Fetal cerebral blood-flow redistribution: analysis of Doppler reference charts and association of different thresholds with adverse perinatal outcome

Reproducibility of fetal ultrasound doppler parameters used for growth assessment

OBJECTIVES

To produce standards of references for quality control and assess the reproducibility of fetal ultrasound Doppler measurements commonly used for blood flow assessment in fetal growth.

METHODS

Women with singleton normal pregnancies were prospectively recruited at University College London Hospital, UK, between 24 and 41 weeks. Umbilical artery (UA), middle cerebral artery (MCA), and their pulsatility indices (PI), resistance indices (RI) and ratios such as cerebro-placental (CPR) and umbilical cerebral ratio (UCR) were obtained twice by two sonographers in training or after completion of training, blind to each other's measurements. Bland-Altman plots were generated, the mean differences and 95% limits of agreement (LOA) were calculated to assess intra- and interobserver reproducibility. Values were expressed as absolute values or as z-score.

RESULTS

One hundred ten women were recruited. Overall reproducibility was variable for absolute values and highly variable for z-scores, independently from vessel sampled, index or ratio used, intra- or interobserver reproducibility. The widest absolute values of 95% LOA were 0.3 for UA PI, 0.7 for MCA PI, 0.9 for CPR and 0.3 for UCR, respectively. Regarding z-score, the widest 95% LOA were 1.9 for UA PI, 2.1 for CPR and 1 for UCR. Reproducibility was slightly better for intra- compared with interobserver variability. There was significant difference in z-score reproducibility between MCA peak systolic velocity and CPR vs UCR.

CONCLUSIONS

Reference standards of reproducibility of fetal Doppler parameters are produced for standardization and quality-control purposes. Overall, the reproducibility for fetal Doppler parameters was variable independently from vessel sampled, Doppler index (PI or RI) or ratio used, intra- and interobserver comparison. UCR was the most reproducible parameter which should be recommended, together with UA PI, for clinical use and in research studies on fetal growth.

Diagnostic value of combined maternal cardiac work and fetoplacental circulation parameters in detecting fetal intrauterine hypoxia in preeclamptic women

To investigate the correlation between fetoplacental circulation and maternal left ventricular myocardial work (MW) parameters in patients with preeclampsia (PE) and the prediction of fetal hypoxia. Seventy-eight PE patients (PE group) were assigned to intrauterine-hypoxia (27) and non-intrauterine-hypoxia (51) groups, and 45 healthy pregnant women were controls. The receiver operating characteristic (ROC) curve evaluated the diagnostic efficacy of each parameter for fetal intrauterine hypoxia. Relative to the controls and the non-intrauterine-hypoxia group, the umbilical artery (UA) S/D, PI, and RI, as well as the global work index (GWI), global effective work, and global ineffective work, increased in the PE group and intrauterine-hypoxia group (P < 0.05), respectively, while the cerebroplacental ratio (CPR) and global work efficiency decreased (P < 0.05). Relative to the controls group, the middle cerebral artery S/D, PI, and RI decreased in the PE group (P < 0.05). Correlation analysis showed that the fetoplacental circulation parameters were correlated with MW parameters (P < 0.05), and CPR achieved the highest correlation. ROC curves showed that UA-S/D, combined with GWI, produced the highest predictive value for fetal hypoxia in PE patients. There was a linear correlation between MW parameters and fetoplacental parameters, and CPR showed the highest correlation with MW. UA-S/D, combined with GWI, exhibited optimal diagnostic efficacy in predicting fetal intrauterine hypoxia in PE patients.

Using Doppler ultrasound to assess fetal cardiac function and pregnancy outcomes in obstetric antiphospholipid syndrome pregnancies: a case-control study

PURPOSE

This study aimed to evaluate fetal left ventricular function (LVF) in pregnant women with obstetric antiphospholipid syndrome (OAPS) by Doppler ultrasound and developed a clinical nomogram to predict adverse perinatal outcomes.

METHODS

In this prospective observational study, 105 pregnant women were enrolled and divided into the OAPS cohort (n = 60) and the control cohort (n = 45). Fetal cardiac function parameters were collected and compared between two cohorts. Univariate and multivariate analysis was conducted to select the risk factors associated with adverse perinatal outcomes, and a clinical nomogram was developed based on these selected risk factors. The predictive performance of corresponding indicators for adverse perinatal outcomes was evaluated using receiver operating characteristic (ROC) curve analysis.

RESULTS

The OAPS cohort revealed an increase in the isovolumic relaxation time (IVRT) and myocardial performance index (MPI), a decrease in the ejection time (ET), middle cerebral artery pulsatility index (MCA-PI) and cerebroplacental ratio (CPR) compared to the control cohort. Through univariate and multivariate analysis, gravidity, CPR, and MPI were the risk factors associated with adverse perinatal outcomes. A model predicting adverse perinatal outcomes in OAPS pregnant women was constructed based on these three factors and visualized as a nomogram. The nomogram could accurately predict adverse perinatal outcomes with an area under the curve of 0.923 (95% CI: 0.858-0.982). This performance was better than evaluating individual factors such as MPI (0.825, 95% CI: 0.739-0.911) and CPR (0.816, 95% CI: 0.705-0.927) for efficacy.

CONCLUSION

MPI can be used to assess fetal LVF and predict adverse perinatal outcomes. We developed a nomogram to predict adverse perinatal outcomes in OAPS women. This imaging-based evidence can provide timely clinical intervention, enabling personalized clinical decision-making.

Comparison of Cerebral Blood Circulation of Fetuses with Congenital Heart Disease with Healthy Fetuses

Background

The effect of congenital cardiac malformation on fetal cerebral circulation has not been well known. This study aimed to compare the cerebral blood circulation of fetuses with congenital heart disease (CHD) with healthy fetuses.

Methods

This prospective cohort study included 37 pregnant women who presented to the gynecology and obstetrics department of department of Farabi Hospital, Faculty of Medicine, Karadeniz Technical University for anomaly screening in the second trimester. The women were divided into two groups as those with fetuses having CHD and healthy fetuses. Middle cerebral artery (MCA), peak systolic velocity (PSV), pulsatility index (PI), resistivity index (RI), systole/diastole (S/D) ratio, and MCA transverse section diameter (mm) were recorded for each fetus.

Results

The most common CHDs were truncus arteriosus and hypoplastic left heart syndrome. The mean MCA PSV, resistivity index, and MDCA vessel diameter values were statistically significantly higher in the study group compared with fetuses without CHDs. The mean PI and systole/diastole ratio were statistically significantly lower in the study group than in the control group.

Conclusion

This study reported that MCA PSV, RI, and vessel diameter were significantly higher and the S/D ratio and PI were significantly lower in fetuses with CHD compared to the healthy fetuses.

Doppler ultrasound of umbilical and middle cerebral artery in third trimester small-for-gestational age fetuses to decide on timing of delivery for suspected fetal growth restriction: A cohort with nested RCT (DRIGITAT)

OBJECTIVE

To assess the association of the umbilicocerebral ratio (UCR) with adverse perinatal outcome in late preterm small-for-gestational age (SGA) fetuses and to investigate the effect on perinatal outcomes of immediate delivery.

DESIGN

Multicentre cohort study with nested randomised controlled trial (RCT).

SETTING

Nineteen secondary and tertiary care centres.

POPULATION

Singleton SGA pregnancies (estimated fetal weight [EFW] or fetal abdominal circumference [FAC] <10th centile) from 32 to 36+6 weeks.

METHODS

Women were classified: (1) RCT-eligible: abnormal UCR twice consecutive and EFW below the 3rd centile at/or below 35 weeks or below the 10th centile at 36 weeks; (2) abnormal UCR once or intermittent; (3) never abnormal UCR. Consenting RCT-eligible patients were randomised for immediate delivery from 34 weeks or expectant management until 37 weeks.

MAIN OUTCOME MEASURES

A composite adverse perinatal outcome (CAPO), defined as perinatal death, birth asphyxia or major neonatal morbidity.

RESULTS

The cohort consisted of 690 women. The study was halted prematurely for low RCT-inclusion rates (n = 40). In the RCT-eligible group, gestational age at delivery, birthweight and birthweight multiple of the median (MoM) (0.66, 95% confidence interval [CI] 0.59-0.72) were significantly lower and the CAPO (n = 50, 44%, p < 0.05) was more frequent. Among patients randomised for immediate delivery there was a near-significant lower birthweight (p = 0.05) and higher CAPO (p = 0.07). EFW MoM, pre-eclampsia, gestational hypertension and Doppler classification were independently associated with the CAPO (area under the curve 0.71, 95% CI 0.67-0.76).

CONCLUSIONS

Perinatal risk was effectively identified by low EFW MoM and UCR. Early delivery of SGA fetuses with an abnormal UCR at 34-36 weeks should only be performed in the context of clinical trials.

Prenatal prediction of adverse outcome using different charts and definitions of fetal growth restriction

OBJECTIVE

Antenatal growth assessment using ultrasound aims to identify small fetuses that are at higher risk of perinatal morbidity and mortality. This study explored whether the association between suboptimal fetal growth and adverse perinatal outcome varies with different definitions of fetal growth restriction (FGR) and different weight charts/standards.

METHODS

This was a retrospective cohort study of 17 261 singleton non-anomalous pregnancies at ≥ 24 + 0 weeks' gestation that underwent routine ultrasound at a tertiary referral hospital. Estimated fetal weight (EFW) and Doppler indices were converted into percentiles using a reference standard (INTERGROWTH-21st (IG-21)) and various reference charts (Hadlock, Fetal Medicine Foundation (FMF) and Swedish). Test characteristics were assessed using the consensus definition, Society for Maternal-Fetal Medicine (SMFM) definition and Swedish criteria for FGR. Adverse perinatal outcome was defined as perinatal death, admission to the neonatal intensive care unit at term, 5-min Apgar score < 7 and therapeutic cooling for neonatal encephalopathy. The association between FGR according to each definition and adverse perinatal outcome was compared. Multivariate logistic regression analysis was used to test the strength of association between ultrasound parameters and adverse perinatal outcome. Ultrasound parameters were also tested for correlation.

RESULTS

IG-21, Hadlock and FMF fetal size references classified as growth-restricted 1.5%, 3.6% and 4.6% of fetuses, respectively, using the consensus definition and 2.9%, 8.8% and 10.6% of fetuses, respectively, using the SMFM definition. The sensitivity of the definition/chart combinations for adverse perinatal outcome varied from 4.4% (consensus definition with IG-21 charts) to 13.2% (SMFM definition with FMF charts). Specificity varied from 89.4% (SMFM definition with FMF charts) to 98.6% (consensus definition with IG-21 charts). The consensus definition and Swedish criteria showed the highest specificity, positive predictive value and positive likelihood ratio in detecting adverse outcome, irrespective of the reference chart/standard used. Conversely, the SMFM definition had the highest sensitivity across all investigated growth charts. Low EFW, abnormal mean uterine artery pulsatility index (UtA-PI) and abnormal cerebroplacental ratio were significantly associated with adverse perinatal outcome and there was a positive correlation between the covariates. Multivariate logistic regression showed that UtA-PI > 95th percentile and EFW < 5th percentile were the only parameters consistently associated with adverse outcome, irrespective of the definitions or fetal growth chart/standard used.

CONCLUSIONS

The apparent prevalence of FGR varies according to the definition and fetal size reference chart/standard used. Irrespective of the method of classification, the sensitivity for the identification of adverse perinatal outcome remains low. EFW, UtA-PI and fetal Doppler parameters are significant predictors of adverse perinatal outcome. As these indices are correlated with one other, a prediction algorithm is advocated to overcome the limitations of using these parameters in isolation. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Assessment of fetal resistance to hypoxia using the Stange test as an adjunct to Apgar scale assessment of neonatal health status

It has been established that the cause of biological death of fetuses in stillbirths and the cause of neonatal encephalopathies in live births is hypoxic brain cell damage in fetuses. Timely cesarean section remains the most effective way to preserve fetal life and health in the face of lethal intrauterine hypoxia. However, there is no universally recognized methodology for assessing fetal adaptation reserves to hypoxia and no methodology for selecting the type of delivery in order to perform a timely cesarean section if necessary. The Apgar score, which has been used since 1952, allows assessment of neonatal health at 1 and 5 minutes after birth, but this assessment is made without taking into account the health of the fetus before delivery. In recent years, it has been established that the outcome of fetal hypoxia is determined not only by its duration, but also by the amount of adaptive reserves available in the fetus to hypoxia. It was found that the duration of fetal immobility during apnea of a pregnant woman is an indicator of fetal resistance to hypoxia. In 2011, a method of assessing fetal resistance to intrauterine hypoxia based on the Stange test was developed in Russia. It has been found that the maximum duration of fetal immobility during maternal apnea is normally more than 30 seconds, while in the presence of fetal signs of fetoplacental insufficiency it does not reach 30 seconds, and in the presence of signs of severe fetoplacental insufficiency it does not reach 10 seconds. Therefore, it was proposed to consider good fetal resistance to hypoxia as an indication for vaginal delivery, and poor fetal resistance to hypoxia as an indication for cesarean section. A technique for assessing fetal resistance to hypoxia is described that has been developed for independent use by every pregnant woman. It is shown that it is sufficient for her to have a stopwatch and to be able to record the maximum period of fetal immobility during voluntary apnea. It is hoped that a measure of fetal resistance to hypoxia could be a meaningful complement to the Apgar score of neonatal health. It is envisioned that the use of a modified Stange test could help physicians prevent stillbirths and neonatal encephalopathies.

Do differences in diagnostic criteria for late fetal growth restriction matter?

BACKGROUND

Criteria for diagnosis of fetal growth restriction differ widely according to national and international guidelines, and further heterogeneity arises from the use of different biometric and Doppler reference charts, making the diagnosis of fetal growth restriction highly variable.

OBJECTIVE

This study aimed to compare fetal growth restriction definitions between Delphi consensus and Society for Maternal-Fetal Medicine definitions, using different standards/charts for fetal biometry and different reference ranges for Doppler velocimetry parameters.

STUDY DESIGN

From the TRUFFLE 2 feasibility study (856 women with singleton pregnancy at 32+0 to 36+6 weeks of gestation and at risk of fetal growth restriction), we selected 564 women with available mid-pregnancy biometry. For the comparison, we used standards/charts for estimated fetal weight and abdominal circumference from Hadlock, INTERGROWTH-21st, and GROW and Chitty. Percentiles for umbilical artery pulsatility index and its ratios with middle cerebral artery pulsatility index were calculated using Arduini and Ebbing reference charts. Sensitivity and specificity for low birthweight and adverse perinatal outcome were evaluated.

RESULTS

Different combinations of definitions and reference charts identified substantially different proportions of fetuses within our population as having fetal growth restriction, varying from 38% (with Delphi consensus definition, INTERGROWTH-21st biometric standards, and Arduini Doppler reference ranges) to 93% (with Society for Maternal-Fetal Medicine definition and Hadlock biometric standards). None of the different combinations tested appeared effective, with relative risk for birthweight <10th percentile between 1.4 and 2.1. Birthweight <10th percentile was observed most frequently when selection was made with the GROW/Chitty charts, slightly less with the Hadlock standard, and least frequently with the INTERGROWTH-21st standard. Using the Ebbing Doppler reference ranges resulted in a far higher proportion identified as having fetal growth restriction compared with the Arduini Doppler reference ranges, whereas Delphi consensus definition with Ebbing Doppler reference ranges produced similar results to those of the Society for Maternal-Fetal Medicine definition. Application of Delphi consensus definition with Arduini Doppler reference ranges was significantly associated with adverse perinatal outcome, with any biometric standards/charts. The Society for Maternal-Fetal Medicine definition could not accurately detect adverse perinatal outcome irrespective of estimated fetal weight standard/chart used.

CONCLUSION

Different combinations of fetal growth restriction definitions, biometry standards/charts, and Doppler reference ranges identify different proportions of fetuses with fetal growth restriction. The difference in adverse perinatal outcome may be modest, but can have a significant impact in terms of rate of intervention.

Umbilical Vein Blood Flow in Uncomplicated Pregnancies: Systematic Review of Available Reference Charts and Comparison with a New Cohort

The objectives of the study were (1) to perform a systematic review of the available umbilical vein blood flow volume (UV-Q) reference ranges in uncomplicated pregnancies; and (2) to compare the findings of the systematic review with UV-Q values obtained from a local cohort. Available literature in the English language on this topic was identified following the PRISMA guidelines. Selected original articles were further grouped based on the UV sampling sites and the formulae used to compute UV-Q. The 50th percentiles, the means, or the best-fitting curves were derived from the formulae or the reported tables presented by authors. A prospective observational study of uncomplicated singleton pregnancies from 20⁺⁰ to 40⁺⁶ weeks of gestation was conducted to compare UV-Q with the results of this systematic review. Fifteen sets of data (fourteen sets belonging to manuscripts identified by the research strategy and one obtained from our cohort) were compared. Overall, there was a substantial heterogeneity among the reported UV-Q central values, although when using the same sampling methodology and formulae, the values overlap. Our data suggest that when adhering to the same methodology, the UV-Q assessment is accurate and reproducible, thus encouraging further investigation on the possible clinical applications of this measurement in clinical practice.

Developmental Ultrasound Characteristics in Guinea Pigs: Similarities with Human Pregnancy

BACKGROUND

Biometrical and blood flow examinations are fundamental for assessing fetoplacental development during pregnancy. Guinea pigs have been proposed as a good model to study fetal development and related gestational complications; however, longitudinal growth and blood flow changes in utero have not been properly described. This study aimed to describe fetal and placental growth and blood flow of the main intrauterine vascular beds across normal guinea pig pregnancy and to discuss the relevance of this data for human pregnancy.

METHODS

Pregnant guinea pigs were studied from day 25 of pregnancy until term (day ~70) by ultrasound and Doppler assessment. The results were compared to human data from the literature.

RESULTS

Measurements of biparietal diameter (BPD), cranial circumference (CC), abdominal circumference, and placental biometry, as well as pulsatility index determination of umbilical artery, middle cerebral artery (MCA), and cerebroplacental ratio (CPR), were feasible to determine across pregnancy, and they could be adjusted to linear or nonlinear functions. In addition, several of these parameters showed a high correlation coefficient and could be used to assess gestational age in guinea pigs. We further compared these data to ultrasound variables from human pregnancy with high similarities.

CONCLUSIONS

BPD and CC are the most reliable measurements to assess fetal growth in guinea pigs. Furthermore, this is the first report in which the MCA pulsatility index and CPR are described across guinea pig gestation. The guinea pig is a valuable model to assess fetal growth and blood flow distribution, variables that are comparable with human pregnancy.

Reduced fetal growth velocity and weight loss are associated with adverse perinatal outcome in fetuses at risk of growth restriction

BACKGROUND

Although fetal size is associated with adverse perinatal outcome, the relationship between fetal growth velocity and adverse perinatal outcome is unclear.

OBJECTIVE

This study aimed to evaluate the relationship between fetal growth velocity and signs of cerebral blood flow redistribution, and their association with birthweight and adverse perinatal outcome.

STUDY DESIGN

This study was a secondary analysis of the TRUFFLE-2 multicenter observational prospective feasibility study of fetuses at risk of fetal growth restriction between 32⁺⁰ and 36⁺⁶ weeks of gestation (n=856), evaluated by ultrasound biometry and umbilical and middle cerebral artery Doppler. Individual fetal growth velocity was calculated from the difference of birthweight and estimated fetal weight at 3, 2, and 1 week before delivery, and by linear regression of all available estimated fetal weight measurements. Fetal estimated weight and birthweight were expressed as absolute value and as multiple of the median for statistical calculation. The coefficients of the individual linear regression of estimated fetal weight measurements (growth velocity; g/wk) were plotted against the last umbilical-cerebral ratio with subclassification for perinatal outcome. The association of these measurements with adverse perinatal outcome was assessed. The adverse perinatal outcome was a composite of abnormal condition at birth or major neonatal morbidity.

RESULTS

Adverse perinatal outcome was more frequent among fetuses whose antenatal growth was <100 g/wk, irrespective of signs of cerebral blood flow redistribution. Infants with birthweight <0.65 multiple of the median were enrolled earlier, had the lowest fetal growth velocity, higher umbilical-cerebral ratio, and were more likely to have adverse perinatal outcome. A decreasing fetal growth velocity was observed in 163 (19%) women in whom the estimated fetal weight multiple of the median regression coefficient was <-0.025, and who had higher umbilical-cerebral ratio values and more frequent adverse perinatal outcome; 67 (41%; 8% of total group) of these women had negative growth velocity. Estimated fetal weight and umbilical-cerebral ratio at admission and fetal growth velocity combined by logistic regression had a higher association with adverse perinatal outcome than any of those parameters separately (relative risk, 3.3; 95% confidence interval, 2.3-4.8).

CONCLUSION

In fetuses at risk of late preterm fetal growth restriction, reduced growth velocity is associated with an increased risk of adverse perinatal outcome, irrespective of signs of cerebral blood flow redistribution. Some fetuses showed negative growth velocity, suggesting catabolic metabolism.

Current practice in the diagnosis and management of fetal growth restriction: An international survey

INTRODUCTION

The aim of this survey was to evaluate the current practice in respect of diagnosis and management of fetal growth restriction among obstetricians in different countries.

MATERIAL AND METHODS

An e-questionnaire was sent via REDCap with "click thru" links in emails and newsletters to obstetric practitioners in different countries and settings with different levels of expertise. Clinical scenarios in early and late fetal growth restriction were given, followed by structured questions/response pairings.

RESULTS

A total of 275 participants replied to the survey with 87% of responses complete. Participants were obstetrician/gynecologists (54%; 148/275) and fetal medicine specialists (43%; 117/275), and the majority practiced in a tertiary teaching hospital (56%; 153/275). Delphi consensus criteria for fetal growth restriction diagnosis were used by 81% of participants (223/275) and 82% (225/274) included a drop in fetal growth velocity in their diagnostic criteria for late fetal growth restriction. For early fetal growth restriction, TRUFFLE criteria were used for fetal monitoring and delivery timing by 81% (223/275). For late fetal growth restriction, indices of cerebral blood flow redistribution were used by 99% (250/252), most commonly cerebroplacental ratio (54%, 134/250). Delivery timing was informed by cerebral blood flow redistribution in 72% (176/244), used from ≥32 weeks of gestation. Maternal biomarkers and hemodynamics, as additional tools in the context of early-onset fetal growth restriction (≤32 weeks of gestation), were used by 22% (51/232) and 46% (106/230), respectively.

CONCLUSIONS

The diagnosis and management of fetal growth restriction are fairly homogeneous among different countries and levels of practice, particularly for early fetal growth restriction. Indices of cerebral flow distribution are widely used in the diagnosis and management of late fetal growth restriction, whereas maternal biomarkers and hemodynamics are less frequently assessed but more so in early rather than late fetal growth restriction. Further standardization is needed for the definition of cerebral blood flow redistribution.

Role of umbilicocerebral and cerebroplacental ratios in prediction of perinatal outcome in FGR pregnancies

Purpose

Aim of our study was to compare the prognostic value of the Umbilical-to-Cerebral ratio (UCR) directly to the Cerebroplacental ratio (CPR) in the prediction of poor perinatal outcomes in pregnancies complicated by Fetal Growth Restriction (FGR).

Methods

A retrospective study was carried out on pregnant women with either a small-for-gestational age (SGA) fetus or that were diagnosed with FGR. Doppler measurements of the two subgroups were assessed and the correlation between CPR, UCR and relevant outcome parameters was evaluated by performing linear regression analysis, binary logistic analysis and receiver operator characteristic (ROC) curves. Outcomes of interest were mode of delivery, acidosis, preterm delivery, gestational age at birth as well as birthweight and centiles.

Results

Boxplots and Scatterplots illustrated the different distribution of CPR and UCR leading to deviant correlational relationships with adverse outcome parameters. In almost all parameters examined, UCR showed a higher independent association with preterm delivery (OR: 5.85, CI 2.23–15.34), APGAR score < 7 (OR: 3.52; CI 1.58–7.85) as well as weight under 10th centile (OR: 2.04; CI 0.97–4.28) in binary logistic regression compared to CPR which was only associated with preterm delivery (OR: 0.38; CI 0.22–0.66) and APGAR score < 7 (OR: 0.27; CI 0.06–1.13). When combined with different ultrasound parameters in order to differentiate between SGA and FGR during pregnancy, odds ratios for UCR were highly significant compared to odds ratios for CPR (OR: 0.065, 0.168–0.901; p = 0.027; OR: 0.810, 0.369–1.781; p = 0.601). ROC curves plotted for CPR and UCR showed almost identical moderate prediction performance.

Conclusion

Since UCR is a better discriminator of Doppler values in abnormal range it presents a viable option to Doppler parameters and ratios that are used in clinical practice. UCR and CPR showed equal prognostic accuracy conserning sensitivity and specificity for adverse perinatal outcome, while adding UA PI and GA_scan increased prognostic accuracy regarding negative outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00404-021-06268-4.