Characterization of the soluble fms-like tyrosine kinase-1 to placental growth factor ratio in pregnancies complicated by fetal growth restriction

Plasma soluble fms-like tyrosine kinase 1 to placental growth factor ratio of 11.5 multiples of median predicts preeclampsia with severe features within 2 weeks of testing

BACKGROUND

Angiogenic imbalances, characterized by an excess of antiangiogenic factors (soluble fms-like tyrosine kinase 1) and reduced angiogenic factors (vascular endothelial growth factor and placental growth factor), contribute to the mechanisms of disease in preeclampsia. The ratio of soluble fms-like tyrosine kinase 1 to placental growth factor has been used as a biomarker for preeclampsia, but the cutoff values may vary with gestational age and assay platform.

OBJECTIVE

This study aimed to compare multiples of the median of the maternal plasma soluble fms-like tyrosine kinase 1 to placental growth factor ratio, soluble fms-like tyrosine kinase 1, placental growth factor, and conventional clinical and laboratory values in their ability to predict preeclampsia with severe features.

STUDY DESIGN

We conducted a cohort study across 18 United States centers involving hospitalized individuals with hypertension between 23 and 35 weeks' gestation. Receiver operating characteristic curve analyses of maternal plasma biomarkers, highest systolic or diastolic blood pressures, and laboratory values at enrollment were performed for the prediction of preeclampsia with severe features. The areas under the curve were compared, and quasi-Poisson regression models were fitted to estimate relative risks. The primary outcome was preeclampsia with severe features within 2 weeks of enrollment. Secondary outcomes were a composite of severe adverse maternal outcomes (elevated liver enzymes, low platelets count, placental abruption, eclampsia, disseminated intravascular coagulation, and pulmonary edema) and a composite of severe adverse perinatal outcomes (birth weight below the third percentile, very preterm birth [<32 weeks' gestation], and fetal or neonatal death).

RESULTS

Of the 543 individuals included in the study, preeclampsia with severe features within 2 weeks was observed in 33.1% (n=180) of them. A receiver operating characteristic curve-derived cutoff of 11.5 multiples of the median for the soluble fms-like tyrosine kinase 1 to placental growth factor plasma ratio provided good sensitivity (90.6%), specificity (76.9%), positive predictive value (66.0%), negative predictive value (94.3%), positive likelihood ratio (3.91), negative likelihood ratio (0.12), and accuracy (81.4%) for preeclampsia with severe features within 2 weeks. This cutoff was used to compare test positive cases (≥ cutoff) and test negative cases (< cutoff). Preeclampsia with severe features (66.0% vs 5.7%; P<.001) and composites of severe adverse maternal (8.11% vs 2.7%; P=.006) or perinatal (41.3% vs 10.14%; P=.001) outcomes within 2 weeks were more frequent in test positive cases than in test negative cases. A soluble fms-like tyrosine kinase 1 to placental growth factor plasma ratio ≥11.5 multiples of the median was independently associated with preeclampsia with severe features (adjusted incidence rate ratio, 9.08; 95% confidence interval, 6.11-14.06; P<.001) and a composite of severe adverse perinatal outcomes (adjusted incidence rate ratio, 9.42; 95% confidence interval, 6.36-14.53; P<.001) but not with a composite of severe adverse maternal outcomes (adjusted incidence rate ratio, 2.20; 95% confidence interval, 0.95-5.54; P=.08). The area under the curve for the soluble fms-like tyrosine kinase 1 to placental growth factor plasma ratio in multiples of the median (0.91; 95% confidence interval, 0.89-0.94) for preeclampsia with severe features within 2 weeks was significantly higher (P<.001 for all comparisons) than either plasma biomarker alone or any other parameter with the exception of absolute soluble fms-like tyrosine kinase 1 to placental growth factor plasma ratio values.

CONCLUSION

A soluble fms-like tyrosine kinase 1 to placental growth factor plasma ratio ≥11.5 multiples of the mean among hospitalized patients with hypertension between 23 and 35 week's gestation predicts progression to preeclampsia with severe features and severe adverse perinatal outcomes within 2 weeks.

Does the use of angiogenic biomarkers for the management of preeclampsia and fetal growth restriction improve outcomes?: Challenging the current status quo

Monitoring and timing of delivery in preterm preeclampsia and fetal growth restriction is one of the biggest challenges in Obstetrics. Finding the optimal time of delivery of these fetuses usually involves a trade-off between the severity of the disease and prematurity. So far, most clinical guidelines recommend the use of a combination between clinical, laboratory and ultrasound markers to guide the time of delivery. Angiogenic biomarkers, especially placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1), have gained significant attention in recent years for their potential role in the prediction and diagnosis of placenta-related disorders including preeclampsia and fetal growth restriction. Another potential clinical application of the angiogenic biomarkers is for the differential diagnosis of patients with chronic kidney disease, as this condition shares similar clinical features with preeclampsia. Consequently, angiogenic biomarkers have been advocated as tools for monitoring and deciding the optimal time of the delivery of fetuses affected by placental dysfunction. In this clinical opinion, we critically review the available literature on PlGF and sFlt-1 for the surveillance and time of the delivery in fetuses affected by preterm preeclampsia and fetal growth restriction. Moreover, we explore the use of angiogenic biomarkers for the differentiation between chronic kidney disease and superimposed preeclampsia.

First Trimester Placental Biomarkers for Pregnancy Outcomes

The placenta plays a key role in several adverse obstetrical outcomes, such as preeclampsia, intrauterine growth restriction and gestational diabetes mellitus. The early identification of at-risk pregnancies could significantly improve the management, therapy and prognosis of these pregnancies, especially if these at-risk pregnancies are identified in the first trimester. The aim of this review was to summarize the possible biomarkers that can be used to diagnose early placental dysfunction and, consequently, at-risk pregnancies. We divided the biomarkers into proteins and non-proteins. Among the protein biomarkers, some are already used in clinical practice, such as the sFLT1/PLGF ratio or PAPP-A; others are not yet validated, such as HTRA1, Gal-3 and CD93. In the literature, many studies analyzed the role of several protein biomarkers, but their results are contrasting. On the other hand, some non-protein biomarkers, such as miR-125b, miR-518b and miR-628-3p, seem to be linked to an increased risk of complicated pregnancy. Thus, a first trimester heterogeneous biomarkers panel containing protein and non-protein biomarkers may be more appropriate to identify and discriminate several complications that can affect pregnancies.

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.

Longitudinal changes of angiogenic factors as a potential predictive tool in women with suspected preeclampsia

OBJECTIVES

To investigate whether longitudinal changes of angiogenic factors (AF) sFlt-1, PlGF, and the sFlt-1/PlGF ratio, measured following identification of symptoms of preeclampsia (PE), could provide complementary information to the isolated measurements used in current clinical practice.

STUDY DESIGN

Retrospective observational study. Sixty women with suspected PE and two AF results measured before gestational week (GW) 34 were included. Daily variation (DV) of AF was calculated from delta values and days elapsed between measurements. Through ROC analysis, the predictive performance of DV for PE-related events was estimated. Kaplan-Meier survival curves resulting from applying cutoff values were assessed.

RESULTS

The sFlt-1, PlGF, and sFlt-1/PlGF ratio baseline levels showed significant differences between women without PE and women who developed early-onset PE (P < 0.001). DV of sFlt-1 and sFlt-1/PlGF ratio increased according to the severity of PE, showing significant differences in both pairs of groups compared (p < 0.001), so they were selected as potential predictors. Higher AUC values resulting from ROC analysis were 0.78 for early-onset PE, 0.88 for early-onset severe PE, 0.79 for occurrence of adverse maternal outcomes, and 0.89 for delivery before 37 GW, with sensitivity and specificity values higher than 0.71 and 0.80, respectively. The Kaplan-Meier analysis yielded significantly different curves (log-rank < 0.05), with shorter time-to-delivery as DV increased.

CONCLUSION

Our results support the existence of a correlation between a progressive PlGF and sFlt-1 imbalance and a more aggressive clinical course of PE, detectable from the finding of PE symptoms. Its monitoring could be a useful predictive tool in women with suspected PE.

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.

Angiogenic growth factors, oxidative stress and haematobiochemical measures as predictors of preeclampsia with and without foetal growth restriction: A case-control study in a Ghanaian population

INTRODUCTION

This study compares the angiogenic growth mediators (AGMs), oxidative stress (OS) and haematobiochemical profile as well as foeto-maternal outcomes of preeclampsia (PE) with and without foetal growth restriction (FGR) and the discriminative potential of these markers for identifying these conditions.

METHODS

This hospital-based case-control study recruited a total of 209 women including 109 PE women without FGR and 48 PE women with FGR as cases whereas 52 normotensive pregnant women were recruited as controls. OS and AGMs and haematobiochemical markers were measured for all participants.

RESULTS

The rates of foetal complications including intrauterine foetal death and foetal distress were more common in PE with FGR than PE without FGR (p < 0.05) but maternal complications were comparable across these groups (p > 0.05). Of the haematobiochemical markers, placental growth factors (PIGF), PIGF/8-Isoprostane, sFlt-1/PIGF (AUC = 0.87, p < 0.001), soluble FMS-tyrosine kinase receptor-1 (sFlt-1) (AUC = 0.85, p < 0.001), total antioxidant capacity, 8-isoprostane (AUC = 0.83, p < 0.001) and lactate dehydrogenase (AUC = 0.70, p < 0.001) were more associated and showed at least an acceptable discrimination for PE with FGR against PE only.

DISCUSSION

The occurrence of FGR in PE patients does not necessarily indicate a severe maternal presentation of the condition but a tendency for adverse foetal outcomes. Cumulative assessment of OS and AGMs may provide diagnostic usefulness for distinguishing PE with and without FGR.

sFlt-1 Levels as a Predicting Tool in Placental Dysfunction Complications in Multiple Pregnancies

BACKGROUND

several studies have demonstrated that angiogenic markers can improve the clinical management of hypertensive disorders (HDs) and fetal growth restriction (FGR) in singleton pregnancies, but few studies have evaluated the performance of these tests in multiple pregnancies. Our aim was to investigate the role of soluble fms-like tyrosine kinase 1 (sFlt-1) in predicting adverse obstetric outcomes in hospitalized multiple pregnancies with HD (preeclampsia/gestational hypertension/uncontrolled chronic hypertension) and/or FGR in one or more fetuses.

METHODS

A retrospective analysis of multiple pregnancies with HD/FGR occurring after the 20th gestational week. Pregnant women were divided into two groups: women with high levels of sFlt-1 and those with low levels of sFlt-1. A value of sFlt-1 greater than or equal to 15,802 pg/mL was considered arbitrarily high, as it is equivalent to two times the 90th percentile expected in an uncomplicated full-term singleton pregnancy based on data from a prospective multicenter study (7901 pg/mL).

RESULTS

The cohort included 39 multiple pregnancies. There were no cases of birth <34 weeks, HELLP syndrome, ICU admission, and urgent cesarean sections for HD/FGR complications reported among women with low levels of sFlt-1.

CONCLUSIONS

A cut-off value of sFlt-1 ≥ 15,802 pg/mL could represent a valuable tool for predicting adverse obstetric outcomes in multiple pregnancies hospitalized for HD/FGR disorders, regardless of gestational age and chorionicity.

Predictive value of the sFlt‑1/PlGF ratio in women with suspected preeclampsia: An update (Review)

Preeclampsia (PE) is a major complication of pregnancy with an incidence rate of 2‑8% and is a leading cause of maternal mortality and morbidity. The various consequences of severe preeclampsia for the fetus, neonate and child include intrauterine growth retardation (IUGR), fetal hypoxia, oligohydramnios, intrauterine fetal demise, increased perinatal mortality and morbidity, neurodevelopmental disorders and even irreversible brain damage (cerebral palsy). A number of studies have demonstrated that differences in maternal serum concentrations of angiogenic factors between preeclampsia and normotensive pregnancies can be used as biomarkers, either alone or in combination with other markers, to predict the development of PE. The presence in the maternal circulation of two proteins of placental origin, placental growth factor (PlGF) and soluble fms‑like tyrosine kinase 1 (sFlt‑1), has been shown to be of clinical value, as the sFlt‑1/PlGF ratio appears to be the optimal predictive tool for the development of PE. The measurement of their concentration in maternal serum in screening models, serves as predictive marker for the development of PE or IUGR later in gestation. However, further research is required to improve its clinical applicability and provide guidelines for its use worldwide to achieve more consistent clinical management of women with PE.

Evolutionary perspective of uteroplacental malperfusion: subjacent insult common to most pregnancy complications

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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.

Literature Review: The sFlt1/PlGF Ratio and Pregestational Maternal Comorbidities: New Risk Factors to Predict Pre-Eclampsia

One of the main causes of maternal and neonatal morbidity and mortality is pre-eclampsia. It is characterized by a high sFlt1/PlGF ratio, according to prior research. Pregestational diseases in mothers may increase the risk of developing pre-eclampsia. Only a few studies have looked at the connection between maternal comorbidities before conception and the sFlt1/PlGF ratio. The most recent information regarding the association between maternal pregestational diseases and the ratio of sFlt1/PlGF is described in this review. The paper also examines current research suggesting that changes in pregnancy hormones and metabolites are related to a high sFlt1/PlGF ratio. Certain maternal disorders have been found to dramatically raise sFlt-1 and sFlt1/PlGF levels, according to an analysis of the literature. There is still debate about the data on the association between the sFlt1/PlGF ratio and maternal disorders such as HIV, acute coronary syndromes, cardiovascular function in the mother between 19 and 23 weeks of pregnancy, thyroid hormones, diabetes, and cancer. Additional research is needed to confirm these findings.

Clinical utility of sFlt-1 and PlGF in screening, prediction, diagnosis and monitoring of pre-eclampsia and fetal growth restriction

Pre-eclampsia (PE) is characterized by placental and maternal endothelial dysfunction, and associated with fetal growth restriction (FGR), placental abruption, preterm delivery and stillbirth. The angiogenic factors soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) are altered in pregnancies complicated by placenta-related disorders. In this Review, we summarize the existing knowledge, examining the performance of maternal PlGF, sFlt-1 and the sFlt-1/PlGF ratio for screening PE, predicting development of PE in the short term, diagnosing PE, monitoring established PE and predicting other placenta-related disorders in singleton pregnancy. We also discuss the performance of PlGF and the sFlt-1/PlGF ratio for predicting PE in twin pregnancy. For first-trimester screening in singleton pregnancy, a more accurate way of identifying high-risk women than current practice is to combine maternal PlGF levels with clinical risk factors and ultrasound markers. Later in pregnancy, the sFlt-1/PlGF ratio has advantages over PlGF because it has a higher pooled sensitivity and specificity for diagnosing and monitoring PE. It has clinical value because it can rule out the development of PE in the 1-4-week period after the test. Once a diagnosis of PE is established, repeat measurement of sFlt-1 and PlGF can help monitor progression of the condition and may inform clinical decision-making regarding the optimal time for delivery. The sFlt-1/PlGF ratio is useful for predicting FGR and preterm delivery, but the association between stillbirth and the angiogenic factors is unclear. The sFlt-1/PlGF ratio can be used to predict PE in twin pregnancy, although different sFlt-1/PlGF ratio cut-offs from those for singleton pregnancy should be applied for optimal performance. In summary, PlGF, sFlt-1 and the sFlt-1/PlGF ratio are useful for screening, diagnosing, predicting and monitoring placenta-related disorders in singleton and twin pregnancy. We propose that tests for these angiogenic factors are integrated more fully into clinical practice.© 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Predictive Model for Preeclampsia Combining sFlt-1, PlGF, NT-proBNP, and Uric Acid as Biomarkers

N-terminal pro-brain natriuretic peptide (NT-proBNP) and uric acid are elevated in pregnancies with preeclampsia (PE). Short-term prediction of PE using angiogenic factors has many false-positive results. Our objective was to validate a machine-learning model (MLM) to predict PE in patients with clinical suspicion, and evaluate if the model performed better than the sFlt-1/PlGF ratio alone. A multicentric cohort study of pregnancies with suspected PE between 24+0 and 36+6 weeks was used. The MLM included six predictors: gestational age, chronic hypertension, sFlt-1, PlGF, NT-proBNP, and uric acid. A total of 936 serum samples from 597 women were included. The PPV of the MLM for PE following 6 weeks was 83.1% (95% CI 78.5−88.2) compared to 72.8% (95% CI 67.4−78.4) for the sFlt-1/PlGF ratio. The specificity of the model was better; 94.9% vs. 91%, respectively. The AUC was significantly improved compared to the ratio alone [0.941 (95% CI 0.926−0.956) vs. 0.901 (95% CI 0.880−0.921), p < 0.05]. For prediction of preterm PE within 1 week, the AUC of the MLM was 0.954 (95% CI 0.937−0.968); significantly greater than the ratio alone [0.914 (95% CI 0.890−0.934), p < 0.01]. To conclude, an MLM combining the sFlt-1/PlGF ratio, NT-proBNP, and uric acid performs better to predict preterm PE compared to the sFlt-1/PlGF ratio alone, potentially increasing clinical precision.

Similar Pro- and Antiangiogenic Profiles Close to Delivery in Different Clinical Presentations of Two Pregnancy Syndromes: Preeclampsia and Fetal Growth Restriction

The purpose of this study was to evaluate serum levels of anti- and pro-angiogenic substances measured using enzyme-linked immunosorbent assays and their ratios in pregnancies complicated by different clinical subsets of placental ischemic syndrome: preeclampsia and/or fetal growth restriction. A prospective case-control study was performed consisting of 77 singleton pregnancies complicated by preeclampsia, preeclampsia with concurrent fetal growth restriction (FGR), and isolated normotensive FGR pairwise matched by gestational age with healthy pregnancies. The entire study cohort was analyzed with respect to adverse pregnancy outcomes that occurred. In all investigated subgroups, placental growth factor (PlGF) was lower and soluble endoglin (sEng), the soluble fms-like tyrosine kinase-1-sFlt-1/PlGF and sFlt-1*sEng/PlGF ratios were higher than in the control group. The differences were most strongly pronounced in the PE with concurrent FGR group and in the sFlt-1/PlGF ratio. The highest sFlt-1 values in preeclamptic patients suggest that this substance may be responsible for reaching the threshold needed for PE to develop as a maternal manifestation of ischemic placental disease. The FGR is characterized by an elevated maternal sFlt-1/PlGF ratio, which boosts at the moment of indicated delivery due to fetal risk. We concluded that angiogenic imbalance is reflective of placental disease regardless of its clinical manifestation in the mother, and may be used as support for the diagnosis and prognosis of FGR.

sFlt-1/PlGF ratio at 24 weeks gestation in twin pregnancies as a predictor of preeclampsia or fetal growth restriction

OBJECTIVE

to elucidate if sFlt-1/PlGF ratio at 24 weeks in twin pregnancies could be useful to select patients who subsequently develop diseases related to placental dysfunction, such as preeclampsia or fetal growth restriction (FGR).

METHODS

prospective study among all twin pregnancies followed up at a tertiary Hospital. The sFlt-1/PlGF ratio was determined at 24 weeks.

RESULTS

a total of 108 patients with a twin gestation were included. Pregnant women who developed preeclampsia and/or FGR displayed a significantly higher sFlt-1/PlGF ratio at 24 weeks, compared to those who did not develop these diseases (20.3 vs 4.3, p=0.002). Mean sFlt-1/PlGF ratio was not significantly different between patients who subsequently developed preeclampsia compared with those that developed FGR (29.8 vs 18.45, p=0.42). An sFlt-1/PlGF ratio ≥17 at 24 weeks is associated with a significant increase in the frequency of preeclampsia (odds ratio, 37.13 [95% confidence interval, 4.78-288.25]; p=0.002), and FGR (odds ratio, 39.58 [95% confidence interval, 6.31-248.17]; p<0.001). The addition of maternal characteristics, and mean pulsatility index of the uterine arteries to the sFlt-1/PlGF ratio at 24 weeks enhance the identification of patients who develop preeclampsia or FGR.

CONCLUSION

sFlt-1/PlGF ratio at 24 weeks in twin pregnancies, combined with mean pulsatility index of the uterine arteries and maternal characteristics, could select patients who develop preeclampsia or FGR. These patients might benefit from a close follow-up in order to avoid maternal-fetal adverse outcomes.

Clinical interpretation and implementation of the sFlt-1/PlGF ratio in the prediction, diagnosis and management of preeclampsia

Preeclampsia is associated with significant morbidity and mortality for mother and baby. Although around 30% of all pregnancies are evaluated for preeclampsia, diagnosis is difficult, especially in patients who have overlying symptoms from other diseases. Discovery of circulating angiogenic factors in the pathogenesis of preeclampsia has been a major advance for both diagnosis and prognosis. The anti-angiogenic factor, soluble fms-like tyrosine kinase 1 (sFlt-1) and the pro-angiogenic factor, placental growth factor (PlGF), can be measured in plasma and serum and are usually reported as a ratio, which specifically relates to the onset and severity of preeclampsia. The sFlt-1/PlGF ratio has a very high negative predictive value in ruling out the development of preeclampsia within 7 days among women with suspected preeclampsia. Currently, there is no clear consensus on the practical use of angiogenic biomarkers in the detection and management of preeclampsia in routine clinical practice. While major international clinical guidelines exist, they do not define which specific parameters signal patient admission, or outpatient evaluation of suspected preeclampsia, and most clinicians follow local practices. Better guidance is needed on risk stratification among women with suspected preeclampsia, as well as among women at high risk for preeclampsia. Prediction of adverse outcomes in women, after the clinical diagnosis of preeclampsia, is also important. This report has been developed following a meeting of international experts and aims to guide clinicians in the management of pregnant women at risk of preeclampsia using the sFlt-1/PlGF ratio test.

Fetal Growth Restriction: Does an Integrated Maternal Hemodynamic-Placental Model Fit Better?

In recent years, a growing interest has arisen regarding the possible relationship between adverse pregnancy outcomes (APOs) and inadequate maternal hemodynamic adaptations to the pregnancy. A possible association between "placental syndromes," such as preeclampsia (PE) and fetal growth restriction (FGR), and subsequent maternal cardiovascular diseases (CVD) later in life has been reported. The two subtypes of FGR show different pathogenetic and clinical features. Defective placentation, due to a poor trophoblastic invasion of the maternal spiral arteries, is believed to play a central role in the pathogenesis of early-onset PE and FGR. Since placental functioning is dependent on the maternal cardiovascular system, a pre-existent or subsequent cardiovascular impairment may play a key role in the pathogenesis of early-onset FGR. Late FGR does not seem to be determined by a primary abnormal placentation in the first trimester. The pathological pathway of late-onset FGR may be due to a primary maternal cardiovascular maladaptation: CV system shows a flat profile and remains similar to those of non-pregnant women. Since the second trimester, when the placenta is already developed and increases its functional request, a hypovolemic state could lead to placental hypoperfusion and to an altered maturation of the placental villous tree and therefore to an altered fetal growth. Thus, this review focalizes on the possible relationship between maternal cardiac function and placentation in the development of both early and late-onset FGR. A better understanding of maternal hemodynamics in pregnancies complicated by FGR could bring various benefits in clinical practice, improving screening and therapeutic tools.

Course of the sFlt-1/PlGF ratio in fetal growth restriction and correlation with biometric measurements, feto-maternal Doppler parameters and time to delivery

Purpose

The study aimed to assess the course of the soluble Fms-like tyrosine kinase 1 (sFlt-1)/placental growth factor (PlGF) ratio in pregnant women with fetal growth restriction (FGR) and to evaluate potential associations between the sFlt-1/PlGF ratio and feto-maternal Doppler parameters, fetal biometric measurements and the time between study inclusion and birth (“time to delivery”).

Methods

This was a retrospective longitudinal single center study including 52 FGR cases. The serum levels of sFlt-1 and PlGF were measured by using the BRAHMS Kryptor Compact PLUS. Fetal biometric and Doppler parameters, as well as the sFlt-1/PlGF ratio, were obtained both upon study inclusion and upon birth.

Results

Various associations between the levels of the biomarkers in maternal blood upon study inclusion and upon birth and sonographic parameters were observed in FGR cases: umbilical artery (p < 0.01), uterine arteries (p < 0.01), ductus venosus (p < 0.05), cerebroplacental ratio (CPR) (p < 0.01), femur length (p < 0.01) and birth weight (p < 0.01). The higher the sFlt-1/PlGF ratio upon study inclusion, the shorter the “time to delivery” (p < 0.01). The multivariate regression analysis showed that the greater the daily percentage increase of the angiogenic markers, the shorter the “time to delivery” (p < 0.01).

Conclusion

The fetal well-being, as measured by feto-maternal Doppler parameters such as CPR and the severity of the placental dysfunction, as measured by the urgency of birth and birth weight, is reflected by the level of the sFlt-1/PlGF ratio in the maternal serum. A rapid daily increase of the sFlt-1/PlGF ratio is significantly associated with the clinical progression of the disease.

Prediction of Adverse Pregnancy Outcome Related to Placental Dysfunction Using the sFlt-1/PlGF Ratio: A Narrative Review

The sFlt-1 (soluble fms-like tyrosine kinase-1)/PlGF (placental growth factor) ratio is a helpful tool for the prediction and diagnosis of preeclampsia (PE). Current data even show that the ratio has the potential to predict adverse pregnancy outcomes (APO) caused by placental pathologies. The aim of this article is to give a brief overview of recent findings on APO predictions based on the sFlt-1/PlGF ratio. The focus is on obstetric pathologies related to placental dysfunction (PD) such as PE and/or fetal growth restriction (FGR). New uses of the sFlt-1/PlGF ratio as a predictor of APO demonstrate its potential with regard to planning hospitalization and corticosteroid administration and the optimal timing of delivery. However, prospective interventional studies are warranted to define the exact role of the sFlt-1/PlGF ratio as a predictor of adverse pregnancy outcomes caused by placental pathologies.

Angiogenic factors and prediction for ischemic placental disease in future pregnancies

OBJECTIVES

Ischemic placental disease (IPD), including preeclampsia, abruption, and fetal growth restriction, often recurs in subsequent pregnancies. Angiogenic factors of placental origin have been implicated in the pathogenesis of preeclampsia, but have not been studied as predictors of IPD in subsequent pregnancies. We hypothesized that elevated angiogenic factors in an index pregnancy would be associated with recurrence of IPD.

STUDY DESIGN

We conducted a retrospective cohort study of patients undergoing evaluation for preeclampsia who had angiogenic factors measured in an index pregnancy and experienced a subsequent pregnancy at the same institution. Patients with IPD in the index pregnancy were included. A high ratio of soluble fms-like tyrosine kinase 1 (sFlt1) and placental growth factor (PlGF) was defined as greater than or equal to 85.

MAIN OUTCOME MEASURES

The primary outcome was IPD in a subsequent pregnancy.

RESULTS

We included 109 patients in the analysis. The sFlt1/PlGF ratio was elevated in 30% of participants. Those with an elevated ratio were more likely to be nulliparous in the index pregnancy, and less likely to have chronic hypertension. The recurrence of IPD in the study was 27%, with a non-significant difference in risk based on a high sFlt-1/P1GF ratio RR 0.58 (95% CI 0.21 - 1.6) compared to a low ratio.

CONCLUSIONS

A high sFlt1/P1GF ratio in an index pregnancy is not associated with a higher risk of IPD in a subsequent pregnancy. These data suggest placental angiogenic biomarkers are specific to the pregnancy and not a reflection of maternal predisposition to IPD.

Comparing fetal biometric growth velocity versus estimated fetal weight for prediction of neonatal small for gestational age

OBJECTIVE

Growth velocities derived from fetal biometrics have been proposed to improve prediction of small for gestational age (SGA) neonates. We sought to determine if ultrasound growth velocities for abdominal circumference (AC) and estimated fetal weight (EFW) improve the prediction of SGA infants when compared to using EFW alone.

STUDY DESIGN

This is a secondary analysis from a prospective study of women referred for growth ultrasounds during the third trimester. Growth velocities for AC and EFW were derived from the difference in Z-scores between measurements at the anatomy survey (18-22 weeks gestation) and later growth ultrasound (26-36 weeks gestation). Change in AC and EFW growth velocities <10th percentile were compared with prenatally suspected SGA from Hadlock EFW <10th percentile for prediction of SGA neonates. The primary outcome was defined as the sensitivity and specificity of the growth velocities and Hadlock EFW in predicting SGA neonates. Logistic regression modeling was used to determine if the growth velocities improved prediction of neonatal SGA. Area under the ROC curves (AUC) were determined and compared.

RESULTS

Of 612 singleton pregnancies meeting inclusion criteria, 68 (11.1%) resulted in SGA neonates. Hadlock EFW <10th percentile had higher sensitivity and specificity when compared to AC growth velocity and EFW growth velocity. Only AC growth velocity and Hadlock EFW had significant odds ratios for association with neonatal SGA. The AUC were 0.54, 0.53, and 0.61 using AC growth velocity, EFW growth velocity, and Hadlock EFW, respectively. The AUC did not significantly improve when the growth velocities were combined with Hadlock EFW (0.63). Adjustment of Z-scores for gestational age at anatomy scan or third trimester growth scan did not significantly change these results (AUC = 0.69).

CONCLUSION

EFW determined by Hadlock formula has the highest predictive value in detecting SGA neonates when compared to both AC and EFW growth velocities.

Comparison of Efficiency and Function of Vascular Endothelial Growth Factor Adenovirus Vectors in Endothelial Cells for Gene Therapy of Placental Insufficiency

Severe fetal growth restriction (FGR) affects 1:500 pregnancies, is untreatable and causes serious neonatal morbidity and death. Reduced uterine blood flow (UBF) and lack of bioavailable VEGF due to placental insufficiency is a major cause. Transduction of uterine arteries in normal or FGR sheep and guinea pigs using an adenovirus (Ad) encoding VEGF isoforms A (Ad.VEGF-A165) and a FLAG-tagged pre-processed short form D (DΔNΔC, Ad.VEGF-DΔNΔC-FLAG) increases endothelial nitric oxide expression, enhances relaxation and reduces constriction of the uterine arteries and their branches. UBF and angiogenesis are increased long term, improving fetal growth in utero. For clinical trial development we compared Ad.VEGF vector transduction efficiency and function in endothelial cells (ECs) derived from different species. We aimed to compare the transduction efficiency and function of the pre-clinical study Ad. constructs (Ad.VEGF-A165, Ad.VEGF-DΔNΔC-FLAG) with the intended clinical trial construct (Ad.VEGF-DΔNΔC) where the FLAG tag is removed. We infected ECs from human umbilical vein, pregnant sheep uterine artery, pregnant guinea pig aorta and non-pregnant rabbit aorta, with increasing multiplicity of infection (MOI) for 24 or 48 hours of three Ad.VEGF vectors, compared to control Ad. containing the LacZ gene (Ad.LacZ). VEGF supernatant expression was analysed by ELISA. Functional assessment used tube formation assay and Erk-Akt phosphorylation by ELISA. VEGF expression was higher after Ad.VEGF-DΔNΔC-FLAG and Ad.VEGF-DΔNΔC transduction compared to Ad.VEGF-A165 in all EC types (*p < 0.001). Tube formation was higher in ECs transduced with Ad.VEGF-DΔNΔC in all species compared to other constructs (***p < 0.001, *p < 0.05 with rabbit aortic ECs). Phospho-Erk and phospho-Akt assays displayed no differences between the three vector constructs, whose effect was, as in other experiments, higher than Ad.LacZ (***p < 0.001). In conclusion, we observed high transduction efficiency and functional effects of Ad.VEGF-DΔNΔC vector with comparability in major pathway activation to constructs used in pre-clinical studies, supporting its use in a clinical trial.

sFlt-1/PlGF ratio and timing of delivery in early-onset fetal growth restriction with antegrade umbilical artery flow

OBJECTIVE

To analyze the value of the soluble fms-like tyrosine kinase-1/placental growth factor (sFlt-1/PlGF) ratio in predicting the time to delivery in early-onset fetal growth restriction (FGR) with preserved antegrade umbilical artery (UA) flow at diagnosis.

METHODS

This was a prospective observational single-center cohort study of pregnancies with early-onset (< 32 + 0 weeks) FGR and antegrade UA flow, in which maternal serum sFlt-1/PlGF ratio was determined at diagnosis. FGR was defined as estimated fetal weight < 3^rd centile or < 10^th centile with UA pulsatility index > 95^th centile, fetal middle cerebral artery pulsatility index < 5^th centile or cerebroplacental ratio < 5^th centile. The previously described sFlt-1/PlGF ratio cut-off value of 85 for facilitating the diagnosis of pre-eclampsia was assessed in the prediction of the need to deliver in < 1 week and ≥ 4 weeks.

RESULTS

In total, 120 cases were included. There were 116 (96.7%) liveborn neonates and 108 (90.0%) perinatal survivors. Median (interquartile range (IQR)) gestational age at diagnosis of early-onset FGR was 27.1 (25.7-29.4) weeks. Median (IQR) sFlt-1/PlGF ratio at diagnosis was 196 (84-474). Ninety (75.0%) cases had a sFlt-1/PlGF ratio ≥ 85. Among pregnancies with a liveborn neonate, median (IQR) interval to delivery in the groups with sFlt-1/PlGF ratio < 85 and ≥ 85 was 41 (22-54) days and 11 (4-20) days, respectively (P < 0.01). The probability of having to deliver within 1 week after diagnosis was 0% and 35.6% in those with sFlt-1/PlGF ratio < 85 and ≥ 85, respectively (P = 0.03), and the probability of delaying delivery for ≥ 4 weeks was 72.4% and 19.5%, respectively (P < 0.01).

CONCLUSION

sFlt-1/PlGF ratio < 85 at diagnosis of early-onset FGR with antegrade UA flow identifies a group of pregnancies in which the need to deliver within 1 week is very low and the interval to delivery is expected to be prolonged for ≥ 4 weeks in > 70% of cases. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Maternal and Perinatal Outcomes Associated With Extremely High Values for the sFlt-1 (Soluble fms-Like Tyrosine Kinase 1)/PlGF (Placental Growth Factor) Ratio

Background There is little knowledge about the significance of extremely high values (>655) for the ratio of sFlt-1 (soluble fms-like tyrosine kinase 1) to PlGF (placental growth factor). We aim to describe the time-to-delivery interval and maternal and perinatal outcomes when such values are demonstrated while assessing suspected or confirmed placental dysfunction based on clinical or sonographic criteria. Methods and Results A multicenter retrospective cohort study was performed on 237 singleton gestations between 20+0 and 37+0 weeks included at the time of first demonstrating a sFlt-1/PlGF ratio >655. Clinicians were aware of this result, but standard protocols were followed for delivery indication. Main outcomes were compared for women with and without preeclampsia at inclusion. In those with preeclampsia (n=185, of whom 77.3% had fetal growth restriction), severe preeclampsia features and fetal growth restriction in stages III or IV were present in 49.2% and 13.5% cases, respectively, at inclusion and in 77.3% and 28.6% cases, respectively, at delivery. In the group without preeclampsia (n=52, 82.7% had fetal growth restriction), these figures were 0% and 30.8%, respectively, at inclusion and 21.2% and 50%, respectively, at delivery. Interestingly, 28% of women without initial preeclampsia developed it later. The median time to delivery was 4 days (interquartile range: 1-6 days) and 7 days (interquartile range: 3-12 days), respectively (P<0.01). Overall, perinatal mortality was 62.1% before 24 weeks; severe morbidity surpassed 50% before 29 weeks but became absent from 34 weeks. Maternal serious morbidity was high at any gestational age. Conclusions An sFlt-1/PlGF ratio >655 is almost invariably associated with preeclampsia or fetal growth restriction that progresses rapidly. In our tertiary care settings, we observed that maternal adverse outcomes were high throughout gestation, whereas perinatal adverse outcomes diminished as pregnancy advanced.

Correlation of Kryptor and Elecsys® immunoassay sFlt-1/PlGF ratio on early diagnosis of preeclampsia and fetal growth restriction: A case-control study

OBJECTIVES

The measurement of the soluble fms-like tyrosine kinase-1 to placental growth factor (sFlt-1/PlGF) ratio on automated platforms has improved the detection of preeclampsia and fetal growth restriction (PE/FGR). The cut-off points of >38 and ≥85 has been defined for "rule in" and "aid in diagnosis", respectively, using the Elecsys® platform. We aimed to compare the performance of these cut-offs between the Elecsys® and Kryptor platforms at 24-28 weeks.

STUDY DESIGN

Observational case-control study of singleton pregnancies at high risk for PE/FGR and sFlt-1/PlGF measurement at 24-28 weeks' gestation: 21 cases (9 early PE/FGR with delivery <32 weeks) were 1:1 matched for body mass index and parity with 21 controls. Correlations of the sFlt-1, PlGF and sFlt-1/PlGF values and diagnostic accuracy of the >38 and ≥85 cutoffs for early and late PE/FGR using Elecsys® and Kryptor assays were evaluated.

MAIN OUTCOME MEASURES

PE/FGR cases showed significantly higher median (IQR) sFlt-1/PlGF values at 24-28 weeks vs. controls, using both Elecsys® and Kryptor platforms: 55 (13-254) and 97 (13-530) vs. 4.1 (2.0-6.5) and 3.9 (1.8-7.7), respectively. The sFlt-1/PlGF correlation between both methods was excellent (r² = 0.95) although lower PlGF and higher sFlt-1/PlGF values were observed with Kryptor. The higher diagnostic accuracy was obtained for early PE/FGR with the ≥85 cutoff (95.2%; 95%CI: 83.8-99.4%) in both platforms.

CONCLUSION

sFlt-1/PlGF measurements correlates well between Elecsys® and Kryptor platforms, and the cutoffs of >38 and ≥85 exhibit high diagnostic accuracy for assessing early PE/FGR at 24-28 weeks with both methods.

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.

Biochemical tests of placental function versus ultrasound assessment of fetal size for stillbirth and small-for-gestational-age infants

BACKGROUND

Stillbirth affects 2.6 million pregnancies worldwide each year. Whilst the majority of cases occur in low- and middle-income countries, stillbirth remains an important clinical issue for high-income countries (HICs) - with both the UK and the USA reporting rates above the mean for HICs. In HICs, the most frequently reported association with stillbirth is placental dysfunction. Placental dysfunction may be evident clinically as fetal growth restriction (FGR) and small-for-dates infants. It can be caused by placental abruption or hypertensive disorders of pregnancy and many other disorders and factorsPlacental abnormalities are noted in 11% to 65% of stillbirths. Identification of FGA is difficult in utero. Small-for-gestational age (SGA), as assessed after birth, is the most commonly used surrogate measure for this outcome. The degree of SGA is associated with the likelihood of FGR; 30% of infants with a birthweight < 10th centile are thought to be FGR, while 70% of infants with a birthweight < 3rd centile are thought to be FGR. Critically, SGA is the most significant antenatal risk factor for a stillborn infant. Correct identification of SGA infants is associated with a reduction in the perinatal mortality rate. However, currently used tests, such as measurement of symphysis-fundal height, have a low reported sensitivity and specificity for the identification of SGA infants.

OBJECTIVES

The primary objective was to assess and compare the diagnostic accuracy of ultrasound assessment of fetal growth by estimated fetal weight (EFW) and placental biomarkers alone and in any combination used after 24 weeks of pregnancy in the identification of placental dysfunction as evidenced by either stillbirth, or birth of a SGA infant. Secondary objectives were to investigate the effect of clinical and methodological factors on test performance.

SEARCH METHODS

We developed full search strategies with no language or date restrictions. The following sources were searched: MEDLINE, MEDLINE In Process and Embase via Ovid, Cochrane (Wiley) CENTRAL, Science Citation Index (Web of Science), CINAHL (EBSCO) with search strategies adapted for each database as required; ISRCTN Registry, UK Clinical Trials Gateway, WHO International Clinical Trials Portal and ClinicalTrials.gov for ongoing studies; specialist abstract and conference proceeding resources (British Library's ZETOC and Web of Science Conference Proceedings Citation Index). Search last conducted in Ocober 2016.

SELECTION CRITERIA

We included studies of pregnant women of any age with a gestation of at least 24 weeks if relevant outcomes of pregnancy (live birth/stillbirth; SGA infant) were assessed. Studies were included irrespective of whether pregnant women were deemed to be low or high risk for complications or were of mixed populations (low and high risk). Pregnancies complicated by fetal abnormalities and multi-fetal pregnancies were excluded as they have a higher risk of stillbirth from non-placental causes. With regard to biochemical tests, we included assays performed using any technique and at any threshold used to determine test positivity.

DATA COLLECTION AND ANALYSIS

We extracted the numbers of true positive, false positive, false negative, and true negative test results from each study. We assessed risk of bias and applicability using the QUADAS-2 tool. Meta-analyses were performed using the hierarchical summary ROC model to estimate and compare test accuracy.

MAIN RESULTS

We included 91 studies that evaluated seven tests - blood tests for human placental lactogen (hPL), oestriol, placental growth factor (PlGF) and uric acid, ultrasound EFW and placental grading and urinary oestriol - in a total of 175,426 pregnant women, in which 15,471 pregnancies ended in the birth of a small baby and 740 pregnancies which ended in stillbirth. The quality of included studies was variable with most domains at low risk of bias although 59% of studies were deemed to be of unclear risk of bias for the reference standard domain. Fifty-three per cent of studies were of high concern for applicability due to inclusion of only high- or low-risk women.Using all available data for SGA (86 studies; 159,490 pregnancies involving 15,471 SGA infants), there was evidence of a difference in accuracy (P < 0.0001) between the seven tests for detecting pregnancies that are SGA at birth. Ultrasound EFW was the most accurate test for detecting SGA at birth with a diagnostic odds ratio (DOR) of 21.3 (95% CI 13.1 to 34.6); hPL was the most accurate biochemical test with a DOR of 4.78 (95% CI 3.21 to 7.13). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.88 and median prevalence of 19%, EFW, hPL, oestriol, urinary oestriol, uric acid, PlGF and placental grading will miss 50 (95% CI 32 to 68), 116 (97 to 133), 124 (108 to 137), 127 (95 to 152), 139 (118 to 154), 144 (118 to 161), and 144 (122 to 161) SGA infants, respectively. For the detection of pregnancies ending in stillbirth (21 studies; 100,687 pregnancies involving 740 stillbirths), in an indirect comparison of the four biochemical tests, PlGF was the most accurate test with a DOR of 49.2 (95% CI 12.7 to 191). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.78 and median prevalence of 1.7%, PlGF, hPL, urinary oestriol and uric acid will miss 2 (95% CI 0 to 4), 4 (2 to 8), 6 (6 to 7) and 8 (3 to 13) stillbirths, respectively. No studies assessed the accuracy of ultrasound EFW for detection of pregnancy ending in stillbirth.

AUTHORS' CONCLUSIONS

Biochemical markers of placental dysfunction used alone have insufficient accuracy to identify pregnancies ending in SGA or stillbirth. Studies combining U and placental biomarkers are needed to determine whether this approach improves diagnostic accuracy over the use of ultrasound estimation of fetal size or biochemical markers of placental dysfunction used alone. Many of the studies included in this review were carried out between 1974 and 2016. Studies of placental substances were mostly carried out before 1991 and after 2013; earlier studies may not reflect developments in test technology.

Intrauterine growth restriction, soluble fms-like tyrosine kinase-1 to placental growth factor ratio increase and preeclampsia

BACKGROUND

Intrauterine growth restriction (IUGR) and preeclampsia (PE) share common features such as ischemic placental disease but also differ in their clinical expression regarding maternal diseases. The reason why IUGRremains isolated in some cases yet is followed by clinical manifestations of PE in other cases remains unexplained.

CASE REPORT

A 40-year old woman, gravida two, para one, experienced early-onset IUGR with a significant increase in the ratio of soluble fms-like tyrosine kinase 1 (sFlt-1) to placental growth factor (PlGF) but, surprisingly, without any maternal clinical manifestations of PE.

CONCLUSION

IUGR and a significant increase in sFlt-1/PlGF ratio without PE raise the issue of a missing factor enabling IUGR, a significant increase in sFlt-1/PlGF ratio, and PE to be linked. TEACHING POINTS: (1) Early-onset IUGR and a significant increase in sFlt-1/PlGF ratio do not necessarily mean the onset of PE. (2) Combining early-onset IUGR and a significant increase in sFlt-1/PlGF ratio without PE raises the question of an additional factor responsible for the onset of PE.

Pilot study: placental biomarker predictive capability (sFlt-1, PlGF and their ratio) of postpartum maternal outcome

BACKGROUND

Prenatal measurement of placental biomarkers was able to improve screening and diagnosis of preeclampsia. Little is known about the clinical role of placental biomarkers in the postpartum period.

METHODS

This study is a prospective monocentric trial that included a total of 30 women with preeclamptic pregnancies. Serum placental biomarkers including soluble fms-like tyrosine kinase 1 (sFlt-1) and placental growth factor (PlGF) were measured before and 2 h after delivery by Enzyme-Linked Immunosorbent Assay (ELISA) using commercially available kits according to manufacturer's instructions and correlated with the postpartum outcome.

RESULTS

Postpartum higher serum PlGF level was associated with postpartum elevation of the systolic blood pressure. Yet, the placental biomarkers were not able to predict general worsening of postpartum preeclampsia or other individual clinical or laboratory parameters.

CONCLUSION

Serum concentrations of sFlt-1 and PlGF or their ratio in our study cohort did not completely predict the occurrence of postpartum preeclampsia. Yet, postpartum higher serum PlGF level was associated with postpartum elevation of the systolic blood pressure.

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.

Changes in intrapartum maternal placental growth factor levels in pregnancies complicated by fetal compromise at term

BACKGROUND

Intrapartum fetal compromise (IFC) may result from the gradual decline in placental function during labour and can precipitate adverse neonatal outcomes. Placental growth factor (PlGF) is a biomarker of placental function. This study aims to investigate maternal PlGF levels and adverse perinatal outcomes in term labour.

METHODS

Prospective observational study (Mater Mothers' Hospital, Brisbane). Eligibility: 37⁺⁰- 42⁺⁰ weeks gestation, singleton, cephalic, non-anomalous pregnancies. Cases of pre-eclampsia and fetal growth restriction were excluded. Maternal PlGF was sampled at the onset of the first stage of labour (1st PlGF) and again at the second stage (2nd PlGF).

RESULTS

Sixty-three participants met inclusion criteria. Women requiring operative delivery (n = 11) for IFC had lower 1st PlGF (90.8 vs. 111.8 pg/ml) and 2nd PlGF (65.8 vs. 83.7 pg/ml) compared to the no-IFC cohort (n = 52). PlGF levels decreased significantly during labour in both the IFC (90.8 vs. 65.8 pg/ml, p = 0.021) and no-IFC (111.8 v 83.7, p < 0.001) cohorts, although the decline in PlGF levels was greater in the IFC cohort (-41.8% vs. -23.4%, p = 0.385). Maternal PlGF levels were significantly lower in those with an abnormal fetal heart rate pattern, cord arterial pH < 7.2, nursery admission and composite adverse neonatal outcome (CANO). PlGF decline was not correlated to duration of labour but was influenced by nulliparity and induced labour.

CONCLUSIONS

Maternal PlGF levels are lower in pregnancies complicated by IFC and CANO, and declines more sharply during labour compared to the no-IFC cohort. The utility of PlGF as a predictor of IFC should be further investigated with clinical trials.

Correlation between uterine artery Doppler and the sFlt-1/PlGF ratio in different phenotypes of placental dysfunction

OBJECTIVE

To explore correlations between the sFlt-1/PlGF ratio and uterine arteries (UtA) Doppler indexes in placental dysfunction-related disorders (PDD).

METHODS

We prospectively included women with a singleton pregnancy with preeclampsia (PE) only (n = 22), preeclampsia with fetal growth restriction (FGR) (n = 32), FGR only (n = 12), or normal pregnancy (n = 29).

RESULTS

In PDDs, significantly positive correlations between the sFlt-1/PlGF ratio and the mean UtA pulsatility (mPI-UtA), as well as the resistance index (mRI-UtA) were found (p = 0.015, p = 0.019, respectively), but not in normal pregnancies. PDD with signs of impaired placentation, evidenced by the increased sFlt-1/PlGF ratio and mPI-UtA, was found in 50.0%, and, by the increased sFlt-1/PlGF ratio and mRI-UtA, in 65.2%. PDD without signs of impaired placentation, evidenced by the increased sFlt-1/PlGF ratio but normal mPI-UtA, was found in 24.2%, and, by the increased sFlt-1/PlGF ratio but normal mRI-UtA, in 7.6%. A substantial proportion of women with signs of impaired placentation were diagnosed with FGR with or without PE.

CONCLUSION

In PDD, the sFlt-1/PlGF ratio and UtA Doppler indexes increase proportionally. Correlations between the sFlt-1/PlGF ratio and UtA Doppler indexes might help to distinguish between PDDs with and without impaired placentation. However, further studies are needed to explore the correlations in different phenotypes of PDD.

Longitudinal change of sFlt-1/PlGF ratio in singleton pregnancy with early-onset fetal growth restriction

OBJECTIVE

To describe the evolution of soluble fms-like tyrosine kinase-1 to placental growth factor (sFlt-1/PlGF) ratio in the last 5 weeks prior to delivery in singleton pregnancy complicated by early-onset fetal growth restriction (FGR), with or without pre-eclampsia (PE).

METHODS

This was a prospective observational cohort study of early-onset FGR cases that underwent serial assessment of maternal serum sFlt-1/PlGF ratio from diagnosis to delivery. Measurements were made at weekly intervals and within the last 48 h before birth. Absolute values and percentage increase between time intervals were computed, and previously described cut-off values of 38 (suspicion of PE), 85 (aids diagnosis of PE) and 655 (high risk for imminent delivery) were used for analysis of the sFlt-1/PlGF ratio. We compared findings between cases with early-onset FGR only (n = 37) and those that additionally developed PE (n = 36).

RESULTS

Overall perinatal survival was 63/73 (86.3%). A sFlt-1/PlGF ratio above 38 was observed 4 weeks before delivery in most FGR-only and FGR with PE cases (73% and 100%, respectively), but absolute values of sFlt-1/PlGF were significantly higher in FGR cases with PE. Extremely elevated values of the ratio (≥ 655) within the last 48 h before delivery were found in 65% of cases of FGR with PE, but in only 8% of isolated FGR cases (P < 0.001).

CONCLUSION

Elevated sFlt-1/PlGF was observed in most early-onset FGR pregnancies from 4 weeks before delivery, and values were even higher if there was concurrent PE. However, serial measurements of the ratio were of limited value, being useful only to anticipate the need for imminent delivery in cases of FGR with PE when sFlt-1/PlGF values ≥ 655 were reached. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Preoperative administration of eculizumab to prevent surgery-triggered hemolysis during cesarean section with paroxysmal nocturnal hemoglobinuria

Eculizumab in pregnancy has been reported to be effective in improving outcomes in patients with paroxysmal nocturnal hemoglobinuria. However, a cesarean section may result in surgery-triggered hemolysis. An additional dose of eculizumab just prior to delivery is an appropriate choice to prevent postoperative hemolysis.

Assessing the sensitivity of placental growth factor and soluble fms-like tyrosine kinase 1 at 36 weeks' gestation to predict small-for-gestational-age infants or late-onset preeclampsia: a prospective nested case-control study

Background

Fetal growth restriction is a disorder of placental dysfunction with three to four-fold increased risk of stillbirth. Fetal growth restriction has pathophysiological features in common with preeclampsia. We hypothesised that angiogenesis-related factors in maternal plasma, known to predict preeclampsia, may also detect fetal growth restriction at 36 weeks’ gestation. We therefore set out to determine the diagnostic performance of soluble fms-like tyrosine kinase 1 (sFlt-1), placental growth factor (PlGF), and the sFlt-1:PlGF ratio, measured at 36 weeks’ gestation, in identifying women who subsequently give birth to small-for-gestational-age (SGA; birthweight <10th centile) infants. We also aimed to validate the predictive performance of the analytes for late-onset preeclampsia in a large independent, prospective cohort.

Methods

A nested 1:2 case-control study was performed including 102 cases of SGA infants and a matched group of 207 controls; and 39 cases of preeclampsia. We determined the diagnostic performance of each angiogenesis-related factor, and of their ratio, to detect SGA infants or preeclampsia, for a predetermined 10% false positive rate.

Results

Median plasma levels of PlGF at 36 weeks’ gestation were significantly lower in women who subsequently had SGA newborns (178.5 pg/ml) compared to normal birthweight controls (326.7 pg/ml, p < 0.0001). sFlt-1 was also higher among SGA cases, but this was not significant after women with concurrent preeclampsia were excluded. The sensitivity of PlGF to predict SGA infants was 28.8% for a 10% false positive rate. The sFlt-1:PlGF ratio demonstrated better sensitivity for preeclampsia than either analyte alone, detecting 69.2% of cases for a 10% false positive rate.

Conclusions

Plasma PlGF at 36 weeks’ gestation is significantly lower in women who subsequently deliver a SGA infant. While the sensitivity and specificity of PlGF currently limit clinical translation, our findings support a blood-based biomarker approach to detect late-onset fetal growth restriction. Thirty-six week sFlt-1:PlGF ratio predicts 69.2% of preeclampsia cases, and could be a useful screening test to triage antenatal surveillance.

Electronic supplementary material

The online version of this article (10.1186/s12884-018-1992-x) contains supplementary material, which is available to authorized users.

Maternal demographic factors associated with emergency caesarean section for non-reassuring foetal status

OBJECTIVES

This study aimed to determine maternal and obstetric factors associated with emergency caesarean section (CS) for non-reassuring foetal status (NRFS).

MATERIALS AND METHODS

This was a retrospective analysis of term singleton births between January 2007 and December 2015 at the Mater Mother's Hospital in Brisbane. The study group comprised all cases of emergency CS for NRFS, and the control cohort comprised all other births meeting the inclusion criteria but excluding those in the study cohort.

RESULTS

Over the study period, there were 74,177 births fulfilling the inclusion criteria. The overall rate of emergency CS for NRFS was 4.2% (3132/74,177). Multivariate analysis showed that being overweight and obese, Indian and "other" ethnicity, artificial reproductive techniques, smoking, induction of labour and gestation at 39-42 weeks were associated with an increased risk, whereas being underweight, female sex, hypertension and birth without labour conferred a lower risk.

CONCLUSION

Many maternal and obstetric factors were associated with emergency CS for NRFS and influenced adverse perinatal outcomes. Recognition of these risk factors could help risk stratify women prior to labour.

sFlt-1/PlGF and Doppler ultrasound parameters in SGA pregnancies with confirmed neonatal birth weight below 10th percentile

We explored whether there was a relationship between the sFlt-1/PlGF ratio in early-late and late-onset SGA patients and whether it is associated with neonatal birth weight.

MATERIAL/METHODS

110 patients who were diagnosed with a fetal weight below the 10th percentile for gestational age and who at the same time delivered neonates with a birth weight below the 10th percentile for gestational age. For each of the patients sFlt-1, PlGF and the sFlt-1/PlGF ratio were studied and uterine artery (UtA) and umbilical artery (UA) Doppler were performed.

RESULTS

sFlt-1/PlGF ratios and neonatal birth weight which showed significant negative correlation across the entire population studied (R = -0.46, p < 0.001). In late-onset SGA patients this negative correlation was observed, as well (R = -0.54, p < 0.001) In the group of patients with pregnancies older than 34 weeks and an sFlt-1/PlGF ratio ≥38, we observed a significantly lower neonatal birth weight when compared to the same gestational age group with an sFlt-1/PlGF ratio <38 (2045 g vs 2405 g, p < 0.001).

CONCLUSION

Late-onset SGA syndromes are characterized by lower sFlt-1/PlGF ratios, which indicates a lower degree of placental function impairment. The sFlt-1/PlGF ratio can be a predictor of more significant growth disorders and a lower neonatal birth weight. The sFlt-1/PlGF ratio can be helpful in distinguishing between disordered angiogenesis-dependent and other causes of late-onset SGA cases.

Predicting intrapartum fetal compromise at term using the cerebroplacental ratio and placental growth factor levels (PROMISE) study: randomised controlled trial protocol

INTRODUCTION

Intrapartum complications are a major contributor to adverse perinatal outcomes, including stillbirth, hypoxic-ischaemic brain injury and subsequent longer term disability. In many cases, hypoxia develops as a gradual process due to the inability of the fetus to tolerate the stress of parturition suggesting reduced fetoplacental reserve before labour commences. The fetal cerebroplacental ratio (CPR) is an independent predictor of intrapartum fetal compromise, poor acid base status at birth and of neonatal unit admission at term. Similarly, circulating maternal levels of placental growth factor (PlGF) are lower in pregnancies complicated by placental dysfunction. This paper outlines the protocol for the PROMISE Study, which aims to determine if the introduction of a prelabour screening test for intrapartum fetal compromise combining the CPR and maternal PlGF level results in a reduction of adverse perinatal outcomes.

METHODS AND ANALYSIS

This is a single-site, non-blinded, individual patient randomised controlled trial of a screening test performed at term, combining the fetal CPR and maternal serum PlGF. Women with a singleton, non-anomalous pregnancy will be recruited after 34 weeks' gestation and randomised to either receive the screening test or not. Screened pregnancies determined to be at risk will be recommended induction of labour. Demographic, obstetric history and antenatal data will be collected at enrolment, and perinatal outcomes will be recorded after delivery. Relative risks and 95% CIs will be reported for the primary outcome. Regression techniques will be used to examine the influence of prognostic factors on the primary and secondary outcomes.

ETHICS AND DISSEMINATION

This study has been reviewed and approved by the Mater Human Research Ethics Committee (Reference: HREC EC00332) and will follow the principles of Good Clinical Practice. The study results will be disseminated at national and international conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ACTRN12616001009404; Pre-results.

Adverse pregnancy outcomes and imbalance in angiogenic growth mediators and oxidative stress biomarkers is associated with advanced maternal age births: A prospective cohort study in Ghana

Background

Advanced maternal age (AMA) has been associated with negative pregnancy outcomes. Oxidative stress (OS) and defective placental dysfunction are contributing factors. This study determined the association between AMA and adverse pregnancy outcomes, OS biomarkers and angiogenic growth mediators (AGMs) in normal pregnancies.

Methods

This prospective cohort study conducted at the Obstetrics and Gynaecology (O&G) Department of the Komfo Anokye Teaching Hospital (KATH) finally included 175 normal pregnant women comprising, 58 AMA (35–45 years), 55 (30–34 years) and 62 optimal childbearing age (20–29 years). Venous blood samples were collected at 28–32 weeks for soluble fms-like tyrosine kinase-1 (sFlt-1), placental growth factor (PIGF), 8-epiprostaglandinF2-α (8-epi-PGF2α) and total antioxidant capacity (TAC) assays.

Results

Pregnancies of AMA had a significantly higher levels of sFlt-1, 8-epi-PGF2α and 8-epi-PGF2α: PIGF ratio but a reduced level of PIGF, TAC and PIGF: sFlt-1 ratio compared to 20–29 years (p<0.0001). A significant negative correlation between AMA and PIGF (r = -0.294; p = 0.038); TAC (r = -0.215; p = 0.001) and PIGF: sFlt-1 ratio (r = -0.457; p<0.0001) and a positive correlation with sFlt-1 (r = 0.269; p = 0.017), 8-epiPGF2α (r = 0.277; p = 0.029) and 8-epi-PGF2: PIGF ratio (r = 0.461; p<0.0001) levels were observed. The adjusted odds ratio (aOR), and 95% confidence interval, and p value for the significant independent adverse outcomes associated with AMA were emergency caesarean section [21.7 (5.9–121.3), p<00001], elective caesarean section [2.7(0.9–5.8), p = 0.0105], stillbirth [12.6(1.4–82.1), p<0.0001], post-partum haemorrhage [4.3(1.1–18.5), p = 0.0094], preterm delivery [8.2(3.5–28.4), p<0.0001], low birth weight babies [9.7(2.8–29.3), p<0.0001], birth asphyxia [3.8(1.6–12.7), p = 0.0054], Apgar score ≤ 7 after 5 min for babies [10.1(4.7–23.2), p<0.0001], placental abruption [3.5(1.3–8.4), p = 0.0117] and intrauterine growth restriction (IUGR) [4.6(2.3–12.9), p = 0.0001].

Conclusion

AMA pregnancies correlate with adverse pregnancy outcomes and imbalance in OS biomarkers and AGMs. It is incumbent on health care givers to provide effective antenatal care among AMA mothers as early identification of these imbalance and treatment can prevent adverse pregnancy outcomes.

Clinical implementation of the sFlt-1/PlGF ratio to identify preeclampsia and fetal growth restriction: A prospective cohort study

OBJECTIVE

To analyze the usefulness of a clinical protocol for early detection of preeclampsia and/or fetal growth restriction (PE/FGR) using, in previously selected pregnancies, the measurement of the sFlt-1/PlGF ratio at 24-28 weeks of gestation.

STUDY DESIGN

Prospective observational cohort study carried out in a single tertiary hospital in Spain. 5601 consecutive singleton pregnancies with complete follow-up were included. High-risk women for PE/FGR were selected by combining data from maternal history and second trimester uterine artery Doppler. Subsequently these patients underwent intensive monitoring, including the measurement of the sFlt-1/PlGF ratio at 24-28 weeks to predict PE/FGR.

MAIN OUTCOME MEASURES

Early, intermediate and late PE/FGR (delivery <32 + 0, 32 + 0 - <36 + 0 and ≥36 + 0 weeks, respectively).

RESULTS

Overall incidence of early, intermediate and late PE/FGR was 0.3%, 0.7% and 3.2%, respectively, being higher in the 4.3% of women selected for intensive monitoring: 5.8%, 8.7% and 15.4%, respectively (all p < 0.001). The area under the curve (AUC) with 95%CI of the sFlt-1/PlGF ratio for detecting early PE/FGR was 0.98 (0.97-1.00), and the sFlt-1/PlGF ratio >95th centile showed a sensitivity (%) of 100 (95%CI, 78.5-100) and specificity (%) of 80.6 (95%CI, 75.0-85.2). The AUC of the sFlt-1/PlGF ratio for detecting intermediate and late PE/FGR was of 0.87 (95%CI, 0.77-0.97) and 0.68 (95%CI, 0.58-0.79), respectively.

CONCLUSION

A contingent strategy of measuring the sFlt-1/PlGF ratio at 24-28 weeks in women previously selected by clinical factors and uterine artery Doppler enables an accurate prediction of PE/FGR. This performance is optimal to predict PE/FGR requiring delivery before 32 weeks.

Infant size and the association between maternal circulating angiogenic factors and preeclampsia

OBJECTIVE

To assess the effect of infant size as a marker of placental function on the association between preeclampsia and the ratio of soluble fms-like tyrosine kinase 1 (sFlt-1) to placental growth factor (PlGF).

STUDY DESIGN

The angiogenic factors sFlt-1 and PlGF were measured prospectively at 26 weeks gestation in 2322 women. Pregnancies were stratified by whether or not they were complicated by preeclampsia, the timing of delivery, and birthweight Z-score.

RESULT

Independent of preeclampsia status, women with small infants (Z < -1.0) have an increased sFlt-1/PlGF ratio, and women with large infants (Z > 1.0) have a decreased ratio. Among pregnancies yielding small infants, the sFlt-1/PlGF ratio is markedly elevated in preeclamptic pregnancies requiring delivery before 37 weeks (110.0 vs. 17.9, p < 0.0001) but not in preeclamptic pregnancies delivered at term. The strength of the association between preeclampsia and the sFlt-1/PlGF ratio is increased for small infants compared to normal-sized or large infants.

CONCLUSION

The sFlt-1/PlGF ratio in the late second trimester is similarly elevated in women with preeclampsia and in women with small infant size and more markedly elevated in a syndrome of placental dysfunction characterized by preeclampsia, preterm delivery, and growth restriction.

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

OBJECTIVES

The aim of this study was to investigate, whether maternal serum levels of sFlt-1, PlGF and PAPP-A at third trimester of pregnancy are associated with late-onset PE and intrauterine growth retardation (IUGR) after 34 weeks of pregnancy.

METHODS

This was a prospective study measuring the maternal serum levels of soluble tyrosine kinase-1 (sFlt-1), placental growth factor (PlGF) and pregnancy-associated plasma protein-A (PAPP-A) at 32-37 weeks of pregnancy: 730 patients were enrolled and 676 had neither intrauterine growth restriction (IUGR) nor preeclampsia (PE) or pregnancy induced hypertension (PIH) throughout the pregnancy. 22 patients developed IUGR, 32 PE and 24 PIH.

RESULTS

Linear regression analyses after adjusting for maternal age, gestational age at the blood sampling and maternal BMI showed associations between PE and serum sFlt-1 levels (Exp(ß) = 3.29; 95% CI: 2.69-4.04), serum PlGF levels (Exp(ß) = 0.18; 95% CI: 0.13-0.24), sFlt-1/PlGF ratio (Exp(ß) = 15.59; 95% CI: 10.64-22.84) and serum PAPP-A (Exp(ß) = 1.48; 95% CI 1.15-1.89). sFlt-1, PlGF and sFlt-1/PlGF-Ratio showed comparable area under the curve (AUC) estimates with a predictive ability to discriminate pregnancies developing PE and IUGR from controls. The predictive ability of PAPP-A for PE was only slightly better than chance.

CONCLUSIONS

This study supported the ability of a single measurement of sFlt-1/PlGF ratio at third trimester to predict PE and IUGR occurring after 34 weeks of pregnancy. However, larger multicentre studies are needed to replicate our results.

Systematic review of maternal Placental Growth Factor levels in late pregnancy as a predictor of adverse intrapartum and perinatal outcomes

AIM

This systematic review evaluates the utility of maternal Placental Growth Factor (PlGF) when measured in late pregnancy (>20 weeks) as a predictor of adverse obstetric and perinatal outcomes.

METHODS

Pubmed and Embase were searched using the term "placental growth factor" in combination with relevant perinatal outcomes. Studies were included if they measured PlGF levels in pregnant women after 20 + 0 weeks gestation and reported relevant adverse obstetric or perinatal outcomes related to placental insufficiency (excluding pre-eclampsia).

RESULTS

Twenty-six studies were eligible for inclusion with 21 studies investigating the relationship between PlGF and small for gestational age (SGA) and 7 studies investigating PlGF for the prediction of other adverse perinatal outcomes. In all studies, maternal PlGF levels were significantly lower in the SGA group compared to controls. Other outcomes investigated included caesarean section (CS) for fetal compromise, low Apgar score, neonatal intensive care unit (NICU) admission, neonatal acidosis, stillbirth, and intrapartum fetal compromise. The results generally showed a significant association between low PlGF levels and CS for fetal compromise, NICU admission and stillbirth.

CONCLUSION

Low maternal PlGF levels in late pregnancy are strongly associated with SGA. Findings across studies were variable in relation to PlGF and the prediction of other adverse intrapartum and perinatal outcomes, however there was a consistent association between low PlGF levels and CS for fetal compromise, NICU admission and stillbirth. This review suggests that the use of PlGF for the prediction of adverse outcomes is promising. Its predictive value may potentially be enhanced if used in combination with other biomarkers or biophysical measures of fetal well-being.