Screening for pre-eclampsia with competing-risks model using placental growth factor measurement in blood samples collected before 11 weeks' gestation

OBJECTIVES

To describe the distributional properties and assess the performance of placental growth factor (PlGF) measured in blood samples collected before 11 weeks' gestation in the prediction of pre-eclampsia (PE).

METHODS

The study population consisted of pregnant women included in the Pre-eclampsia Screening in Denmark (PRESIDE) study with a PlGF measurement from the routine combined first-trimester screening (cFTS) blood sample collected at 8-14 weeks' gestation. PRESIDE was a prospective multicenter study investigating the predictive performance of the Fetal Medicine Foundation (FMF) first-trimester screening algorithm for PE in a Danish population. In the current study, serum concentration of PlGF in the cFTS blood samples was analyzed in batches between January and June 2021.

RESULTS

A total of 8386 pregnant women were included. The incidence of PE was 0.7% at < 37 weeks' gestation and 3.0% at ≥ 37 weeks. In blood samples collected at 10 weeks' gestation, PlGF multiples of the median (MoM) were significantly lower in pregnancies with preterm PE < 37 weeks compared to unaffected pregnancies. However, PlGF MoM did not differ significantly between pregnancies with PE and unaffected pregnancies in samples collected before 10 weeks' gestation.

CONCLUSIONS

The gestational-age range for PlGF sampling may be expanded from 11-14 to 10-14 weeks when assessing the risk for PE using the FMF first-trimester screening model. There is little evidence to support the use of PlGF in blood samples collected before 10 weeks' gestation. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Reducing the Risk of Preterm Preeclampsia: Comparison of Two First Trimester Screening and Treatment Strategies in a Single Centre in Switzerland

Introduction First trimester screening for preeclampsia (PE) is based on the combined risks model. Recent trials demonstrate that variations in multiple of the medians (MoMs) of the screening markers influence the performance of the algorithm in different populations. The aim of this study is to compare the performance of the algorithm in two cohorts with different prevention strategies.

Material and Methods All first trimester screening tests performed between January 2014 and April 2020 were included. Up to June 2017 pregnancies with a risk > 1 : 200 for early-onset PE (eoPE) were considered at risk and received 100 mg of aspirin (strategy A). From July 2017 onwards, pregnancies with a risk > 1 : 100 for preterm PE (pPE) received 150 mg of aspirin (strategy B). We compared the screen positive rates (SPR) and incidence of PE between the two screening approaches. Statistical analysis were performed with Graphpad 8.0.

Results 3552 pregnancies were included; 1577 pregnancies were screened according to strategy A, 1975 pregnancies according to strategy B. The screen positive rate (SPR) for strategy A and B was 8.9 and 16.9% respectively (p < 0.0001) while the incidence of PE was 1.41 and 1.84% respectively (p = ns).

Conclusion With a SPR of less than 10% we achieved a remarkably low rate of PE in our population, no further reduction in PE could be achieved by an increase in the SPR and LDA-prescription during the second screening period. The cut-off to define a pregnancy at risk for PE should be tailored to keep the SPR below 10% to avoid unnecessary treatment with aspirin.

Prediction of pre-eclampsia

Pre-eclampsia is a leading cause of neonatal and maternal mortality and morbidity that complicates approximately 2-8% of all pregnancies worldwide. The precise cause of pre-eclampsia is not completely understood, with several environmental, genetic, and maternal factors involved in its pathogenesis and pathophysiology. An accurate predictor of pre-eclampsia will facilitate early recognition, close surveillance according to the individual risk and early intervention, and reduce the negative consequences of the disorder. Current evidence shows that no single test predicts pre-eclampsia with sufficient accuracy to be clinically useful. A combination of markers into multiparametric models may provide a more useful and feasible predictive tool for pre-eclampsia screening in the routine care setting than a test of either component alone. This review presents a summary of the current advances on prediction of pre-eclampsia, highlighting their performance and applicability. Key priorities when conducting research on predicting pre-eclampsia are also analyzed.

Evaluation of oxidative/nitrative stress and uterine artery pulsatility index in early pregnancy

Introduction

Increased oxidative/nitrative stress is characteristic not only in pathologic, but also in healthy pregnancy. High uterine artery pulsatility index (UtAPI) at the end of the first trimester is associated with altered placentation and elevated risk for adverse pregnancy outcomes. We aimed to examine the relationship of systemic oxidative/nitrative stress and uterine artery pulsatility index in the first trimester and their correlation to pregnancy outcomes.

Material and methods

Healthy pregnant women were recruited at 12-13th gestational week ultrasound examination; UtAPI was determined by color Doppler ultrasound. Patients were divided into high (UtAPI ≥ 2.3) (n = 30) and low (n = 31) resistance groups, and pregnancies were followed until labor. Systemic oxidative/nitrative stress was estimated by measuring total peroxide level, total antioxidant capacity and nitrotyrosine level.

Results

Plasma total peroxide level was significantly lower (2,510 ± 39 µM vs. 2,285 ± 59 µM), total antioxidant capacity was higher (781 ± 16 mM CRE vs. 822 ± 13 mM CRE) in the high UtAPI group, which were accompanied by lower birth weight (3,317 ± 64 vs. 3,517 ± 77 g, P < 0.05). Plasma total peroxide level showed a negative correlation (by Pearson) to UtAPI (P < 0.01) and positive correlation to birth weight (P < 0.05).

Conclusions

According to our results, lower systemic oxidative stress showed correlation with high UtAPI measured between the 12-13th weeks of gestation. We also found significant differences in the birth weight of healthy newborns; therefore it is worth examining this relationship in pathological pregnancies.

Diagnostic accuracy of first-trimester combined screening for early-onset and preterm pre-eclampsia at 8-10 compared with 11-13 weeks' gestation

OBJECTIVES

To compare the ability of first-trimester combined screening for pre-eclampsia (PE) to predict early-onset and preterm PE when pregnancy-associated plasma protein-A (PAPP-A) and placental growth factor (PlGF) were assessed before vs after 11 weeks' gestation.

METHODS

This was a secondary analysis of a prospective cohort study of singleton pregnancies undergoing routine first-trimester screening conducted at Vall d'Hebron University Hospital, Barcelona, Spain, between October 2015 and September 2017. Demographic characteristics, obstetric history, maternal history and biophysical markers (mean uterine artery pulsatility index and mean arterial blood pressure (MAP)) were recorded at the first-trimester scan (at 11 + 0 to 13 + 6 weeks' gestation). Maternal serum concentrations of PAPP-A and PlGF were assessed from the routine first-trimester blood test (at 8 + 0 to 13 + 6 weeks). Women were classified into two groups depending on whether serum biomarkers were assessed at 8 + 0 to 10 + 6 weeks or at 11 + 0 to 13 + 6 weeks. Probability scores for early-onset and preterm PE were calculated by using two different algorithms: the multivariate Gaussian-distribution model and The Fetal Medicine Foundation (FMF) competing-risks model. Receiver-operating-characteristics (ROC) curves were produced and detection rates at fixed 5% and 10% false-positive rates were computed to compare the performance of these algorithms when PAPP-A and PlGF were assessed before vs after 11 weeks.

RESULTS

Of the 2641 women included, serum biomarkers were assessed before 11 weeks in 1675 (63.4%) and at or after 11 weeks in 966 (36.6%). Of these, 90 (3.4%) women developed PE, including 11 (0.4%) cases of early-onset PE and 30 (1.1%) of preterm PE. Five (45.5%) cases of early-onset and 16 (53.3%) of preterm PE were identified in the group in which serum biomarkers were assessed at 8 + 0 to 10 + 6 weeks and six (54.5%) cases of early-onset and 14 (46.7%) of preterm PE in the group in which serum biomarkers were assessed at 11 + 0 to 13 + 6 weeks. In the prediction of early-onset and preterm PE using the Gaussian algorithm, no differences were observed between the areas under the ROC curves (AUCs) when PAPP-A and PlGF were measured before or after 11 weeks. In the prediction of early-onset and preterm PE using the FMF algorithm, no differences were observed between AUCs for any of the combinations used for risk calculation when the serum biomarkers were obtained before vs after 11 weeks, except for the combination of PAPP-A and MAP, which showed a greater AUC for the prediction of early-onset PE when PAPP-A was measured at or after 11 weeks.

CONCLUSIONS

The prediction of early-onset and preterm PE is similar when serum biomarkers are measured before or after 11 weeks. This allows the use of a two-step approach for PE risk assessment that permits immediate risk calculation at the time of the first-trimester scan. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

A new model for screening for early-onset preeclampsia

BACKGROUND

Early identification of women with an increased risk for preeclampsia is of utmost importance to minimize adverse perinatal events. Models developed until now (mainly multiparametric algorithms) are thought to be overfitted to the derivation population, which may affect their reliability when applied to other populations. Options allowing adaptation to a variety of populations are needed.

OBJECTIVE

The objective of the study was to assess the performance of a first-trimester multivariate Gaussian distribution model including maternal characteristics and biophysical/biochemical parameters for screening of early-onset preeclampsia (delivery <34 weeks of gestation) in a routine care low-risk setting.

STUDY DESIGN

Early-onset preeclampsia screening was undertaken in a prospective cohort of singleton pregnancies undergoing routine first-trimester screening (8 weeks 0/7 days to 13 weeks 6/7 days of gestation), mainly using a 2-step scheme, at 2 hospitals from March 2014 to September 2017. A multivariate Gaussian distribution model including maternal characteristics (a priori risk), serum pregnancy-associated plasma protein-A and placental growth factor assessed at 8 weeks 0/7 days to 13 weeks 6/7 days and mean arterial pressure and uterine artery pulsatility index measured at 11.0-13.6 weeks was used.

RESULTS

A total of 7908 pregnancies underwent examination, of which 6893 were included in the analysis. Incidence of global preeclampsia was 2.3% (n = 161), while of early-onset preeclampsia was 0.2% (n = 17). The combination of maternal characteristics, biophysical parameters, and placental growth factor showed the best detection rate, which was 59% for a 5% false-positive rate and 94% for a 10% false-positive rate (area under the curve, 0.96, 95% confidence interval, 0.94-0.98). The addition of placental growth factor to biophysical markers significantly improved the detection rate from 59% to 94%.

CONCLUSION

The multivariate Gaussian distribution model including maternal factors, early placental growth factor determination (at 8 weeks 0/7 days to 13 weeks 6/7 days), and biophysical variables (mean arterial pressure and uterine artery pulsatility index) at 11 weeks 0/7 days to 13 weeks 6/7 days is a feasible tool for early-onset preeclampsia screening in the routine care setting. Performance of this model should be compared with predicting models based on regression analysis.

Changes in pregnancy-related serum biomarkers early in gestation are associated with later development of preeclampsia

Background

Placental protein expression plays a crucial role during pregnancy. We hypothesized that: (1) circulating levels of pregnancy-associated, placenta-related proteins throughout gestation reflect the temporal progression of the uncomplicated, full-term pregnancy, and can effectively estimate gestational ages (GAs); and (2) preeclampsia (PE) is associated with disruptions in these protein levels early in gestation; and can identify impending PE. We also compared gestational profiles of proteins in the human and mouse, using pregnant heme oxygenase-1 (HO-1) heterozygote (Het) mice, a mouse model reflecting PE-like symptoms.

Methods

Serum levels of placenta-related proteins–leptin (LEP), chorionic somatomammotropin hormone like 1 (CSHL1), elabela (ELA), activin A, soluble fms-like tyrosine kinase 1 (sFlt-1), and placental growth factor (PlGF)–were quantified by ELISA in blood serially collected throughout human pregnancies (20 normal subjects with 66 samples, and 20 subjects who developed PE with 61 samples). Multivariate analysis was performed to estimate the GA in normal pregnancy. Mean-squared errors of GA estimations were used to identify impending PE. The human protein profiles were then compared with those in the pregnant HO-1 Het mice.

Results

An elastic net-based gestational dating model was developed (R² = 0.76) and validated (R² = 0.61) using serum levels of the 6 proteins measured at various GAs from women with normal uncomplicated pregnancies. In women who developed PE, the model was not (R² = -0.17) associated with GA. Deviations from the model estimations were observed in women who developed PE (P = 0.01). The model developed with 5 proteins (ELA excluded) performed similarly from sera from normal human (R² = 0.68) and WT mouse (R² = 0.85) pregnancies. Disruptions of this model were observed in both human PE-associated (R² = 0.27) and mouse HO-1 Het (R² = 0.30) pregnancies. LEP outperformed sFlt-1 and PlGF in differentiating impending PE at early human and late mouse GAs.

Conclusions

Serum placenta-related protein profiles are temporally regulated throughout normal pregnancies and significantly disrupted in women who develop PE. LEP changes earlier than the well-established biomarkers (sFlt-1 and PlGF). There may be evidence of a causative action of HO-1 deficiency in LEP upregulation in a PE-like murine model.

FIRST TRIMESTER SCREENING FOR PREECLAMPSIA - A SYSTEMATIC REVIEW

Objective: To increase the detection rate of preterm preeclampsia (PE) first trimester combined screening tests are being developed. The aim of this review is to create an overview of the currently investigated screening markers, algorithms and their validations.Methods: Comprehensive review of the literature concerning first trimester screening for PEResults and conclusions: Studies investigating a total of 160 biochemical, 6 biophysical and 14 ultrasound markers could be identified. Of the 21 algorithms published, mainly the algorithm published by the Fetal Medicine Foundation London has been validated. This algorithm performes significantly better than screening by anamnestic risk factors only.

First-Trimester Placental Growth Factor for the Prediction of Preeclampsia in Nulliparous Women: The Great Obstetrical Syndromes Cohort Study

BACKGROUND

First-trimester maternal serum markers have been associated with preeclampsia (PE). We aimed to evaluate the performance of first-trimester placental growth factor (PlGF) for the prediction of PE in nulliparous women.

SUBJECTS AND METHODS

We conducted a prospective cohort study of nulliparous women with singleton pregnancy at 11-13 weeks. Maternal serum PlGF concentration was measured using B·R·A·H·M·S PlGFplus KRYPTOR automated assays and reported in multiple of the median adjusted for gestational age. We used proportional hazard models, along with receiver operating characteristic curves and areas under the curve (AUC).

RESULTS

Out of 4,652 participants, we observed 232 (4.9%) cases of PE including 202 (4.3%) term and 30 (0.6%) preterm PE. PlGF was associated with the risk of term (AUC = 0.61, 95% confidence interval [CI] 0.57-0.65) and preterm PE (AUC = 0.73, 95% CI 0.64-0.83). The models were improved with the addition of maternal characteristics (AUC for term PE 0.66, 95% CI 0.62-0.71; AUC for preterm PE 0.81, 95% CI 0.72-0.91; p < 0.01). At a false-positive rate of 10%, PlGF combined with maternal characteristics could have predicted 26% of term and 55% of preterm PE. The addition of pregnancy-associated plasma protein A did not significantly improve the prediction models.

CONCLUSION

First-trimester PlGF combined with maternal characteristics is useful to predict preterm PE in nulliparous women.

High first-trimester maternal blood cystatin C levels despite normal serum creatinine predict pre-eclampsia in singleton pregnancies

Early biochemical identification of women at high risk for the development of pre-eclampsia (PE) is still unsatisfactory. Renal markers measured during the first trimester were analysed to predict later occurrence of PE. A nested case-control study was conducted within the prospective predictive markers for the diagnosis of preeclampsia study. Pregnant women were included at the end of the first trimester and followed up until birth. Controls were matched to PE cases. Renal markers [i.e. creatinine, cystatin C (CysC), β₂ microglobulin (B2M), β-trace protein (BTP), glomerular filtration rate estimations (eGFR) of the aforementioned markers, uric acid (UA), urea, and serum uromodulin (sUMOD)] were compared to placental growth factor (PlGF), a marker known to predict PE later in pregnancy. Reference intervals were determined for the different markers. In the 183 women (PE, n = 39; controls, n = 144), CysC, the CysC/PlGF ratio (p < .01) and UA were higher, whereas the eGFR_CysC/eGFR_Crea ratio (a marker of glomerular endothelial integrity and shrunken pore syndrome) and PlGF were lower in women who developed PE (p < .05 for all). Compromised filtration of the larger molecule CysC together with a normal creatinine, in a subset of PE cases (15.3%) was a unique, strong and independent predictor of later PE if the baseline CysC concentration was >0.85 mg/l. In conclusion, CysC and its derivatives as well as UA, indicating volume expansion, measured at the end of the first trimester are predictive of PE. Thus, women can be easily identified and followed as an early reduction in glomerular filtration quality poses a high risk for a subsequent development of PE.