Role of Doppler ultrasound at time of diagnosis of late-onset fetal growth restriction in predicting adverse perinatal outcome: prospective cohort study

A Hybrid Model for Fetal Growth Restriction Assessment by Automatic Placental Radiomics on T2-Weighted MRI and Multifeature Fusion

BACKGROUND

MRI-based placental analyses have been used to improve fetal growth restriction (FGR) assessment by complementing ultrasound-based measurements. However, these are still limited by time-consuming manual annotation in MRI data and the lack of mother-based information.

PURPOSE

To develop and validate a hybrid model for accurate FGR assessment by automatic placental radiomics on T2-weighted imaging (T2WI) and multifeature fusion.

STUDY TYPE

Retrospective.

POPULATION

274 pregnant women (29.5  ±  4.0 years) from two centers were included and randomly divided into training (N = 119), internal test (N = 40), time-independent validation (N = 43), and external validation (N = 72) sets.

FIELD STRENGTH/SEQUENCE

1.5-T, T2WI half-Fourier acquisition single-shot turbo spin-echo pulse sequence.

ASSESSMENT

First, the placentas on T2WI were manually annotated, and a deep learning model was developed to automatically segment the placentas. Then, the radiomic features were extracted from the placentas and selected by three-step feature selection. In addition, fetus-based measurement features and mother-based clinical features were obtained from ultrasound examinations and medical records, respectively. Finally, a hybrid model based on random forest was constructed by fusing these features, and further compared with models based on other machine learning methods and different feature combinations.

STATISTICAL TESTS

The performances of placenta segmentation and FGR assessment were evaluated by Dice similarity coefficient (DSC) and the area under the receiver operating characteristic curve (AUROC), respectively. A P-value <0.05 was considered statistically significant.

RESULTS

The placentas were automatically segmented with an average DSC of 90.0%. The hybrid model achieved an AUROC of 0.923, 0.931, and 0.880 on the internal test, time-independent validation, and external validation sets, respectively. The mother-based clinical features resulted in significant performance improvements for FGR assessment.

DATA CONCLUSION

The proposed hybrid model may be able to assess FGR with high accuracy. Furthermore, information complementation based on placental, fetal, and maternal features could also lead to better FGR assessment performance.

LEVEL OF EVIDENCE: 3

TECHNICAL EFFICACY

Stage 2.

Umbilical Vein Flows and Cardiac Size, Shape, and Ventricular Contractility in Fetuses With Estimated Weight Less-Than 10th Centile

OBJECTIVES

In a cohort of patients with estimated fetal weights (EFWs) <10th centile, we aimed 1) to compare the prevalence of abnormalities of fetal 4-chamber view (4CV) cardiac size, shape, and ventricular contractility in fetal growth restricted (FGR) and small-for-gestational-age (SGA) fetuses and 2) to compare umbilical vein flow (UVF) measurements to standard Doppler surveillance in predicting abnormalities of cardiac function.

METHODS

Prospective observational cohort study of fetuses with EFW <10th percentile. Measurements of size and shape used were 4CV transverse width, 4CV cardiac area, 4CV global sphericity index, and right-to-left ventricular mid-chamber width ratio. Variables of contractility used were fractional shortening change at the mid-ventricle chamber, global longitudinal strain, fractional area change, and left ventricular cardiac output. The UVF and standard Doppler surveillance including umbilical artery (UA), middle cerebral artery, and cerebroplacental ratio (CPR) were collected. Control data were from previously published studies.

RESULTS

A total of 95 fetuses with EFWs <10th centile were included in the study. The rates of abnormalities of cardiac size and shape and ventricular contractility were all significantly elevated compared with normally grown control fetuses but similar between FGR and SGA fetuses. In a subset of 76 patients with UVF data, evaluation UVF identified more patients with any abnormality of contractility compared with UA (37.9 vs 17.2%, P = .02).

CONCLUSIONS

The addition of UVF doubled the detection rate of ventricular contractility abnormalities. The addition of UVF should be considered in the surveillance of FGR and SGA fetuses to further stratify the severity of hypoxemia and to identify those at greater risk for future cardiovascular dysfunction.

Prediction of intrapartum fetal compromise at the end of pregnancy; is Doppler, and not weight, that matters

Despite the fact that labor depends on too many interacting factors and no parameter can fully predict its outcome, fetal cerebral Doppler has emerged as the most reliable tool for prediction, in contrast with fetal weight, which performs significantly worse in the last weeks of pregnancy. The importance of the cerebral Doppler follows the inverse pathway of fetal weight increasing its performance in the last weeks of pregnancy and reaching its highest ability prior to labor. A combination of cerebral flow, fetal weight, and selected clinical information may obtain moderate predictions of labor outcome, provided the interval to labor is not long.

Role of Inflammatory Markers and Doppler Parameters in Late-Onset Fetal Growth Restriction: A Machine-Learning Approach

OBJECTIVES

This study evaluates the association of novel inflammatory markers and Doppler parameters in late-onset FGR (fetal growth restriction), utilizing a machine-learning approach to enhance predictive accuracy.

MATERIALS AND METHODS

A retrospective case-control study was conducted at the Department of Perinatology, Ministry of Health Etlik City Hospital, Ankara, from 2023 to 2024. The study included 240 patients between 32 and 37 weeks of gestation, divided equally between patients diagnosed with late-onset FGR and a control group. We focused on novel inflammatory markers-systemic immune-inflammation index (SII), systemic inflammatory response index (SIRI), and neutrophil-percentage-to-albumin ratio (NPAR)-and their correlation with Doppler parameters of umbilical and uterine arteries. Machine-learning algorithms were employed to analyze the data collected, including demographic, neonatal, and clinical parameters, to develop a predictive model for FGR.

RESULTS

The machine-learning model, specifically the Random Forest algorithm, effectively integrated the inflammatory markers with Doppler parameters to predict FGR. NPAR showed a significant correlation with FGR presence, providing a robust tool in the predictive model (Accuracy 77%, area under the curve [AUC] 0.851). In contrast, SII and SIRI, while useful, did not achieve the same level of predictive accuracy (Accuracy 75% AUC 0.818 and Accuracy 73% AUC 0.793, respectively). The model highlighted the potential of combining ultrasound measurements with inflammatory markers to improve diagnostic accuracy for late-onset FGR.

CONCLUSIONS

This study illustrates the efficacy of integrating machines with traditional diagnostic methods to enhance the prediction of late-onset FGR. Further research with a larger cohort is recommended to validate these findings and refine the predictive model, which could lead to improved clinical outcomes for affected pregnancies.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT06372938.

Association between Doppler assessment and secondary cesarean delivery for intrapartum fetal compromise in small-for-gestational-age fetuses

PURPOSE

To elucidate the association between arterial and venous Doppler ultrasound parameters and the risk of secondary cesarean delivery for intrapartum fetal compromise (IFC) and neonatal acidosis in small-for-gestational-age (SGA) fetuses.

METHODS

This single-center, prospective, blinded, cohort study included singleton pregnancies with an estimated fetal weight (EFW) < 10th centile above 36 gestational weeks. Upon study inclusion, all women underwent Doppler ultrasound, including umbilical artery (UA) pulsatility index (PI), middle cerebral artery (MCA) PI, fetal aortic isthmus (AoI) PI, umbilical vein blood flow (UVBF), and modified myocardial performance index (mod-MPI). Primary outcome was defined as secondary cesarean section due to IFC.

RESULTS

In total, 87 SGA pregnancies were included, 16% of which required a cesarean section for IFC. Those fetuses revealed lower UVBF corrected for abdominal circumference (AC) (5.2 (4.5-6.3) vs 7.2 (5.5-8.3), p = 0.001). There was no difference when comparing AoI PI, UA PI, ACM PI, or mod-MPI. No association was found for neonatal acidosis. After multivariate logistic regression, UVBF/AC remained independently associated with cesarean section due to IFC (aOR 0.61 [0.37; 0.91], p = 0.03) and yielded an area under the curve (AUC) of 0.78 (95% CI, 0.67-0.89). A cut-off value set at the 50th centile of UVBF/AC reached a sensitivity of 86% and specificity of 58% for the occurrence of cesarean section due to IFC (OR 8.1; 95% CI, 1.7-37.8, p = 0.003).

CONCLUSION

Low levels of umbilical vein blood flow (UVBF/AC) were associated with an increased risk among SGA fetuses to be delivered by cesarean section for IFC.

Fetal MRI-Based Body and Adiposity Quantification for Small for Gestational Age Perinatal Risk Stratification

BACKGROUND

Small for gestational age (SGA) fetuses are at risk for perinatal adverse outcomes. Fetal body composition reflects the fetal nutrition status and hold promise as potential prognostic indicator. MRI quantification of fetal anthropometrics may enhance SGA risk stratification.

HYPOTHESIS

Smaller, leaner fetuses are malnourished and will experience unfavorable outcomes.

STUDY TYPE

Prospective.

POPULATION

40 SGA fetuses, 26 (61.9%) females: 10/40 (25%) had obstetric interventions due to non-reassuring fetal status (NRFS), and 17/40 (42.5%) experienced adverse neonatal events (CANO). Participants underwent MRI between gestational ages 30 + 2 and 37 + 2.

FIELD STRENGTH/SEQUENCE

3-T, True Fast Imaging with Steady State Free Precession (TruFISP) and T1-weighted two-point Dixon (T1W Dixon) sequences.

ASSESSMENT

Total body volume (TBV), fat signal fraction (FSF), and the fat-to-body volumes ratio (FBVR) were extracted from TruFISP and T1W Dixon images, and computed from automatic fetal body and subcutaneous fat segmentations by deep learning. Subjects were followed until hospital discharge, and obstetric interventions and neonatal adverse events were recorded.

STATISTICAL TESTS

Univariate and multivariate logistic regressions for the association between TBV, FBVR, and FSF and interventions for NRFS and CANO. Fisher's exact test was used to measure the association between sonographic FGR criteria and perinatal outcomes. Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated. A P-value <0.05 was considered statistically significant.

RESULTS

FBVR (odds ratio [OR] 0.39, 95% confidence interval [CI] 0.2-0.76) and FSF (OR 0.95, CI 0.91-0.99) were linked with NRFS interventions. Furthermore, TBV (OR 0.69, CI 0.56-0.86) and FSF (OR 0.96, CI 0.93-0.99) were linked to CANO. The FBVR sensitivity/specificity for obstetric interventions was 85.7%/87.5%, and the TBV sensitivity/specificity for CANO was 82.35%/86.4%. The sonographic criteria sensitivity/specificity for obstetric interventions was 100%/33.3% and insignificant for CANO (P = 0.145).

DATA CONCLUSION

Reduced TBV and FBVR may be associated with higher rates of obstetric interventions for NRFS and CANO.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 5.

Diagnosis, Prevention, and Management of Fetal Growth Restriction (FGR)

Fetal growth restriction (FGR), or intrauterine growth restriction (IUGR), is still the second most common cause of perinatal mortality. The factors that contribute to fetal growth restriction can be categorized into three distinct groups: placental, fetal, and maternal. The prenatal application of various diagnostic methods can, in many cases, detect the deterioration of the fetal condition in time because the nature of the above disorder is thoroughly investigated by applying a combination of biophysical and biochemical methods, which determine the state of the embryo-placenta unit and assess the possible increased risk of perinatal failure outcome and potential for many later health problems. When considering the potential for therapeutic intervention, the key question is whether it can be utilized during pregnancy. Currently, there are no known treatment interventions that effectively enhance placental function and promote fetal weight development. Nevertheless, in cases with fetuses diagnosed with fetal growth restriction, immediate termination of pregnancy may have advantages not only in terms of minimizing perinatal mortality but primarily in terms of reducing long-term morbidity during childhood and maturity.

Effects of umbilical vein flow on midbrain growth and cortical development in late onset fetal growth restricted fetuses: a prospective cross-sectional study

OBJECTIVES

To investigate midbrain growth, including corpus callusum (CC) and cerebellar vermis (CV) and cortical development in late fetal growth restricted (FGR) subclassified according to the umbilical vein blood flow (UVBF) values.

METHODS

This was a prospective study on singleton fetuses late FGR with abnormal placental cerebral ratio (PCR). FGR fetuses were further subdivided into normal (≥fifth centile) and abnormal (

RESULTS

The study cohort included 60 late FGR, 31 with normal UVBF/AC and 29 with abnormal UVBF/AC values. The latter group showed significant differences in CC (median (interquartile range (IQR) normal 0.96 (0.73-1.16) vs. abnormal UVBF/AC 0.60 (0.47-0.87); p<0.0001)), CV (normal 1.04 (0.75-1.26) vs. abnormal UVBF (AC 0.76 (0.62-1.18)); p=0.0319), SF (normal 0.83 (0.74-0.93) vs. abnormal UVBF/AC 0.56 (0.46-0.68); p<0.0001), POF (normal 0.80 (0.71-0.90) vs. abnormal UVBF/AC l 0.49 (0.39-0.90); p≤0.0072) and CF (normal 0.83 (0.56-1.01) vs. abnormal UVBF/AC 0.72 (0.53-0.80); p<0.029).

CONCLUSIONS

Late onset FGR fetuses with of reduced umbilical vein flow showed shorter CC and CV length and a delayed cortical development when compared to those with normal umbilical vein hemodynamics. These findings support the existence of a link between abnormal brain development and changes in umbilical vein circulation.

Collapse

Key Words

• cerebellar vermis
• corpus callosum
• cortical folding
• fetal growth restriction
• neurosonography
• umbilical vein flow

Collapse

MESH Headings

• Humans
• Female
• Fetal Growth Retardation/diagnostic imaging
• Fetal Growth Retardation/physiopathology
• Pregnancy
• Prospective Studies
• Cross-Sectional Studies
• Umbilical Veins/diagnostic imaging
• Adult
• Ultrasonography, Prenatal/methods
• Mesencephalon/diagnostic imaging
• Mesencephalon/blood supply
• Mesencephalon/embryology
• Fetal Development/physiology
• Cerebral Cortex/diagnostic imaging
• Cerebral Cortex/blood supply
• Cerebral Cortex/embryology

Collapse

Grants Collapse

Affiliation(s)

Ilenia Mappa Department of Obstetrics and Gynecology, Fondazione Policlinico Tor Vergata, Università di Roma Tor Vergata, Rome, Italy
Maria Chiara Marra Department of Obstetrics and Gynecology, Fondazione Policlinico Tor Vergata, Università di Roma Tor Vergata, Rome, Italy
Maria Elena Pietrolucci Department of Obstetrics and Gynecology, Fondazione Policlinico Tor Vergata, Università di Roma Tor Vergata, Rome, Italy
Jia Li Angela Lu Department of Obstetrics and Gynecology, Fondazione Policlinico Tor Vergata, Università di Roma Tor Vergata, Rome, Italy
Francesco D'Antonio Department of Obstetrics and Gynecology, Università di Chieti, Chieti, Italy
Giuseppe Rizzo Department of Obstetrics and Gynecology, Fondazione Policlinico Tor Vergata, Università di Roma Tor Vergata, Rome, Italy Department of Obstetrics and Gynecology, Università di Chieti, Chieti, Italy

Collapse

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.

Intrauterine Growth Restriction: Need to Improve Diagnostic Accuracy and Evidence for a Key Role of Oxidative Stress in Neonatal and Long-Term Sequelae

Intrauterine growth restriction (IUGR) and being small for gestational age (SGA) are two distinct conditions with different implications for short- and long-term child development. SGA is present if the estimated fetal or birth weight is below the tenth percentile. IUGR can be identified by additional abnormalities (pathological Doppler sonography, oligohydramnion, lack of growth in the interval, estimated weight below the third percentile) and can also be present in fetuses and neonates with weights above the tenth percentile. There is a need to differentiate between IUGR and SGA whenever possible, as IUGR in particular is associated with greater perinatal morbidity, prematurity and mortality, as well as an increased risk for diseases in later life. Recognizing fetuses and newborns being "at risk" in order to monitor them accordingly and deliver them in good time, as well as to provide adequate follow up care to ameliorate adverse sequelae is still challenging. This review article discusses approaches to differentiate IUGR from SGA and further increase diagnostic accuracy. Since adverse prenatal influences increase but individually optimized further child development decreases the risk of later diseases, we also discuss the need for interdisciplinary follow-up strategies during childhood. Moreover, we present current concepts of pathophysiology, with a focus on oxidative stress and consecutive inflammatory and metabolic changes as key molecular mechanisms of adverse sequelae, and look at future scientific opportunities and challenges. Most importantly, awareness needs to be raised that pre- and postnatal care of IUGR neonates should be regarded as a continuum.

A longitudinal study on the effect of obesity upon circulating renin-angiotensin system in normal pregnancy

BACKGROUND AND AIMS

Obesity is the most common health issue in women of reproductive age, which profoundly affects maternal-fetal health. Despite progress in understanding key inflammatory and metabolic changes, the pathogenesis of the cardiovascular phenotype of obese pregnant women remains to be fully understood. This study aimed at: (i) evaluating the changes of the renin-angiotensin system (RAS) throughout pregnancy in obese vs normal weight (control) women, and (ii) evaluating the presence of any associations between maternal hemodynamic status and RAS changes.

METHODS AND RESULTS

Thirty-eight normal weight and nineteen obese pregnant women were included. Clinical assessment, blood samples and maternal hemodynamic evaluation were performed at 12, 20, 30, and 36 weeks, while ultrasound assessment was scheduled at 20, 30, and 36 weeks of gestation. Measurements of sFlt-1, PlGF, Angiotensinogen, Renin, AngII, Ang1-7, ACE and ACE2 were performed by ELISA. Our data show that normotensive obese women had lower placental blood supply, as assessed by UV-Q and UV-Q/EFW, as compared to controls, and significantly higher levels of AngII and AngII/Ang1-7 ratio, which were inversely related to placental blood supply.

CONCLUSIONS

Our study shows for the first time that normotensive obese women exhibited a significant progressive increase of AngII and AngII/Ang1-7 throughout pregnancy, which were inversely related to placental blood supply as assessed by UV-Q and UV-Q/EFW. Our data shed light on the early changes in pregnant obese women and suggest that RAS dysregulation is a prerequisite rather than a consequence of hypertensive disorders of pregnancy and other maternal neonatal complications.

Deep learning-based segmentation of whole-body fetal MRI and fetal weight estimation: assessing performance, repeatability, and reproducibility

OBJECTIVES

To develop a deep-learning method for whole-body fetal segmentation based on MRI; to assess the method's repeatability, reproducibility, and accuracy; to create an MRI-based normal fetal weight growth chart; and to assess the sensitivity to detect fetuses with growth restriction (FGR).

METHODS

Retrospective data of 348 fetuses with gestational age (GA) of 19-39 weeks were included: 249 normal appropriate for GA (AGA), 19 FGR, and 80 Other (having various imaging abnormalities). A fetal whole-body segmentation model with a quality estimation module was developed and evaluated in 169 cases. The method was evaluated for its repeatability (repeated scans within the same scanner, n = 22), reproducibility (different scanners, n = 6), and accuracy (compared with birth weight, n = 7). A normal MRI-based growth chart was derived.

RESULTS

The method achieved a Dice = 0.973, absolute volume difference ratio (VDR) = 1.8% and VDR mean difference = 0.75% ([Formula: see text]: - 3.95%, 5.46), and high agreement with the gold standard. The method achieved a repeatability coefficient = 4.01%, ICC = 0.99, high reproducibility with a mean difference = 2.21% ([Formula: see text]: - 1.92%, 6.35%), and high accuracy with a mean difference between estimated fetal weight (EFW) and birth weight of - 0.39% ([Formula: see text]: - 8.23%, 7.45%). A normal growth chart (n = 246) was consistent with four ultrasound charts. EFW based on MRI correctly predicted birth-weight percentiles for all 18 fetuses ≤ 10thpercentile and for 14 out of 17 FGR fetuses below the 3rd percentile. Six fetuses referred to MRI as AGA were found to be < 3rd percentile.

CONCLUSIONS

The proposed method for automatic MRI-based EFW demonstrated high performance and sensitivity to identify FGR fetuses.

CLINICAL RELEVANCE STATEMENT

Results from this study support the use of the automatic fetal weight estimation method based on MRI for the assessment of fetal development and to detect fetuses at risk for growth restriction.

KEY POINTS

• An AI-based segmentation method with a quality assessment module for fetal weight estimation based on MRI was developed, achieving high repeatability, reproducibility, and accuracy. • An MRI-based fetal weight growth chart constructed from a large cohort of normal and appropriate gestational-age fetuses is proposed. • The method showed a high sensitivity for the diagnosis of small fetuses suspected of growth restriction.

Two-Compartment Perfusion MR IVIM Model to Investigate Normal and Pathological Placental Tissue

BACKGROUND

Perfusion and diffusion coexist in the placenta and can be altered by pathologies. The two-perfusion model, where f1 and, f2 are the perfusion-fraction of the fastest and slowest perfusion compartment, respectively, and D is the diffusion coefficient, may help differentiate between normal and impaired placentas.

PURPOSE

Investigate the potential of the two-perfusion IVIM model in differentiating between normal and abnormal placentas.

STUDY-TYPE

Retrospective, case-control.

POPULATION

43 normal pregnancy, 9 fetal-growth-restriction (FGR), 6 small-for-gestational-age (SGA), 4 accreta, 1 increta and 2 percreta placentas.

FIELD STRENGTH/SEQUENCE

Diffusion-weighted-echo planar imaging sequence at 1.5 T.

ASSESSMENT

Voxel-wise signal-correction and fitting-controls were used to avoid overfitting obtaining that two-perfusion model fitted the observed data better than the IVIM model (Akaike weight: 0.94). The two-perfusion parametric-maps were quantified from ROIs in the fetal and maternal placenta and in the accretion zone of accreta placentas. The diffusion coefficient D was evaluated using a b ≥ 200 sec/mm2 -mono-exponential decay fit. IVIM metrics were quantified to fix f1  + f2  = fIVIM .

STATISTICAL-TESTS

ANOVA with Dunn-Sidák's post-hoc correction and Cohen's d test were used to compare parameters between groups. Spearman's coefficient was evaluated to study the correlation between variables. A P-value<0.05 indicated a statistically significant difference.

RESULTS

There was a significant difference in f1 between FGR and SGA, and significant differences in f2 and fIVIM between normal and FGR. The percreta + increta group showed the highest f1 values (Cohen's d = -2.66). The f2 between normal and percreta + increta groups showed Cohen's d = 1.12. Conversely, fIVIM had a small effective size (Cohen's d = 0.32). In the accretion zone, a significant correlation was found between f2 and GA (ρ = 0.90) whereas a significant negative correlation was found between fIVIM and D (ρ = -0.37 in fetal and ρ = -0.56 in maternal side) and f2 and D (ρ = -0.38 in fetal and ρ = -0.51 in maternal side) in normal placentas.

CONCLUSION

The two-perfusion model provides complementary information to IVIM parameters that may be useful in identifying placenta impairment.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 1.

Fetal and maternal Doppler adaptation to maternal exercise during pregnancy: a randomized controlled trial

BACKGROUND

Regular and supervised exercise during pregnancy is worldwide recommended due to its proven benefits, but, during exercise, maternal blood flow is redirected from the viscera to the muscles and how fetal wellbeing may be affected by this redistribution is still not well known.

OBJECTIVE

To analyze the longitudinal effect of a supervised moderate physical exercise program during pregnancy on uteroplacental and fetal Doppler parameters.

METHODS

This is a planned secondary analysis of an randomized controlled trial (RCT), performed at Hospital Universitario de Torrejón, Madrid, Spain, including 124 women randomized from 12⁺⁰ to 15⁺⁶ weeks of gestation to exercise vs. control group. Fetal umbilical artery (UA), middle cerebral artery, and uterine artery pulsatility index (PI), were longitudinally collected by Doppler ultrasound assessment throughout gestation, and derived cerebroplacental ratio (normalized by z-score), and maternal mean PI in the uterine arteries (normalized by multiplies of the median). Obstetric appointments were scheduled at 12 (baseline, 12⁺⁰ to 13⁺⁵), 20 (19⁺⁰ to 24⁺²), 28 (26⁺³ to 31⁺³) and 35 weeks (32⁺⁶ to 38⁺⁶) of gestation. Generalized estimating equations were adjusted to assess longitudinal changes in the Doppler measurements according to the randomization group.

RESULTS

No significant differences in the fetal or maternal Doppler measurements were found at any of the different checkup time points studied. The only variable that consistently affected the Doppler standardized values was gestational age at the time of assessment. The evolution of the UA PI z-score during the pregnancy was different in the two study groups, with a higher z-score in the exercise group at 20 weeks and a subsequent decrease until delivery while in the control group it remained stable at around zero.

CONCLUSIONS

A regular supervised moderate exercise program during pregnancy does not deteriorate fetal or maternal ultrasound Doppler parameters along the pregnancy, suggesting that the fetal well-being is not compromised by the exercise intervention. Fetal UA PI z-score decreases during pregnancy to lower levels in the exercise group compared with the control group.

Usefulness of angiogenic factors in prenatal counseling of late-onset fetal growth-restricted and small-for-gestational-age gestations: a prospective observational study

OBJECTIVES

To create a predictive model including biomarkers and evaluate its ability to predict adverse perinatal outcomes in late-onset small fetuses, ultimately helping to provide individualized counseling at the time of diagnosis.

METHODS

This was a prospective observational study, including singleton pregnancies with an estimated fetal weight (EFW) below the 10th percentile, at a gestational age between 32 + 0 and 36 + 6 weeks of gestation (WG). Variables recorded at diagnosis to predict adverse pregnancy outcomes were: soluble fms-like tyrosine-kinase-1 to placental growth factor ratio (sFlt-1/PlGF), fetal Doppler (umbilical artery and middle cerebral artery), uterine artery pulsatility index (UtAPI), EFW percentile, gestational age, and the presence of maternal risk factors for placental insufficiency. Logistic regression models were developed for the prediction of three co-primary outcomes: composite adverse perinatal outcomes (APO), and the need for elective delivery before 35 or 37 WG.

RESULTS

Sixty (52.2%) fetal growth restricted (FGR) and 55 (47.8%) small for gestational age (SGA) were enrolled. Thirteen (11.3%) women needed elective delivery before 35 WG and 27 (23.5%) women before 37 WG. At least one APO occurred in 43 (37.4%) pregnancies. The best marker in univariate analyses was the sFlt-1/PlGF ratio [AUC = 0.932 (95% CI, 0.864-0.999)]. The multivariate model including sFlt-1/PlGF showed a better predictive performance for APO than the multivariate model without sFlt-1/PlGF (P < 0.024).

CONCLUSIONS

sFlt-1/PlGF is a good predictor of APO at the time of late-onset FGR/SGA diagnosis. Our predictive models may be useful to provide early individualized prenatal counseling in this group of women. Further studies are needed to validate these preliminary findings in a larger cohort.

Third-trimester uterine artery Doppler for prediction of adverse outcome in late small-and adequate for-gestational-age fetuses

Fetal growth restriction includes all those fetuses that do not reach their own growth potential due to placental insufficiency and therefore at higher risk of adverse perinatal outcomes. Identification and follow-up of these fetuses is essential to decrease this additional risk. Although estimated fetal weight under the 3rd centile and pathological cerebroplacental ratio are the most accepted predictive criteria, some evidence suggests that abnormal uterine artery Doppler may be a useful prognostic parameter in late-onset growth restriction fetuses at the moment of diagnosis. However, its prediction capacity as a standalone parameter is limited. In that context, integrated models of biometric and hemodynamic ultrasound parameters including uterine Doppler have been proposed as an effective approach to stratify the risk and improve perinatal outcomes. Moreover, an association of abnormal uterine artery Doppler and histological findings of placental underperfusion due to vascular obstruction has been described. Finally, it has also been suggested that the evaluation of uterine artery Doppler at third trimester in appropriate-for-gestational-age fetuses could identify cases of subclinical placental insufficiency, but further evidence is needed to define such predictive strategies.

Added value of the pulmonary vein pulsatility index and its correlation to neonatal umbilical artery pH in fetal growth restrictions: a Vietnamese matched cohort study

BACKGROUND

In clinical obstetrics, many guidelines recommended the use of Doppler fetal ductus venosus blood flow to monitor and to manage fetal growth restriction (FGR). The ductus venosus and the pulmonary venous flow pattern of fetuses are similar. Umbilical artery pH (UA pH) is essential in identifying adverse pregnancy outcomes, particularly in fetal growth restriction cases. Nevertheless, the literature indicates that the relationship between pulmonary vein pulsatility index (PVPI) and UA pH in FGR cases has not been well investigated. This study aimed to identify the alteration in PVPI in FGR cases and evaluate the correlation between PVPI and UA pH in FGR newborns.

METHODS

This matched cohort study of singleton pregnancies from 28+ 0 to 40+ 0 weeks of gestation without congenital abnormalities included 135 cases of FGR (disease group) and 135 cases of normal growth (control group). The PVPI was measured at the proximal segment of the right or left pulmonary vein, approximately 5 mm from the left atrium wall. The umbilical artery pulsatility index (UAPI) was measured on the free umbilical cord. An elective cesarean section or labor induction are both options for ending the pregnancy, depending on the condition of the mother or fetus. Umbilical artery blood samples were collected within 5 min of delivery for UA pH measurement. SPSS version 20 and Medcalc version 20.1 were used for data analysis.

RESULTS

FGR cases had a significantly higher mean fetal PVPI than the control group (1.16 ± 0.26 vs. 0.84 ± 0.16; p < 0.01), and PVPI and UAPI were positively correlated (r = 0.63; p < 0.001). PVPI and UA pH were negatively correlated in FGR patients, with r = -0.68; p < 0.001. The PVPI value on the 95th percentile had a prognostic value of UA pH < 7.20 with a sensitivity of 88.2%, specificity of 66.3%, positive predictive value of 46.9%, and negative predictive value of 94.3%.

CONCLUSIONS

There was a statistically significant difference in PVPI values in FGR cases compared to the normal growth group, a positive correlation between PVPI and UAPI, and a negative correlation between PVPI and UA pH. PVPI might have a prognostic meaning in predicting UA pH at birth.

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.

Fetal Growth Restriction Is Associated with Pregnancy Associated Plasma Protein A and Uterine Artery Doppler in First Trimester

Fetal growth restriction (FGR) is a major cause of stillbirth and poor neurodevelopmental outcomes. The early prediction may be important to establish treatment options and improve neonatal outcomes. The aim of this study was to assess the association of parameters used in first-trimester screening, uterine artery Doppler pulsatility index and the development of FGR. In this retrospective cohort study, 1930 singleton pregnancies prenatally diagnosed with an estimated fetal weight under the third percentile were included. All women underwent first-trimester screening assessing maternal serum pregnancy-associated plasma protein A (PAPP-A), free beta-human chorionic gonadotrophin levels, fetal nuchal translucency and uterine artery Doppler pulsatility index (PI). We constructed a Receiver Operating Characteristics curve to calculate the sensitivity and specificity of early diagnosis of FGR. In pregnancies with FGR, PAPP-A was significantly lower, and uterine artery Doppler pulsatility index was significantly higher compared with the normal birth weight group (0.79 ± 0.38 vs. 1.15 ± 0.59, p < 0.001 and 1.82 ± 0.7 vs. 1.55 ± 0.47, p = 0.01). Multivariate logistic regression analyses demonstrated that PAPP-A levels and uterine artery Doppler pulsatility index were significantly associated with FGR (p = 0.009 and p = 0.01, respectively). To conclude, these two parameters can predict FGR < 3rd percentile.

Umbilical vein blood flow: State-of-the-art

Placental blood supply to the fetus can be measured by evaluating the umbilical vein blood flow. Despite its potential application in healthcare, the umbilical vein blood flow volume is still used only in research setting. One of the reasons is a concern regarding its reproducibility, partly due to technology issues. Nowadays, technology improvements make this evaluation accurate and reproducible. The aim of this review is to refresh basic elements of the physiology of umbilical vein blood flow and its analysis. Its evaluation in normal and abnormal fetal growth is also discussed.

Umbilical Venous Volume Flow in Late-Onset Fetal Growth Restriction

OBJECTIVES

Umbilical vein flow (UVF) is reduced in fetal growth restriction (FGR). We compared absolute and size-adjusted UVF (estimated fetal weight [EFW] and abdominal circumference [AC]) and rates of abnormal UVF parameters (<10th percentile) among FGR fetuses meeting Delphi criteria (FGR-D) against small for gestational age (SGA) fetuses and appropriate for gestational age (AGA) controls.

METHODS

Absolute UVF, UVF/EFW, and UVF/AC were compared between 73 FGR pregnancies (35 FGR-D, 38 SGA) and 108 AGA controls. Rates of abnormal UVF were compared to abnormal umbilical artery pulsatility index (UAPI). Independent samples t-tests, Mann-Whitney U, odds ratio (OR), chi-squared, and Fisher's exact tests were used as appropriate.

RESULTS

Mean absolute UVF was significantly decreased in FGR-D compared to AGA (P = .0147), but not between SGA and AGA fetuses. The incidence of both abnormal absolute UVF and UVF/AC values (<10th centile) was higher among late-onset FGR fetuses versus AGA fetuses (UVF: OR 2.7, confidence interval [CI] 1.37-5.4; UVF/AC: OR 2.73, CI 1.37-5.4). UVF was more frequently abnormal than UAPI and in only two fetuses were both Doppler values abnormal.

CONCLUSION

Absolute UVF is altered in late-onset FGR, and most pronounced among FGR-D. UVF may provide additional insight into fetal compromise in those affected by growth restriction.

Uteroplacental-Cerebral Ratio: A Doppler Parameter for Prognostic Prediction of Late-Onset Fetal Growth Restriction: Single Center Prospective Cohort Study

Purpose: This study aimed to elucidate the accuracy of Doppler parameters in predicting the prognosis of late-onset fetal growth restriction (FGR). Methods: This was a prospective study of 114 pregnancies. Doppler parameters, including the cerebroplacental ratio and pulsatility index (PI) in the middle cerebral, umbilical, uterine artery, were recorded. The new uteroplacental−cerebro ratio (UPCR) was constructed as the ratio of (umbilical artery + mean of the left and right uterine artery) to middle cerebral artery PI. Logistic regression analyses and receiver operating characteristic curves were performed. Results: Adverse outcomes occurred in 37 (32%) neonates. The z values of the middle cerebral artery PI and cerebroplacental ratio were lower (p < 0.001), while the z values of the umbilical artery PI, mean uterine artery PI, and UPCR (p < 0.001) were higher in late-onset FGR in those with compared to those without adverse outcomes. Multivariate logistic regression revealed that only UPCR was independently associated with adverse outcomes (p < 0.001). For predicting the prognosis of late-onset FGR, UPCR showed a fair degree of accuracy (area under the curve [AUC], 0.824). Conclusion: The new UPCR, reflecting the impact of placental impedance from both fetal and maternal sides on fetal well-being, improves the accuracy of prognostic prediction for late-onset FGR.

Role of myocardial performance index (MPI) and cerebro-placental ratio (CPR) in predicting adverse perinatal outcome

INTRODUCTION

This study aimed to evaluate the association of the Myocardial Performance Index (MPI) and Cerebro-Placental Ratio (CPR) in predicting adverse perinatal outcomes in fetuses who are appropriately-grown (AGA), small-for-gestational-age (SGA) and growth restricted (FGR).

METHODS

Singleton pregnancies were recruited after 24 weeks. The patients were recruited after having been classified as AGA (AC/EFW > 10th centile), SGA (AC/EFW-3rd-10th centile without doppler abnormalities), and FGR (AC/EFW < 3rd centile or 3rd-10th centile with doppler abnormalities). A total of 103 cases comprising 48 AGA, 11 SGA, and 44 FGRfetuses were recruited. The Pulsatility Index of the Umbilical artery, Middle cerebral artery, Ductus Venosus, and Aortic Isthmus was obtained. MPI and CPR were calculated too. The primary outcome was to evaluate the predictive value of MPI and CPR for the composite adverse perinatal outcome.

RESULTS

The mean gestational age of recruitment was 30 weeks. The OR for Composite Adverse Perinatal Outcome in FGR group for MPI > .47 and CPR < 1.67 was 3.48 (95% CI: 1.00-12.24, p-value < .05) with sensitivity and specificity of 65% each and 11.08 (95% CI: 2.62-46.83, p-value = .001) with the sensitivity of 82% and specificity of 70%, respectively. When combined together, MPI and CPR yielded an OR of 58.5 (95% CI: 4.58-746.57, p-value = .002) with a sensitivity of 56.5% and specificity of 95% in the FGR group.

CONCLUSIONS

MPI in conjunction with CPR can be used together to predict adverse perinatal outcomes in FGR.

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

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

Modeling gestational age centiles for fetal umbilicocerebral ratio by quantile regression analysis: a secondary analysis of a prospective cross-sectional study

OBJECTIVE

There is a lack of evidence on whether to favor cerebroplacental ratio (CPR) or umbilicocerebral ratio (UCR) when assessing pregnancies at risk of fetal growth restriction. The Recent evidences highlight a significant heterogeneity in the methodology of previously published studies reporting reference ranges for Doppler indices, which may affect the clinical applicability of these charts. The aim of this study was to develop charts of UCR based upon a recently proposed standardized methodology and using quantile regression.

METHODS

This was a secondary analysis of a prospective cross-sectional study including low-risk singleton pregnancies between 24 and 40 weeks of gestation undergoing Doppler recordings. The UCR centile values were established by quantile regression at different gestational age intervals. Quantile regression analysis was used to build the UCR chart.

RESULT

2516 low- risk singleton pregnancies were included in the analysis. UCR decreased with advancing gestational age. The 3rd, 5th 10th, 50th, 90th, 95th, and 97th centiles according to gestational age are provided, as well as equations to allow calculation of any other percentile.

CONCLUSIONS

We have established gestational age-specific normative centiles reference limits for UCR.

Third trimester uterine artery Doppler for prediction of adverse perinatal outcomes

PURPOSE OF REVIEW

Abnormal uterine artery Doppler (UtAD) studies early in gestation have been associated with adverse pregnancy outcomes. However, their association with complications in the third trimester is weak. We aim to review the prediction ability for perinatal complications of these indices in the third trimester.

RECENT FINDINGS

Abnormal UtAD waveforms in the third trimester are associated with preeclampsia, small-for-gestational age infants (SGA), preterm birth, perinatal death, and other perinatal complications, such as cesarean section for fetal distress, 5 min low Apgar score, low umbilical artery pH, and neonatal admission to the ICU, particularly in SGA infants. UtAD prediction performance is improved by the addition of maternal characteristics as well as biochemical markers to prediction models and is more precise if the evaluation is made closer to delivery or diagnosis.

SUMMARY

This review shows that the prediction accuracy of UtAD for adverse pregnancy outcomes during the third trimester is moderate at best. UtAD have limited additive value to prediction models that include PlGF and sFlt-1. Serial assessments rather than a single third trimester evaluation may enhance the prediction performance of the UtAD combined models.

Severe smallness as predictor of adverse perinatal outcome in suspected late small-for-gestational-age fetuses: systematic review and meta-analysis

OBJECTIVE

To investigate the performance of severe smallness in the prediction of adverse perinatal outcome among fetuses with suspected late-onset small-for-gestational age (SGA).

METHODS

A systematic search was performed to identify relevant studies in PubMed, Web of Science and Scopus. Late-onset SGA was defined as estimated fetal weight (EFW) or abdominal circumference (AC) < 10^th percentile diagnosed at or after 32 weeks' gestation, while severe SGA was defined as EFW or AC < 3^rd percentile or < 2 SD. Random-effects modeling was used to generate hierarchical summary receiver-operating-characteristics (HSROC) curves. The performance of severe SGA (as a presumptive diagnosis) in predicting adverse perinatal outcome among singleton pregnancies with suspected late-onset SGA was expressed as area under the HSROC curve (AUC), sensitivity, specificity and positive/negative likelihood ratios. The association between suspected severe SGA and adverse perinatal outcome was also assessed by random-effects modeling using the Mantel-Haenszel method and presented as odds ratio (OR). The non-exposed group was defined as non-severe SGA (EFW ≥ 3^rd centile).

RESULTS

Twelve cohort studies were included in this systematic review and meta-analysis. The studies included a total of 3639 fetuses with suspected late-onset SGA, of which 1246 had suspected severe SGA. Significant associations were found between suspected severe SGA and composite adverse perinatal outcome (OR, 1.97 (95% CI, 1.33-2.92)), neonatal intensive care unit admission (OR, 2.87 (95% CI, 1.84-4.47)) and perinatal death (OR, 4.26 (95% CI, 1.07-16.93)). However, summary ROC curves showed limited performance of suspected severe SGA in predicting perinatal outcomes, with AUCs of 60.9%, 66.9%, 53.6%, 57.2%, 54.6% and 64.9% for composite adverse perinatal outcome, neonatal intensive care unit admission, neonatal acidosis, Cesarean section for intrapartum fetal compromise, low Apgar score and perinatal death, respectively.

CONCLUSION

Although suspected severe SGA was associated with a higher risk of perinatal complications, it performed poorly as a standalone parameter in predicting adverse perinatal outcome. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Value of Cerebroplacental Ratio and Uterine Artery Doppler as Predictors of Adverse Perinatal Outcome in Very Small for Gestational Age at Term Fetuses

The aim of this study was to evaluate the association between cerebroplacental ratio (CPR), mean uterine artery (mUtA) Doppler and adverse perinatal outcome (APO) and their predictive performance in fetuses with birth weight (BW) <3rd centile (very small for gestational age, VSGA) in comparison with fetuses with BW 3rd−10th centile (small for gestational age, SGA). This was a retrospective cohort study including singleton pregnancies delivered at term (37 + 0−41 + 6) in a single tertiary referral center over a six-year period. APO was defined as a composite of cesarean section for intrapartum fetal compromise (IFC), umbilical artery pH < 7.20, and admission to the neonatal intensive care unit for >24 h. The characteristics of the study population according to BW (VSGA and SGA) as well as the presence of composite APO were assessed. The prognostic performance of CPR and mUtA-PI was evaluated using receiver operating characteristic (ROC) analysis. In total, 203 pregnancies were included. Of these, 55 (27%) had CPR <10th centile, 25 (12%) mUtA-PI >95th centile, 65 (32%) VSGA fetuses, and 93 (46%) composite APO. VSGA showed a non-significantly higher rate of composite APO in comparison to SGA (52% vs. 43%; p = 0.202). The composite APO rate was significantly higher in SGA with CPR <10th centile (36% vs. 13%; p = 0.001), while in VSGA with CPR <10th centile was not (38% vs. 35%; p = 0.818). The composite APO rate was non-significantly higher both in VSGA (26% vs. 10%; p = 0.081) and SGA (14% vs. 6%; p = 0.742) with mUtA-PI >95th centile. The ROC analysis showed a significantly predictive value of CPR for composite APO in SGA only (AUC 0.612; p = 0.025). A low CPR was associated with composite APO in SGA fetuses. VSGA fetuses were more frequently affected by composite APO regardless of Doppler values. The predictive performance of CPR and uterine artery Doppler was poor.

Effect of SARS-CoV-2 infection on fetal umbilical vein flow and cardiac function: a prospective study

OBJECTIVES

To explore whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can affect umbilical vein blood flow (UVBF) and fetal cardiac function.

METHODS

Prospective case-control study of consecutive pregnancies complicated by SARS-CoV-2 infection during the second half of pregnancy matched with unaffected women. Measurements of UVBF normalized for fetal abdominal circumference (UVBF/AC), atrial area (AA) and ventricular sphericity indices (SI) were compared between the two study groups. Chi-square and Mann-Whitney U tests were sued to analyze the data.

RESULTS

Fifty-four consecutive pregnancies complicated and 108 not complicated by SARS-CoV-2 infection were included. The median gestational age at infection was 30.2 (interquartile range [IQR] 26.2 34.1). General baseline and pregnancy characteristics were similar between pregnant women with compared to those without SARS-CoV-2 infection. There was no difference in UVBF/AC (study groups z value -0.11 vs. 0.14 control p 0.751) values between pregnancies complicated compared to those not complicated by SARS-CoV-2 infection. Likewise, there was no difference in the left and right AA (left 1.30 vs. 1.28 p=0.221 and right 1.33 vs. 1.31 p=0.324) and SI (left 1.75 vs. 1.77 p=0.208 and right 1.51 vs. 1.54 p=0.121) between the two groups.

CONCLUSIONS

SARS-CoV-2 infection does not affect UVBF and fetal cardiac function in uncomplicated pregnancies.

Modeling Pulsatility Index nomograms from different maternal and fetal vessels by quantile regression at 24-40 weeks of gestation: a prospective cross-sectional study

OBJECTIVE

Recent evidences highlight a considerable heterogeneity in the methodology of previously published studies reporting reference ranges for maternal and fetal Dopplers, which may have relevant implications in clinical practice. In view of these limitations, a standardized methodology to construct Doppler charts has been proposed. The aim of this study was to develop charts for pulsatility index (PI) of maternal and fetal Dopplers based upon the recently proposed standardized methodology and using quantile regression.

METHODS

Prospective cross-sectional study including 2516 low-risk singleton pregnancies between 24 and 40 weeks of gestation. The mean uterine, umbilical (UA), middle cerebral (MCA) and their ratio (cerebroplacental ratio, CPR) centile values were established by quantile regression in the considered gestational interval. Interclass correlation coefficient (ICC) of each maternal and fetal vessel was also computed to assess the intra- and inter-observer agreement of the results.

RESULTS

There was a good intra- and inter-observer agreement for each of the explored vessels (ICC >0.92 and >0.91 for a single and two observers, respectively). The 5th, 10th, 50th, 90th and 95th centiles of the reference range for gestation were constructed by quantile regression and compared to previously established reference charts. All the Doppler indices significantly changed with gestation. Second-degree polynomial regression models better described the changes with gestation in PCR and MCA PI values while a linear model better predicted the changes of other Doppler indices with advancing gestation. When compared to other studies reporting reference ranges for maternal and fetal Dopplers, the present charts showed similar median values but different distribution from the median.

CONCLUSIONS

We provided prospective charts of maternal and fetal Dopplers based upon a previously proposed standardized methodology and using quantile regression. When compared to previously published studies, these new charts showed similar median values but different deviations from the median which may help in better differentiating cases at higher risk of placental insufficiency and adverse perinatal outcome.

Late-term fetuses with reduced umbilical vein blood flow volume: An under-recognized population at increased risk of growth restriction

OBJECTIVES

To investigate the umbilical vein and uterine arteries blood flow volume (UV-Q, UtA-Q) in late-term pregnancies.

STUDY DESIGN

This was a prospective observational cohort study of singleton pregnancies ≥40 + 0 weeks in which UV-Q and UtA-Q, both absolute and normalized for estimated fetal weight (EFW) values, were evaluated in relation to AC drop of ≥20 percentiles from 20 weeks to term, Doppler signs of fetal cerebral blood flow redistribution and composite adverse perinatal outcome. The presence of neonatal hypoglycaemia and the need of formula milk supplementation were also examined.

RESULTS

The study population comprised 200 women. Fetuses with AC drop (n = 34) had a significantly lower UV-Q and UV-Q/EFW than fetuses without AC drop (n = 166): median UV-Q 184 ml/min (IQR 143-225) vs 233 ml/min (IQR 181-277), p = 0.0006; median UV-Q/EFW 55 ml/min/kg (IQR 42-66) vs 63 ml/min/kg (IQR 48-74), p = 0.03. Fetuses with cerebral blood flow redistribution (n = 48) had a significantly lower UV-Q and UV-Q/EFW than those without (n = 134): median UV-Q 210 ml/min (IQR 155-263) vs 236 ml/min (IQR 184-278), p = 0.04; median UV-Q/EFV 58 ml/min/kg (IQR 45-70) vs 65 ml/min/kg (IQR 50-76), p = 0.04. There was a significant moderate correlation between middle cerebral artery pulsatility index (MCA-PI) and UV-Q and UV-Q/EFW (Spearman Rho -0.20 and -0.20; p = 0.008 and p = 0.006).

CONCLUSIONS

The umbilical vein blood flow volume might have a potential role to identify fetuses with stunted growth in late-term pregnancies.

Predictive role of Doppler indices of cerebral-placental-uterine ratio and umbilico-cerebral ratio for late-onset fetal growth restriction: a prospective cohort study

Predicting late-onset foetal growth restriction (FGR) has proven to be rather challenging. In this study, we propose a new parameter, cerebral-placental-uterine (CPU) ratio and umbilico-cerebral (UC) ratio for this matter. Results of this study which included a total of 227 nulliparous women showed that an increase in CPU ratio (OR = 0.45; 95% CI: 0.23-0.88; p=.020) was associated with lower odds of foetal weight above the 10th percentile at birth. CPU ratio measured at 35-37 weeks of gestation had an AUC of 0.78 (95% CI: 0.58, 0.98), sensitivity of 0.62 (95% CI: 0.24, 0.91) and specificity of 0.90 (95% CI: 0.79, 0.96) for prediction of late-onset FGR, which showed higher accuracy than UC ratio. As some cases of the late-onset FGR are not diagnosed by foetal biometry, it is important to find Doppler parameters that can help us predict these cases and CPU ratio may help physicians in detection of high-risk foetuses that will benefit from earlier intervention. Impact StatementWhat is already known on this subject? Late-onset foetal growth restriction (FGR) defined by an FGR diagnosis after 32 weeks of gestational age, can lead to short- and long-term morbidities and early diagnosis is the key to prevent these complications.What do the results of this study add? Results showed that each unit increase in numeric variables including CP ratio (OR = 0.29, p=.006), and CPU ratio (OR = 0.40, p=.006) was associated with lower odds of the foetal weight above the 10th percentile in the second ultrasound at 35-37 weeks. In other words, CPU ratio can prove to be useful marker in prediction of late-onset FGR.What are the implications of these findings for clinical practice and/or further research? Our prospective cohort study confirms the added value of low CPU ratio, with higher predictive accuracy than UC ratio, in predicting late-onset FGR. Detection of late FGR remains poor, but it is important to prevent stillbirth so further studies on the role of CPU ratio in predicting FGR and perinatal outcomes are needed.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Ultrasound prediction of adverse perinatal outcome at diagnosis of late-onset fetal growth restriction

OBJECTIVE

To evaluate the relationship between Doppler and biometric ultrasound parameters measured at diagnosis and perinatal adverse outcome in a cohort of late-onset growth-restricted (FGR) fetuses.

METHODS

This was a multicenter retrospective study of data obtained between 2014 and 2019 including non-anomalous singleton pregnancies complicated by late-onset FGR (≥ 32 weeks), which was defined either as abdominal circumference (AC) or estimated fetal weight (EFW) < 10^th percentile for gestational age or as reduction of the longitudinal growth of AC by over 50 percentiles compared to ultrasound scan performed between 18 and 32 weeks of gestation. We evaluated the association between sonographic findings at diagnosis of FGR and composite adverse perinatal outcome (CAPO), defined as stillbirth or at least two of the following: obstetric intervention due to intrapartum fetal distress, neonatal acidemia, birth weight < 3^rd percentile and transfer to the neonatal intensive care unit (NICU).

RESULTS

Overall, 468 cases with complete biometric and umbilical, fetal middle cerebral and uterine artery (UtA) Doppler data were included, of which 53 (11.3%) had CAPO. On logistic regression analysis, only EFW percentile was associated independently with CAPO (P = 0.01) and NICU admission (P < 0.01), while the mean UtA pulsatility index (PI) multiples of the median (MoM) > 95^th percentile at diagnosis was associated independently with obstetric intervention due to intrapartum fetal distress (P = 0.01). The model including baseline pregnancy characteristics and the EFW percentile was associated with an area under the receiver-operating-characteristics curve of 0.889 (95% CI, 0.813-0.966) for CAPO (P < 0.001). A cut-off value for EFW corresponding to the 3.95^th percentile was found to discriminate between cases with and those without CAPO, yielding a sensitivity of 58.5% (95% CI, 44.1-71.9%), specificity of 69.6% (95% CI, 65.0-74.0%), positive predictive value of 19.8% (95% CI, 13.8-26.8%) and negative predictive value of 92.9% (95% CI, 89.5-95.5%).

CONCLUSIONS

Retrospective data from a large cohort of late-onset FGR fetuses showed that EFW at diagnosis is the only sonographic parameter associated independently with the occurrence of CAPO, while mean UtA-PI MoM > 95^th percentile at diagnosis is associated independently with intrapartum distress leading to obstetric intervention. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Management of fetal Growth Restriction at term by Angiogenic Factors versus feto-maternal Doppler (GRAFD) to avoid adverse perinatal outcomes: multicenter open-label randomized controlled trial study protocol (Preprint)

Background

Fetal smallness affects 10% of pregnancies. Small fetuses are at a higher risk of adverse outcomes. Their management using estimated fetal weight and feto-maternal Doppler has a high sensitivity for adverse outcomes; however, more than 60% of fetuses are electively delivered at 37 to 38 weeks. On the other hand, classification using angiogenic factors seems to have a lower false-positive rate. Here, we present a protocol for the Fetal Growth Restriction at Term Managed by Angiogenic Factors Versus Feto-Maternal Doppler (GRAFD) trial, which compares the use of angiogenic factors and Doppler to manage small fetuses at term.

Objective

The primary objective is to demonstrate that classification based on angiogenic factors is not inferior to estimated fetal weight and Doppler at detecting fetuses at risk of adverse perinatal outcomes.

Methods

This is a multicenter, open-label, randomized controlled trial conducted in 20 hospitals across Spain. A total of 1030 singleton pregnancies with an estimated fetal weight ≤10th percentile at 36+0 to 37+6 weeks+days will be recruited and randomly allocated to either the control or the intervention group. In the control group, standard Doppler-based management will be used. In the intervention group, cases with a soluble fms-like tyrosine kinase to placental growth factor ratio ≥38 will be classified as having fetal growth restriction; otherwise, they will be classified as being small for gestational age. In both arms, the fetal growth restriction group will be delivered at ≥37 weeks and the small for gestational age group at ≥40 weeks. We will assess differences between the groups by calculating the relative risk, the absolute difference between incidences, and their 95% CIs.

Results

Recruitment for this study started on September 28, 2020. The study results are expected to be published in peer-reviewed journals and disseminated at international conferences in early 2023.

Conclusions

The angiogenic factor–based protocol may reduce the number of pregnancies classified as having fetal growth restriction without worsening perinatal outcomes. Moreover, reducing the number of unnecessary labor inductions would reduce costs and the risks derived from possible iatrogenic complications. Additionally, fewer inductions would lower the rate of early-term neonates, thus improving neonatal outcomes and potentially reducing long-term infant morbidities.

Trial Registration

ClinicalTrials.gov NCT04502823; https://clinicaltrials.gov/ct2/show/NCT04502823

International Registered Report Identifier (IRRID)

DERR1-10.2196/37452

Predictors of adverse perinatal outcome up to 34 weeks, a multivariable analysis study

The objective was to evaluate the best predictors of adverse perinatal outcome (APO) in foetuses examined up to 34 weeks and delivered by spontaneous or induced labour. This was a retrospective study of 129 pregnancies that underwent an ultrasound Doppler examination at 23-34 weeks and entered into labour within 30 days. Cerebroplacental ratio (CPR) and mean uterine artery pulsatility index (mUtA PI) were converted into multiples of the median (MoM) and estimated foetal weight (EFW) into centiles to adjust for gestational age (GA). Sonographic and clinical parameters were evaluated using logistic regression analysis.The multivariable model for the prediction of APO presented a notable accuracy: Detection rate (DR) was 39.5% for a false positive rate (FPR) of 5% and 56.8% for a FPR of 10%, AUC 0.82, p < .0001. Significant predictors were GA, EFW centile, and CPR MoM, but not mUtA PI MoM. Moreover, the type of labour onset did not exert any influence on APO. In conclusion, up to 34 weeks, prediction of APO after spontaneous or induced labour may be done measuring CPR and EFW.IMPACT STATEMENTWhat is already known on this subject? Earlier in pregnancy, foetal growth restriction is caused by placental disease causing progressive hemodynamic changes. These changes have been exhaustively described. Conversely, information about the best predictors of adverse outcome is scarce.What do the results of this study add? The findings of this study show that prior to 34 weeks and up to 1 month before labour, labour outcome might be predicted by gestational age, foetal cerebroplacental ratio (CPR) and estimated foetal weight (EFW).What are the implications of these findings for clinical practice and/or further research? If CPR behaves as a good marker of outcome not only at the end of pregnancy but also earlier in gestation, it might be interrogated along with EFW in foetuses attempting vaginal delivery to determine the risk of adverse outcome.

Detection and clinical outcome of small-for-gestational-age fetuses in the third trimester-A comparison between routine ultrasound examination and examination on indication

INTRODUCTION

Fetal growth restriction is a major risk factor for adverse perinatal outcome. As most of the growth-restricted fetuses are small for gestational age (SGA), an efficient antenatal screening method for SGA fetuses would have a major impact on perinatal health. The aim of this study was to compare the SGA prediction rate achieved with third-trimester routine ultrasound estimation of fetal weight (EFW) with that obtained using ultrasound examination on indication. The secondary aim was to evaluate the clinical outcome in relation to the SGA screening method.

MATERIAL AND METHODS

During 1995-2009, two perinatal centers in southern Sweden offered routine ultrasound examination at 32-34 gestational weeks to 99 265 women with singleton pregnancies. Of these, 59 452 (60%) underwent the ultrasound examination. The other population, comprising 24 868 pregnancies, was cared for in another three centers that used a risk-based method with ultrasound examinations on indication only. Of them, 5792 (23%) underwent ultrasound examination at 32-36 gestational weeks. The deviation in the EFW from the expected one was expressed as the EFW z-score, SGA EFW being defined as the EFW z-score less than -2. SGA prediction ability was assessed by receiver operating characteristic (ROC) curves. Crude and adjusted risk ratios were calculated for selected variables of perinatal outcome when comparing the populations.

RESULTS

The SGA prediction ability for routine ultrasound was high, area under the ROC curve was 0.90 (95% CI 0.89-0.91). For an EFW z-score of -1, the sensitivity was 67.3% and specificity was 90.5% among routinely screened pregnancies; corresponding numbers in the ultrasound on indication population were 34.3% and 96.6%. The screened population had a lower risk of preterm birth, birthweight z-score less than -3, and Apgar score less than 7 at 5 min with adjusted risk ratios 0.87 (95% CI 0.82-0.92), 0.75 (95% CI 0.61-0.92), and 0.77 (95% CI 0.68-0.87), respectively. No difference in perinatal mortality was detected. There were no differences in perinatal outcome between the two subcohorts of infants born SGA.

CONCLUSIONS

Third-trimester routine ultrasound improves the detection of SGA antenatally compared with ultrasound performed on indication, but no convincing improvement in perinatal outcome was identified.

Adverse perinatal outcomes in fetuses with severe late-onset fetal growth restriction

OBJECTIVE

To evaluate perinatal outcomes in fetuses with severe late-onset fetal growth restriction.

METHODS

This was a retrospective and observational cohort study in which pregnant women diagnosed with late-onset fetal growth restriction assisted at perinatal maternity birth from 2010 to 2017 were included. The outcomes were intensive care unit (ICU) admission and perinatal complications, such as neonatal death, intraventricular hemorrhage, periventricular leukomalacia, hypoxic-ischemic encephalopathy, necrotizing enterocolitis, bronchopulmonary dysplasia, and sepsis.

RESULTS

We selected 277 pregnant women, of whom 124 newborns (44.76%) went to the ICU. The chance of a newborn needing ICU decreases by 62, 7, and 9% according to an increase of one gestational week, 1 cm of the abdominal circumference, or 1 cm of the amniotic fluid index, respectively. Oligohydramnios increases the risk of going to the ICU by 2.13 times. The increase in the umbilical artery pulsatility index (PI) Doppler increases the chance of ICU admission by 7.9 times. The normal middle cerebral artery PI Doppler and the normal cerebroplacental ratio reduce the risk of ICU admission.

CONCLUSION

The estimated fetal weight, abdominal circumference, and amniotic fluid index diagnosed severe late-onset fetal growth restriction. With the decrease in middle cerebral artery PI Doppler, there is a greater probability of admission to the ICU, with the most common complications being intraventricular hemorrhage and necrotizing enterocolitis.

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.

Cerebroplacental doppler ratio and perinatal outcome in late-onset foetal growth restriction

The purpose of this study was to determine whether gestational age-specific levels of the cerebroplacental ratio (CPR) as a third-trimester ultrasound marker has benefits in the prediction of perinatal morbidity and mortality on foetuses with late-onset foetal growth restriction (FGR). A retrospective study of singleton pregnancies diagnosed with late-onset FGR was performed. Of 407 pregnancies meeting our inclusion criteria, 313 had normal (Group 1) and 94 had abnormal CPR (Group 2). Both groups were similar in age, gestational age at diagnosis, body mass index and parity. There was a significant association between the presence of oligohydramnios and abnormal CPR. Mean gestational age at delivery and mean neonatal birth weight were significantly lower in Group 2. Neonatal intensive care unit admission, foetal distress, low 5-minute Apgar score <7, and low cord pH < 7.1 rates were significantly higher in Group 2. There was one neonatal death in both groups. Multivariable regression analysis demonstrated that, in the prediction of APO, there was a significant contribution from neonatal birth weight <10th percentile, CPR <5th percentile and oligohydramniosis. Our findings revealed that CPR value less than 5th centile can be used as a predictor of APO in late-onset FGR.IMPACT STATEMENTWhat is already known on this subject? Low cerebroplacetal ratio (CPR) is a marker of failure to reach the growth potential regardless of foetal weight.What do the results of this study add? The CPR can be used as an adequate predictor of adverse perinatal outcome in pregnancies with late-onset foetal growth restriction.What are the implications of these findings for clinical practice and/or further research? Routine calculation and report of CPR during basic ultrasound examination may help to identify foetuses with FR with a higher risk of adverse perinatal outcome. Future prospective studies on pregnancies with FGR with oligohydroamnios or normal amniotic fluid volume should focus on determining CPR threshold.

Macrosomia and fetal growth restriction: evidence for similar extrauterine metabolic risks but with differences in pathophysiology

PURPOSE

To investigate and compare the causes of macrosomia and FGR fetuses, their ultrasound characteristics and the importance of their similar metabolic profile in intrauterine and extrauterine life.

MATERIALS AND METHODS

We searched Pubmed/Google Scholar database up until 15 December 2020 using keywords. Out of the 70 matching results we selected 50 most representative and matching papers.

RESULTS

We found similar causes and metabolic profiles and in both conditions offspring are at increased risk of developing metabolic and cardiovascular diseases in the extrauterine life.

CONCLUSION

Despite similarities of the maternal factors and fetal metabolic profile it is still unknown which of them has worse metabolic status during intrauterine and extrauterine life.

Cerebroplacental ratio and aortic isthmus Doppler in early fetal growth restriction

PURPOSE

To assess the utility of cerebroplacental ratio (CPR) and fetal aortic isthmus (AoI) Doppler in the prediction of perinatal outcome in early fetal growth restriction (FGR).

METHODS

A prospective observational cohort study of 70 early FGR cases was conducted through serial Doppler examinations and findings of the last examination were correlated with perinatal outcome. Doppler blood flow measurements of AoI included end diastolic velocity (EDV), peak systolic velocity (PSV), pulsatility index (PI), resistance index (RI), and isthmic flow index (IFI).

RESULTS

Significant association of CPR and all Doppler indices of AoI with the overall adverse perinatal outcome was seen. The sensitivity of CPR was moderate (63.64%) but higher than most AoI indices. Most AoI Doppler indices (PI, RI, IFI) had higher specificities (100%). AoI PSV and EDV had higher sensitivities than CPR for the prediction of overall adverse perinatal outcome, with AoI PSV having the highest sensitivity (100%).

CONCLUSION

CPR shows significant association and moderate sensitivity for prediction of overall adverse perinatal outcome in early FGR; hence recommended in all cases of early FGR. AoI Doppler also appears to have a role in assessment and decision making in FGR in view of high sensitivity and high specificity of AoI indices in the prediction of perinatal outcome. However, larger studies are required to confirm its utility in the management of early FGR.

Use of an artificial intelligence-based rule extraction approach to predict an emergency cesarean section

Objective

One of the major problems with artificial intelligence (AI) is that it is generally known as a “black box”. Therefore, the present study aimed to construct an emergency cesarean section (CS) prediction system using an AI‐based rule extraction approach as a “white box” to detect the cause for the emergency CS.

Methods

Data were collected from all perinatal records of all delivery outcomes at Osaka Medical College between December 2014 and July 2019. We identified the delivery method for all deliveries after 36 gestational weeks as either (1) vaginal delivery or scheduled CS, or (2) emergency CS. From among these, we selected 52 risk factors to feed into an AI‐based rule extraction algorithm to extract rules to predict an emergency CS.

Results

We identified 1513 singleton deliveries (1285 [84.9%] vaginal deliveries, 228 emergency CS [15.1%]) and extracted 15 rules. We achieved an average accuracy of 81.90% using five‐fold cross‐validation and an area under the receiving operating characteristic curve of 71.46%.

Conclusion

To our knowledge, this is the first study to use interpretable AI‐based rule extraction technology to predict an emergency CS. This system appears to be useful for identifying hidden factors for emergency CS.

This is the first study to construct a prediction system for an emergency cesarean section using an artificial intelligence‐based “white box” rule extraction approach.

Fetal-placental blood flow and neurodevelopment in childhood: population-based neuroimaging study

OBJECTIVE

Antenatal Doppler measurements of the fetal umbilical and cerebral circulations can predict perinatal complications; however, it is unclear if subtle variations in antenatal Doppler measurements are associated with long-term neurodevelopmental outcome. In this study, we examined whether antenatal Doppler measurements of the fetal-placental circulation are associated with cognitive and motor abilities and brain morphology in childhood.

METHODS

To evaluate differences in long-term sequelae across the continuum of the umbilical and cerebral artery circulations in the general population, we utilized a population-based longitudinal cohort study approach. In women from the Generation R study, we measured second- and third-trimester umbilical artery pulsatility index (UA-PI). Children underwent non-verbal intelligence testing at 4-8 years of age, and at 8-12 years they underwent finger-tapping tests to measure fine motor skills, balance beam tests to measure gross motor skills and brain magnetic resonance imaging. We assessed the relationships between prenatal UA-PI and neurodevelopmental outcome using linear regression. We adjusted for child age and sex, maternal age, education, parity and smoking status.

RESULTS

The study sample included 2803 pregnancies. Higher third-trimester UA-PI was associated with poorer fine motor performance (0.41 (95% CI, 0.11-0.70) fewer taps on the finger-tapping test per 1 SD higher UA-PI) and gross motor performance (0.64 (95% CI, 0.20-1.08) fewer steps on the balance beam test per 1 SD higher UA-PI). One SD higher third-trimester UA-PI was also associated with 0.65 (95% CI, 0.04-1.25) points lower intelligence quotient; however, unlike the associations with motor abilities, this finding did not persist after correction for multiple testing. Higher second-trimester UA-PI was associated with smaller brain volume (6.1 (95% CI, 1.0-11.3) cm³ reduction per 1 SD higher UA-PI), but the association did not persist after correction for multiple testing.

CONCLUSION

Higher placental vascular resistance may have mild adverse effects on neurodevelopmental outcome at school age. While these effects are subtle at population level, we encourage future research into the role of early circulation in brain development. This information could be used to develop targeted interventions. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Physiopathology of late-onset fetal growth restriction

Fetal growth restriction (FGR) is defined as the inability of the fetus to reach its potential for genetic determination. FGR can have several causes, including genetic syndromes, chromosomal diseases, and infections; however, a vast majority of cases are probably attributed to impaired uterine and placental circulation. The relationships between abnormal placental development and FGR are complex, and studies are generally few, presenting confounding factors. Damage to the uteroplacental circulation associated with vasculogenesis and villus angiogenesis dysfunction are the main factors involved in subsequent FGR. The main receptors involved in FGR include hypoxia-inducible factor (HIF 1, 2, and 3), vascular endothelial growth factor (VEGF), placental growth factor (PlGF), vascular endothelial growth factor C (VEGF-C), soluble Flt-1, soluble endoglin (Seng), angiopoietin-1 and -2 (Ang-1 and Ang-2), tyrosine kinase receptor 1 (Flt-1), tyrosine kinase receptor 2 (Flt-2), vascular endothelial growth factor receptor (VEGFR) 1, 2 and 3, kinase domain receptor (KDR), and vascular endothelial growth factor receptor A (VEGFR-A). Furthermore, failure in trophoblastic invasion and remodeling of spiral arteries has been associated with FGR owing to poor placental perfusion. There are several possible causes for poor remodeling of spiral arteries, which probably vary on a case-to-case basis. Changes in the placental form, macroscopic and microscopic vascular lesions, inflammation, and genetic changes are also related to FGR. Based on gestational age at diagnosis, FGR can be classified as early- (˂32 weeks) and late-onset (≥32 weeks). Moreover, there exist several theories regarding possible pathophysiological differences between early- and late-onset FGR, with some postulating that it the same disease but at different stages or severity. Another hypothesis suggests that the change in the trophoblastic invasion of spiral arteries would be milder. In this article, we address the main mechanisms described in the pathophysiology of FGR and, later, the specific findings in late-onset FGR.

Induction of labor in late FGR

Late-onset FGR is a peculiar condition characterized by the inability for the fetus to reach its growth potential diagnosed from 32 weeks of gestation. Placental insufficiency is among the leading causes of late FGR and is commonly due to a primary maternal cardiovascular non-adaptation potentially leading to fetal decompensation during labor especially once exposed to uterine hyperstimulation. Abnormalities that usually characterize late FGR include reduced fetal growth, decreased Amniotic Fluid Index, and loss of fetal heart rate variability at CTG. Fetal hemodynamics study by Doppler ultrasound significantly improved management of pregnancies affected by fetal growth restriction. A major issue when dealing with pregnancies complicated by late FGR is how to induce these women. Induction of labor (IOL) can be essentially accomplished by pharmacological and non-pharmacological agents. Recent studies suggested that the pregnancies complicated by late FGR should undergo a tailored approach for IOL in view of the higher risk of fetal decompensation following uterine hyperstimulation. The present review aims to provide an up to date on the different types of IOL which can guide clinical management.

Distinction between SGA and FGR by means of fetal umbilical vein flow and maternal hemodynamics

OBJECTIVES

To improve identification of fetal growth restriction (FGR) by means of umbilical venous flow (QUV) and maternal hemodynamics, including systemic vascular resistance (SVR) and cardiac output (CO), in order to distinguish between FGR and SGA.

METHODS

We enrolled 68 pregnancies (36 SGA, 8 early FGR and 24 late FGR) who underwent a complete fetal hemodynamic examination including QUV and a noninvasive maternal hemodynamics assessment by means of USCOM.

RESULTS

In comparison with SGA, QUV and corrected for estimated fetal weight QUV (cQUV) were significantly lower in early and late-FGR. In addition, maternal CO was lower in early and late-FGR, while SVR was lower only in early-onset FGR. According to ROC analysis, cQUV centile (AUC 0.92, 0.72) was the best parameter for the prediction of SGA before and after 32 weeks, followed by SVR and CO. For all parameters, the prediction was always better in the case of early-onset FGR <32 weeks.

CONCLUSIONS

UV flow and maternal hemodynamics examination are useful tools to accurately discern between SGA and FGR.