantly from the controls in terms of their serum sFlt-1 levels (5797 pg/ml vs. 3531 pg/ml, p = 0.0014). Moreover, a significant difference in sFlt-1 concentrations was found between women with PE and those with physiological pregnancies (6074 pg/ml vs. 3531 pg/ml, p < 0.0001). GDM did not exert a statistically significant effect on serum sFlt-1 levels. Both logistic regression and ROC analysis demonstrated that elevated concentration of sFlt-1 was associated with greater risk of GH (AUC = 0.70, p = 0.0001) and PE (AUC = 0.82, p < 0.0001). Also, the sFlt-1 to 25(OH)D ratio, with the cutoff values of 652 (AUC = 0.74, p < 0.0001) and 653 (AUC = 0.88, p < 0.0001), respectively, was identified as a significant predictor of GH and PE.

Conclusions

Determination of the sFlt-1/25(OH)D ratio might provide additional important information and, thus, be helpful in the identification of patients with PE and GH, facilitating their qualification for intensive treatment and improving the neonatal outcomes.

The Role of Placental Growth Factor, Soluble Endoglin, and Uterine Artery Diastolic Notch to Predict the Early Onset of Preeclampsia

BACKGROUND:

Reducing maternal mortality is one of the targets in the Millennium Development Goals (MDGs). In a systematic review, 4.6 per cent (95% CI 2.7-8.2) of pregnancies were complicated by preeclampsia worldwide. Preeclampsia occurs in around 10% of pregnancies in the world whereas developing countries contribute more than developed countries. In developing countries, there are 13 cases of preeclampsia in every 1,000 births, whereas in developed countries only 2-3 cases of preeclampsia are found in every 10,000 deliveries. Variations in prevalence among countries reflect, at least in part, differences in the distribution of maternal age and the proportion of nulliparous pregnant women in the population.

AIM:

We aimed to investigate the role of placental growth factor, soluble endoglin, and uterine artery diastolic notch to predict the early onset of preeclampsia.

METHODS:

This study used an analytical study with a nested case-control design. The study was conducted at Bunda Thamrin Hospital, Tanjung Mulia Mitra Medika Hospital, Sundari Hospital and a private clinic, from March to November 2018 with a total sample of 70 research subjects.

RESULTS:

Uterine artery diastolic notch was not found in 50% of subjects. A total of 27 subjects (38.6%) had a unilateral diastolic notch, and 8 subjects (11.4%) had a bilateral diastolic notch. Cut-off point PIGF levels was 441 pg/ml, and Area Under Curve (AUC) 82.5% (95% CI 61.5%-100%), with sensitivity 80% and specificity 87.7%. The levels sEng in this study could not predict the incidence of early-onset preeclampsia (p = 0.113). Combined PlGF and pulsatile index of uterine arteries may predict early onset preeclampsia with sensitivity 40% and specificity 90.77%. From these results, pregnant women o 22-24 weeks of pregnancy, the levels of PlGF and the uterine artery pulsatility index can be a predictor of early-onset preeclampsia. Examination of PlGF levels alone is sufficient as a predictor of early-onset preeclampsia.

CONCLUSION:

From these results, it can be concluded that in pregnant women of 22-24 weeks, the diastolic notches in uterine arteries cannot predict the incidence of early-onset preeclampsia. PlGF levels and pulsatile index of uterine arteries can be used as predictors of early-onset preeclampsia although examination of PlGF levels alone is sufficient as a predictor of early-onset preeclampsia.

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

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