Fetal Medicine Foundation reference ranges for umbilical artery and middle cerebral artery pulsatility index and cerebroplacental ratio

Influence of birth weight on fetal cardiac indices at 35-37 weeks' gestation

OBJECTIVE

Echocardiographic studies have reported that fetuses with low birth weight, compared to those with normal birth weight, have globular hearts and reduced cardiac function. Dichotomizing continuous variables, such as birth weight, may be helpful in describing pathology in small studies but can prevent us from identifying physiological responses in relation to change in size. The aim of this study was to explore associations between fetal cardiac morphology and function and birth weight, as a continuous variable, as well as uterine artery (UtA) pulsatility index (PI), as an indirect measure of placental perfusion, and the cerebroplacental ratio (CPR), as an indirect measure of fetal oxygenation.

METHODS

This was a prospective study of 1498 women with singleton pregnancy undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. Pregnancies complicated by pregestational or gestational diabetes mellitus, chronic hypertension, pregnancy-induced hypertension or pre-eclampsia were excluded from the analysis. Conventional and more advanced echocardiographic modalities, such as speckle tracking, were used to assess fetal cardiac function in the right and left ventricles. The morphology of the fetal heart was assessed by calculating the right and left sphericity indices. In addition, the PI of the UtA, umbilical artery (UA) and fetal middle cerebral artery (MCA) was determined and the CPR was calculated by dividing MCA-PI by UA-PI. Multiple linear regression models were used to assess determinants of fetal echocardiographic parameters.

RESULTS

The study population included 146 (9.7%) small-for-gestational-age (SGA) fetuses with birth weight < 10^th percentile and 68 (4.5%) with fetal growth restriction (FGR). In the SGA and FGR groups, compared to the non-SGA and non-FGR fetuses, respectively, there was a more globular right ventricle and reduced left and right ventricular systolic function, and, from the left ventricular diastolic functional indices, the E/A ratio was increased. There was a linear association of right ventricular sphericity index, indices of left and right ventricular systolic function and E/A ratio with birth-weight Z-score. There were no significant associations between cardiac morphological and functional indices and UtA-PI Z-score or CPR Z-score.

CONCLUSIONS

This screening study at 35-37 weeks' gestation has demonstrated that birth weight is a determinant of fetal cardiac morphology and function but UtA-PI and CPR, as indirect measures of placental perfusion and fetal oxygenation, are not. This suggests that the differences in fetal cardiac indices between small and appropriately grown fetuses may be part of a normal physiological response to change in fetal size rather than part of a pathological adaptation to abnormal placental perfusion and fetal oxygenation. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Uncomplicated Monochorionic Twins: Two Normal Hearts Sharing One Placenta

Cardiovascular dysfunction has been reported in complicated monochorionic diamniotic (MCDA) pregnancies; however, little is known whether hemodynamic changes occur in uncomplicated MCDA twins. A prospective observational study was conducted including 100 uncomplicated MCDA twins matched by gestational age to 200 low-risk singletons. Echocardiography was performed at 26-30 weeks gestation and cord blood B-type natriuretic peptide (BNP) was measured at delivery. In both groups, z-scores for echocardiographic parameters were within normal ranges; however the monochorionic group had larger atrial areas (mean (standard deviation) right atria-to-heart ratio: 17.0 (2) vs. 15.9 (1); p = 0.018; left atria-to-heart ratio: 17.0 (3) vs. 15.8 (2); p < 0.001) and signs of concentric hypertrophy (right relative wall thickness: 0.66 (0.12) vs. 0.56 (0.11); p < 0.001; left relative wall thickness: 0.69 (0.14) vs. 0.58 (0.12); p < 0.001). Longitudinal function was increased in twins, leading to higher tricuspid annular plane systolic excursion (6.9 mm (0.9) vs. 5.9 mm (0.7); p < 0.001) and mitral annular plane systolic excursion (4.9 mm (0.8) vs. 4.4 mm (1.1); p < 0.001. BNP levels at birth were also higher in MCDA twins (median [interquartile range]: 20.81 pg/mL [16.69-34.01] vs. 13.14 pg/mL [9.17-19.84]; p < 0.001). Thus, uncomplicated MCDA fetuses have normal cardiac shape and function, but signs of cardiac adaptation were identified by echocardiographic and biochemical parameters, when compared with singletons.

Umbilical and Middle Cerebral Artery Doppler Measurements in Fetuses With Congenital Heart Block

OBJECTIVES

In fetal congenital complete heart block, the slow fetal heart rate prolongs the diastolic phase of the cardiac cycle, which may affect Doppler measurements that are typically used to quantify placental function. We here describe the umbilical artery (UA) and middle cerebral artery (MCA) Dopplers in a cohort of fetuses with heart block, hypothesizing that values will be increased but nevertheless remain associated with placental function and fetal outcome.

METHODS

We retrospectively reviewed Doppler measurements of the UA and MCA pulsatility index (PI) and resistance index in fetuses with complete heart block. The cerebroplacental ratio (CPR) was calculated as a marker of central redistribution. Measurements were transformed to Z scores and compared between fetuses born with a normal weight (appropriate for gestational age [AGA]) to those with fetal growth restriction (FGR) and correlated with a composite adverse outcome consisting of FGR, fetal death, or preterm birth prior to 34 weeks' gestation.

RESULTS

Fifty-four fetuses were included. There were 36 (67%) live births, 8 (22%) stillbirths, and 10 (19%) pregnancy terminations. Of those born alive, 14 (39%) had FGR. The UA PI decreased with gestational age and was higher in FGR compared with AGA fetuses (P < .001). Twenty-three percent of AGA fetuses developed absent end-diastolic flow in the UA. The MCA PI did not change with gestation and did not differ between AGA and FGR fetuses. The CPR was lower in FGR than in AGA fetuses (-2.43 ± 0.85 vs -1.44 ± 1.04, P = .006). The UA PI and resistance index were strongly correlated with the composite adverse outcome (P < .001).

CONCLUSIONS

The UA and MCA PI are significantly elevated in fetuses with complete heart block. The UA Doppler indices and CPR nevertheless still reflect placental function. Longitudinal measurements may be useful in monitoring well-being in fetuses with heart block.

S100B as a biomarker of brain injury in premature neonates. A prospective case - control longitudinal study

BACKGROUND

Neonatal brain injury (NBI) is a serious adverse outcome in premature neonates. We sought to determine the levels and prognostic value of serum S100B during the first three days of life in premature neonates (<34 weeks) that later developed NBI in the form of either intraventricular hemorrhage (IVH) or periventricular leukomalacia (PVL).

METHODS

This is a prospective case - control longitudinal study. Each case (n = 29) was matched according to birthweight and gestational age to one neonate with normal head ultrasound scans.

RESULTS

Neonates with NBI, had significantly higher S100B concentration during the first three days of life. In both groups S100B was significantly higher on the first day when compared to the next two days of life showing a downwards trend. Serum S100B on the first day was the best predictor for adverse neonatal outcome such as death or II-IV IVH grade. A cut-off value of 10.51 ng/ml serum S100B performed a sensitivity of 100% and a specificity of 93.9% to predict adverse neonatal outcome.

CONCLUSION

Further research on the predictive value of serum S100B regarding NBI in premature neonates is of great interest and may provide the first clinically useful biomarker for early detection of neonates at high risk.

Speckle-Tracking Echocardiography for the Assessment of Atrial Function during Fetal Life

INTRODUCTION

Speckle-tracking echocardiography has become a major tool in the evaluation of heart function. Atrial strain has emerged as an important component in the assessment of cardiac function, but there is a paucity of prenatal data. The aim of this study was to describe our initial experience of measurement of atrial strain in fetuses, with respect to both feasibility and the strain patterns observed.

METHODS

Four-chamber Digital Imaging and Communications in Medicine loops were acquired prospectively for deformation imaging. Fifty-three normal fetuses with no morphologic or functional abnormalities were selected for analysis. The three strain components of atrial cycle for both left atrium (LA) and right atrium (RA) were acquired-reservoir (LAres or RAres), conduit, and contraction (LAct or RAct)-and are expressed as a percentage. Ratios of these components were calculated. Simple linear regression was used to analyze how the dependent variables changed according to gestational age and frame rate.

RESULTS

The median gestational age was 30 weeks (range, 23-35), and the frame rate was 74 frames per second (fps; range, 35-121). Left atrial strain was feasible in 48/53 (91%), and right atrial strain in 46/53 (87%) of cases. The onset of LA contraction could be identified on the strain curves in 32 of 48 (67%) cases, and of the RA in 17 of 46 (37%) cases. The values of RAres and RAct were higher compared with those of LAres and LAct (33.9% vs 30.3%, P = .014; and 21.5% vs 16.8%, P = .005), and the contraction:reservoir ratio was also higher for RA (0.63 vs 0.55 for LA, P = .003). Higher values for LAres, LAct, RAres, and RAct were associated with higher frame rate (P = .007, .020, .049, and .012, respectively). The onset of LA contraction was better identified with a higher frame rate (mean 77 vs 59 fps when not seen, P = .007). A higher LA contraction:reservoir ratio was associated with a lower gestational age (P = .042).

CONCLUSION

Measurement of atrial strain is feasible in the fetal heart. The values are influenced by gestational age and frame rate, so it is necessary to account for these variables. Comparison of left versus right atrial strain values contrasts with those observed postnatally. Atrial function merits further study during fetal life, to aid understanding of maturational changes and disease states.

Investigation of the outcome of pregnancies complicated by increased fetal movements and their relation to underlying causes - A prospective cohort study

INTRODUCTION

Retrospective studies have reported an association between a single episode of significantly increased fetal movements (IFMs) and stillbirth after 28 weeks' gestation. This prospective study aimed to report the outcome of pregnancies associated with maternal perception of IFMs and determine whether this symptom is associated with adverse pregnancy outcome, a pathological intrauterine environment or placental dysfunction.

MATERIAL AND METHODS

Women reporting IFMs after 28 weeks' gestation were recruited from St Mary's Hospital, Manchester and Liverpool Women's Hospital, UK, between 1 November 2017 and 1 May 2019. Demographic and clinical information were obtained and an ultrasound scan was performed to assess fetal biometry, liquor volume and umbilical artery Doppler. Maternal serum samples were collected for analysis of placentally derived biomarkers using ELISA. After delivery, maternal and fetal outcome data were collected and placentas and umbilical cord blood were obtained for analysis using immunohistochemistry and ELISA, respectively. Placental and serum samples were matched by gestation and maternal characteristics to participants with normal fetal activity.

RESULTS

Seventy-seven women presented with IFM, representing 0.45% of the maternity population; 64 women consented to participate in the study, of which 7 (10.9%) experienced adverse pregnancy outcome: birthweight <3rd centile, 2 (3.1%); pH ≤7.10, 1 (1.6%); neonatal intensive care unit admission, 4 (6.3%). Women had IFM for varying lengths of time before presenting: 17.2% had IFM for less than 1 hour and 29.7% reported IFM lasting longer than 24 hours. Four women (6.3%) had abnormalities of the fetal heart rate trace on assessment. Women with IFM had similar modes of birth to women giving birth in participating maternity units. There was no evidence of macroscopic placental or umbilical cord abnormalities, alterations in microscopic placental structure, placental endocrine dysfunction or intrauterine hypoxia or infection in women with IFM compared with controls.

CONCLUSIONS

This prospective study did not find evidence of an association between IFM and adverse pregnancy outcome. It also did not find evidence of underlying placental dysfunction, cord anomalies, intrauterine hypoxia or infection in pregnancies with IFM. Further work is required to determine the strength of association between IFM and adverse pregnancy outcome and its origins. At present, IFM cannot be used to identify fetuses at increased risk of adverse outcome.

Clinical impact of Doppler reference charts on management of small-for-gestational-age fetuses: need for standardization

OBJECTIVE

To assess clinical variability in the management of small-for-gestational-age (SGA) fetuses according to different published Doppler reference charts for umbilical artery (UA) and fetal middle cerebral artery (MCA) Doppler indices and cerebroplacental ratio (CPR).

METHODS

We performed a systematic search of MEDLINE, EMBASE, CINAHL and the Web of Science databases from 1954 to 2018 for studies with the sole aim of creating fetal Doppler reference values for UA, MCA and CPR. The top cited articles for each Doppler parameter were included. Variability in Doppler values at the following clinically relevant cut-offs was assessed: UA-pulsatility index (PI) > 95^th percentile; MCA-PI < 5^th percentile; and CPR < 5^th percentile. Variability was calculated for each week of gestation and expressed as the percentage difference between the highest and lowest Doppler value at the clinically relevant cut-offs. Simulation analysis was performed in a cohort of SGA fetuses (n = 617) to evaluate the impact of this variability on clinical management.

RESULTS

From a total of 40 studies that met the inclusion criteria, 19 were analyzed (13 for UA-PI, 10 for MCA-PI and five for CPR). Wide discrepancies in reported Doppler reference values at clinically relevant cut-offs were found. MCA-PI showed the greatest variability, with differences of up to 51% in the 5^th percentile value at term. Variability in the 95^th percentile of UA-PI and the 5^th percentile of CPR at each gestational week ranged from 21% to 41% and 15% to 33%, respectively. As expected, on simulation analysis, these differences in Doppler cut-off values were associated with significant variation in the clinical management of SGA fetuses, despite using the same protocol.

CONCLUSIONS

The choice of Doppler reference chart can result in significant variation in the clinical management of SGA fetuses, which may lead to suboptimal outcomes and inaccurate research conclusions. Therefore, an attempt to standardize fetal Doppler reference ranges is needed. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Sex-specific reference ranges of cerebroplacental and umbilicocerebral ratios: longitudinal study

OBJECTIVES

Observational studies have shown that low cerebroplacental ratio (CPR) values predict an increased risk of adverse perinatal outcome. The inverse ratio, i.e. the umbilicocerebral ratio (UCR), has been suggested to be a better predictor as it rises with increasing degree of fetal compromise. However, longitudinal reference ranges for UCR have not been established, and whether gestational-age-dependent changes in CPR or UCR differ between male and female fetuses has not been studied. Thus, the aims of this study were to investigate sex-specific, gestational-age-associated serial changes in CPR and UCR during the second half of pregnancy and to establish longitudinal reference ranges.

METHODS

This was a secondary analysis of prospectively collected data from a dual-center longitudinal observational cohort study of low-risk singleton pregnancies. Doppler blood-flow velocity waveforms were obtained serially from the umbilical artery (UA) and fetal middle cerebral artery (MCA) from 19-41 weeks' gestation, and pulsatility indices (PIs) were determined. CPR and UCR were calculated as the ratios MCA-PI/UA-PI and UA-PI/MCA-PI, respectively. The course and outcome of pregnancies were recorded, and the sex of the fetus was determined after delivery. Reference intervals for CPR and UCR were constructed using multilevel modeling, and gestational-age-specific Z-scores in male and female fetuses were compared.

RESULTS

Of a total of 299 pregnancies enrolled, 284 (148 male and 136 female fetuses) were included in the final analysis, and 979 paired measurements of UA-PI and MCA-PI were used to construct sex-specific longitudinal reference intervals. The relationship of both CPR and UCR with gestational age was U-shaped, but in opposite directions. There was a small but significant difference in Z-scores of CPR and UCR between male and female fetuses throughout the second half of pregnancy (P = 0.007).

CONCLUSIONS

We have established longitudinal reference ranges for CPR and UCR suitable for serial monitoring, with the possibility of refining assessment by using fetal sex-specific ranges and conditioning by a previous measurement. The clinical significance of such refinements needs further evaluation. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Normative references and clinical correlates of fetal umbilical artery Doppler indices in southwestern Nigeria

OBJECTIVE

To derive normative references for umbilical artery (UA) Doppler indices, including pulsatility index (PI), resistance index (RI), and systolic/diastolic (SD) ratio, for singleton pregnancies in Ile-Ife, Nigeria, and compare them with reference values from other populations.

METHODS

A longitudinal study involving 415 women with a singleton fetus at 26-40 gestational weeks attending Obafemi Awolowo University Hospital, Ile-Ife, between July 2015 and March 2019. Fetal UA PI, RI, and SD ratio were measured every 4 weeks until delivery. Reference values from the 2.5th to the 97.5th centiles were derived from 1375 measurements. Correlations between indices and bio-demographic characteristics were assessed; regression equations were generated.

RESULTS

The RI, PI, and SD ratio decreased by 0.013, 0.027, and 0.71, respectively, for each additional week of pregnancy. There was a negative correlation between the three indices and birthweight (P<0.001), but not maternal parity, age, or fetal gender. Regression equations for RI, PI, and SD ratio were, respectively, 1.004 - 0.013x, 1.78 - 0.027x, and 4.77 - 0.71x, where x is gestational age (weeks).

CONCLUSION

The derived normative references for fetal UA Doppler indices are recommended for monitoring high-risk pregnancies in Nigeria. The indices are comparable to those derived from Norwegian, Thai, and British cohorts.

Apparent diffusion coefficient of different areas of brain in foetuses with intrauterine growth restriction

Purpose

This study aimed to compare the apparent diffusion coefficient (ADC) values of different brain areas between two groups of intrauterine growth restricted (IUGR) foetuses and control cases.

Material and methods

A total of 38 foetuses with IUGR and 18 normal control foetuses with similar gestational age were compared using a 3T magnetic resonance scanner. IUGR cases included 23 foetuses with clinical severity signs (group A) and 15 foetuses without clinical severity signs (group B). ADC values were measured in different brain regions and compared among groups. Foetuses with structural brain abnormalities were excluded from the study.

Results

All foetuses had normal foetal structural brain anatomy. Head circumference (HC) < 5% was more common in IUGR group A compared to IUGR group B (56.5% vs. 13.3%, p < 0.0001). In comparison to the normal group, the ADC values in IUGR foetuses were significantly lower in cerebellar hemispheres (CH) (1.239 vs. 1.280.5 × 10^-3 mm²/s, p = 0.045), thalami (1.205 vs. 1.285 × 10^-3 mm²/s, p = 0.031) and caudate nucleus (CN) (1.319 vs. 1.394 × 10^-3 mm²/s, p = 0.04). However, there were no significant differences in ADC values between IUGR subtypes. Among all brain regions, pons had the lowest ADC values.

Conclusions

ADC values of thalami, CN, and CH were significantly lower in IUGR than control foetuses, while there was no significant difference among IUGR groups. Further studies are needed to evaluate the prognostic value of ADC changes in IUGR foetuses.

Volume blood flow-based indices of fetal brain sparing in the second half of pregnancy: A longitudinal study

INTRODUCTION

Cerebroplacental ratio (CPR) and umbilicocerebral ratio (UCR) are clinically used as a measure of fetal brain sparing. These are calculated as the ratios between the pulsatility indices (PIs) of middle cerebral (MCA) and umbilical (UA) arteries, and are an indirect representation of the balance between cerebral and placental perfusion. Volume blood flow (Q)-based ratios, ie Q-CPR or Q-UCR, would directly reflect the distribution of fetal cardiac output to the placenta and brain. Thus, we aimed to determine the development pattern of Q-CPR and Q-UCR during the second half of pregnancy, construct reference intervals, and evaluate their association with CPR and UCR.

MATERIAL AND METHODS

In a longitudinal cohort study of low-risk pregnancies, the inner diameter of the fetal superior vena cava (SVC) and umbilical vein (UV) was measured and velocity waveforms were obtained from the MCA, UA, UV and SVC using ultrasound at approximately 4-weekly intervals from 20 to 41 weeks. The CPR was calculated as PI_MCA /PI_UA and the inverse ratio was the UCR. Cerebral and placental blood flows were estimated as the product of mean velocity and cross-sectional area of the SVC and UV, respectively. Q-CPR was calculated as Q_SVC /Q_UV and the inverse as the Q-UCR. Gestational age-specific reference intervals were calculated and associations between variables were tested using multilevel regression modeling.

RESULTS

Longitudinal reference intervals of Q-CPR and Q-UCR were established based on 471 paired measurements of Q_SVC and Q_UV obtained serially from 134 singleton pregnancies. The mean Q-CPR increased from 0.4 to 0.8 during the second half of pregnancy and Q-UCR declined from 2.5 to 1.3, while the CPR and UCR had U-shaped curves but in opposite directions. No significant correlation was found between CPR and Q-CPR (R = 0.10; P = .051), or UCR and Q-UCR (R = 0.09; P = .11), and the agreement between PI-based and Q-based indices of fetal brain sparing was poor.

CONCLUSIONS

Indices of fetal brain sparing based on placental and cerebral volume blood flow differ from those calculated from UA and MCA PIs. They correlated poorly with conventional CPR and UCR, indicating that they may provide additional/different physiological information. Reference values of Q-CPR and Q-UCR established here can be useful to investigate their clinical value further.

Prescriptive Reference Standards of Third-Trimester Cerebroplacental Ratio and Its Physiological Determinants

OBJECTIVE

To construct valid reference standards reflecting optimal cerebroplacental ratio and to explore its physiological determinants.

METHODS

A cohort of 391 low-risk pregnancies of singleton pregnancies of nonmalformed fetuses without maternal medical conditions and with normal perinatal outcomes was created. Doppler measurements of the middle cerebral artery and umbilical artery were performed at 24-42 weeks. Reference standards were produced, and the influence of physiological determinants was explored by nonparametric quantile regression. The derived standards were validated in a cohort of 200 low-risk pregnancies.

RESULTS

Maternal body mass index was significantly associated with the 5th centile of the cerebroplacental ratio. For each additional unit of body mass index, the 5th centile was on average 0.014 lower. The derived 5th, 10th, and 50th centiles selected in the validation cohort were 5, 9.5, and 51% of the measurements.

CONCLUSIONS

This study provides methodologically sound prescriptive standards and suggests that maternal body mass index is a determinant of a cutoff commonly used for decision-making.

Cerebroplacental ratio (CPR) and reduced fetal movement: predicting neonatal outcomes

Objective: The aim of this study was to evaluate the role of cerebroplacental ratio (CPR) in term pregnancies with reduced fetal movements (RFM) and appropriate for gestational age (AGA)fetuses to predict poor neonatal outcomes.Methods: A prospective cohort study was performed on 150 singleton pregnancies with gestational age of 37-41 weeks and multiple episodes of RFM (case group) and 150 pregnancies within the same criteria only without RFM (control group). Both groups had appropriate for gestational age (AGA)fetuses. Umbilical artery (UA) and middle cerebral artery (MCA) pulsatility indices (PI) were measured, and MCA to UA ratio (CPR) was calculated. Doppler indices and neonatal outcomes were compared between the two groups. Independent prediction role of CPR MoM was evaluated through a binary logistic regression method.Results: The RFM group had significantly higher UA- PI MoM (1.01 ± 0.19 versus 0.86 ± 0.05, p < .001), lower MCA MoM (1.28 ± 0.20 versus 1.40 ± 0.13, (p < .001)) and lower CPR MoM (0.98 ± 0.24 versus 1.23 ± 0.12, (p < .001)) compared to the control group. Mean umbilical artery pH was lower in the RFM group and the frequency of neonatal UA cord pH <7.2 was higher in the RFM group. In RFM group, CPR MoM showed a significant linear correlation with birth weight centiles (r = 0.244, p = .003), umbilical artery pH (r = 0.319, p < .001) and Apgar score at minute 1 (r = 0.332, p < .001). CPR MoM exhibited negative correlation with duration of NICU stay (r= -0.187, p = .022). No similar correlation was observed in the control group. In binary logistic regression analysis, CPR MoM was adjusted for the results of NST; and it was concluded that CPR MoM was the only significant predictor of Apgar score minute 1 = <7 (OR: 0.004; 95% CI: 0.0002-0.0673, p < .001), umbilical artery ph <7.2 (OR: 0.019; 95% CI: 0.00005-0.0423, p < .001) and NICU admission (OR: 0.116; 95% CI: 0.018-0.744, p = .023). In multivariate binary logistic regression analysis included parity, history of abortion and ART, AFI, BPP and CPR MoM; the AFI (OR: 0.976; 95% CI: 0.957-0.995, p = .014), BPP (OR: 0.306; 95% CI: 0.172-0.545, p < .001) and CPR MoM (OR: 0.00005 95% CI: 0.000003-0.00061, p < .001) were the significant predictor of RFM. Area under the curve in receiver operating characteristics (ROC) curve was calculated as 0.828 for CPR MoM as a predictor of RFM (SE: 0.024, p < .001), yielding sensitivity and specificity estimates of 80.0% and 65.0%, respectively, using an optimal cutoff level of = < 1.19.Conclusion: This study concluded that reduced fetal movement was significantly related to low CPR MOM. Also, it showed the independent role of CPR MoM for prediction of lower neonatal umbilical artery pH, lower Apgar score minute 1 and higher rate of NICU admission in AGA term fetuses without considering NST results. Also, AFI, BPP and CPR MoM are significant predictors of RFM.

Fetal Middle Cerebral Artery Pulsatility Index in No-Risk Pregnancies: Effects of Auditory Stimulation and Pregnancy Order

Pulsatility index (PI) values in a fetal middle cerebral artery (MCA) were compared in no-risk pregnancies to examine the differences related to auditory stimulation test and pregnancy order. The study included 196 women with no-risk pregnancies selected from the database of more than 1000 pregnant women divided into two groups. Group 1 consisted of 98 nulliparous women (C1 = 98) and Group 2 consisted of 98 parous women (C2 = 98). All pregnant women were of comparable age and fetal gestational age (GA) when MCA-PI values were recorded. Measurements of PI values in fetal MCA were obtained before and immediately after the application of fetal auditory stimulation test. The MCA-PI measuring was conducted in the period between the 36th and the 41st week of GA. The results showed that PI baseline values and PI values after defined auditory stimulation were significantly different when measured in nulliparous women compared to parous women (p = 0.001; p = 0.003, respectively), while no group differences were observed in relative PI value changes due to auditory stimulation. These findings suggest that hemodynamic changes in fetal MCA caused by defined auditory stimulation measured by PI value changes may be valuable in the assessment of fetal auditory perception functionality and its development.

Fetal acute cerebral vasoreactivity to maternal hyperoxia in low-risk pregnancies: a cross-sectional study

OBJECTIVE

To establish whether fetal cerebral vasoreactivity (CVR_O2 ), following maternal hyperoxia, is predicted by fetal cerebral and uteroplacental Doppler pulsatility indices (PI) at baseline, fetal pulmonary vasoreactivity to oxygen (PVR_O2 ), gestational age (GA), or sex.

METHODS

Pulsatility index of middle (MCA), anterior (ACA), posterior cerebral (PCA), umbilical (UA), uterine (UtA), and branch of the pulmonary arteries (PA) were obtained, by ultrasound, before (baseline), during (hyperoxia) and after 15 minutes of maternal administration of 8 L/min of 100% oxygen, through a non-rebreathing face mask, in normal singleton pregnancies within 20 to 38 weeks' gestation. CVR_O2 was defined as changes greater than zero in z score of PI of the cerebral arteries from baseline to hyperoxia. Logistic modeling was applied to identify CVR_O2 predictors.

RESULTS

A total of 97 pregnancies were eligible. In the overall population, median z scores of PI of MCA, ACA, and PCA did not differ between study phases. Based on the logistic model, baseline z scores for cerebral PI and GA were the best predictors of CVR_O2 .

CONCLUSIONS

In low-risk pregnancies, fetal CVR_O2 to hyperoxia does not occur uniformly but depends on cerebral PI and GA at baseline. These findings may provide useful reference points when oxygen is administered in high-risk pregnancies.

Association of Maternal and Umbilical Cord Blood Lipid Parameters with Uterine and Fetal-Placental Blood Flow in Hypertensive and Normotensive Pregnancies

Purpose

There is a growing evidence suggesting that hypertensive disorders of pregnancy (HDP), especially preeclampsia, are associated with an increased risk of cardiometabolic disease for both mother and child later in life. The objective of this study was to determine the association of maternal and umbilical cord blood (UCB) lipid profiles with uterine and fetal-placental blood flow at the third trimester of pregnancy.

Patients and Methods

A total of 1,135 women were prospectively followed through pregnancy and data for 812 mother-newborn pairs, including 170 HDP ‎developed subjects and ‎642 ‎normotensive subjects were analyzed at the end of the study. Maternal serum and UCB triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and non-HDL-C levels were compared between HDP and normotensive groups; moreover, the association between lipid parameters and abnormal pulsatility indices (PIs) of uterine (UtA), umbilical (UA), and middle cerebral (MCA) arteries was evaluated with multivariate regression analysis models. The same analyses were carried out on subgroups of HDP (preeclampsia vs gestational hypertension).

Results

The mean TG, TC, LDL-C, and non-HDL-C levels were significantly higher in mother-newborn pairs of the HDP group compared to the normotensive group. In the HDP group, maternal TG and non-HDL-C levels were shown to have a significant association with abnormal UtA-PI (p<0.001 and p=0.039, respectively). We also found a positive significant association of fetal hypertriglyceridemia with abnormal UA-PI and MCA-PI in the HDP group (p=0.042 and p=0.021, respectively). However, no such associations were observed in normotensive mother-newborn pairs. Similar trends were observed in preeclamptic subjects after subgroup analysis.

Conclusion

Maternal TG and non-HDL-C levels as well as fetal TG level are significantly associated with disturbed uterine and fetal-placental blood flow in HDP.

Longitudinal Doppler references for monochorionic twins and comparison with singletons

OBJECTIVES

To construct monochorionic (MC) twin-specific longitudinal Doppler references for umbilical artery pulsatility index (UA-PI), middle cerebral artery (MCA) PI and peak systolic velocity (PSV) and ductus venosus (DV) PI derived from a strictly selected cohort of uncomplicated MC twins. The secondary aim of the study was to compare our findings with singleton reference charts.

METHODS

A retrospective evaluation was made of all consecutive uncomplicated MC twin pregnancies referred to our Unit from 2010 to 2018. Fortnightly serial examinations were performed of UA-PI, MCA-PI, MCA-PSV and DV-PI, according with the clinical protocol, from 20 to 37 weeks of gestation. We included cases with at least four ultrasound examinations, delivery at our hospital and complete neonatal follow up. A two-step method was used to trace the estimated centile curves: estimation of the median was performed with appropriate fractional polynomials by a multilevel model and estimation of the external centiles through the residuals (quantile regression). The comparison with singletons was made by plotting the references derived from the present study on the referred charts commonly used for singletons.

RESULTS

The study group comprised 150 uncomplicated MC twin pairs. Estimated centiles (3rd, 5th, 10th, 50th, 90th, 95th, 97th) of UA-PI, MCA-PI, MCA-PSV and DV-PI in function of the gestational age are presented. The comparison with singletons showed substantial differences, with higher UA-PI and lower MCA-PI and PSV median values in MC twins. Median DV PI values were similar to the values for singletons, while the upper centiles were higher in MC twins.

CONCLUSIONS

This study sets out MC twin-specific longitudinal references for UA-PI, MCA-PI, MCA-PSV and DV-PI derived from the largest series of uncomplicated MC twin pregnancies presently available. The comparison with singleton reference values underscores the deviation from physiology that is intrinsic to these unique pregnancies and supports the need for MC twin-specific charts.

Prediction of adverse perinatal outcome by serum placental growth factor and soluble fms-like tyrosine kinase-1 in women undergoing induction of labor

OBJECTIVE

To investigate the additive value of serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1), measured within 24 h prior to induction of labor, to the performance of screening for adverse perinatal outcome provided by maternal risk factors and the cerebroplacental ratio (CPR).

METHODS

This was a prospective observational study of 795 singleton pregnancies undergoing induction of labor at ≥ 37 weeks' gestation. Before induction of labor, Doppler ultrasound was used to measure the pulsatility index (PI) in the umbilical artery (UA) and fetal middle cerebral artery (MCA) and maternal blood was obtained for measurement of serum PlGF and sFlt-1. The measured UA-PI, MCA-PI and their ratio (CPR) were converted to multiples of the median (MoM) after adjustment for gestational age, and the measured PlGF and sFlt-1 were converted to MoM after adjustment for gestational age, maternal characteristics and the machine used for the assays. Univariable and multivariable logistic regression analysis was used to determine factors that provided a significant contribution in the prediction of adverse perinatal outcome, defined as the presence of any one of Cesarean section for non-reassuring fetal status in labor, umbilical arterial or venous cord blood pH ≤ 7 and ≤ 7.1, respectively, 5-min Apgar score < 7 or admission to the neonatal intensive care unit for ≥ 24 h. The detection rate (DR) and false-positive rate (FPR) in screening for adverse perinatal outcome were determined.

RESULTS

In pregnancies with adverse perinatal outcome, compared to those without, median serum PlGF MoM was lower (0.44; interquartile range (IQR), 0.30-0.82 vs 0.60; IQR, 0.36-1.07; P = 0.003), but median sFlt-1 MoM was not significantly different (P = 0.080). Multivariable regression analysis demonstrated that, in the prediction of adverse perinatal outcome, there was significant contribution from maternal risk factors and CPR MoM but not PlGF MoM or sFlt-1 MoM. The performance of screening for adverse perinatal outcome achieved by maternal risk factors alone (DR of 28.9% at FPR of 10%) was not improved by the addition of CPR (DR of 33.8% at FPR of 10%) (area under the curve, 0.702; 95% CI, 0.654-0.750 vs 0.712; 95% CI, 0.664-0.760; P = 0.233).

CONCLUSION

Serum PlGF and sFlt-1, measured within 24 h prior to induction of labor, do not provide a significant additional contribution to maternal risk factors in the prediction of adverse perinatal outcome. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Third-trimester Reference Ranges for Cerebroplacental Ratio and Pulsatility Index for Middle Cerebral Artery and Umbilical Artery in Normal-growth Singleton Fetuses in the Israeli Population

BACKGROUND

The ratio between the fetal umbilical artery pulsatility index (UA-PI) and the middle cerebral artery pulsatility index (MCA-PI) is termed the cerebroplacental ratio (CPR). The CPR represents fetal blood flow redistribution at the early stages of placental insufficiency; moreover, it has predictive value for adverse intrapartum and neonatal outcomes. However, internationally accepted reference ranges for CPR are lacking.

OBJECTIVE

This study sought to establish UA-PI, MCA-PI, and CPR reference ranges in low-risk, normal-growth singleton fetuses during the third trimester of pregnancy.

METHODS

A retrospective cohort cross-sectional study was performed in the obstetrics ultrasound unit of a university hospital in Israel. We reviewed all fetal and maternal electronic records of pregnant women referred for ultrasound assessment during the third trimester between January 2014 and January 2019. We included only singleton pregnancies with normal anatomy scans and a normal third-trimester estimated fetal weight. The UA-PI, MCA-PI, and CPR reference ranges were reconstructed for each of the vessels for each gestational age between 29 and 41 weeks.

RESULTS

A total of 560 pregnancies met the inclusion criteria. Satisfactory waveforms and measurements were obtained in all cases. At least 18 women enrolled at each gestational week. The MCA-PI and CPR values showed a similar parabolic curve during the third trimester of pregnancy, with a peak value at 32 and 33 gestational weeks, respectively. The UA-PI showed a linear and gradual decrease over the gestational age.

CONCLUSIONS

In this study we established UA-PI, MCA-PI, and CPR reference ranges in low-risk, normal-growth singleton fetuses during the third trimester based on the Israeli population.

Two-stage approach for prediction of small-for-gestational-age neonate and adverse perinatal outcome by routine ultrasound examination at 35-37 weeks' gestation

BACKGROUND

Justification of prenatal screening for small-for-gestational-age (SGA) fetuses near term is based on, first, evidence that such fetuses/neonates are at increased risk of stillbirth and adverse perinatal outcome, and, second, the expectation that these risks can be reduced by medical interventions, such as early delivery. However, there are no randomized studies demonstrating that routine screening for SGA fetuses and appropriate interventions in the high-risk group can reduce adverse perinatal outcome. Before such meaningful studies can be undertaken, it is essential that the best approach for effective identification of SGA neonates is determined, and that the contribution of SGA neonates to the overall rate of adverse perinatal outcome is established. In a previous study of pregnancies undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation, we found that, first, screening by estimated fetal weight (EFW) < 10^th percentile provided poor prediction of SGA neonates and, second, prediction of > 85% of SGA neonates requires use of EFW < 40^th percentile.

OBJECTIVES

To examine the contribution of SGA fetuses to the overall rate of adverse perinatal outcome and, to propose a two-stage approach for prediction of a SGA neonate at routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation.

METHODS

This was a prospective study of 45 847 singleton pregnancies undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. First, we examined the relationship between birth-weight percentile and adverse perinatal outcome, defined as stillbirth, neonatal death or admission to the neonatal unit for ≥ 48 h. Second, we used a two-stage approach for prediction of a SGA neonate and adverse perinatal outcome; in the first stage, fetal biometry was used to distinguish between pregnancies at very low risk (EFW ≥ 40^th percentile) and those at increased risk (EFW < 40^th percentile) and, in the second stage, the pregnancies with EFW < 40^th percentile were stratified into high-, intermediate- and low-risk groups based on the results of EFW and pulsatility index in the uterine arteries, umbilical artery and fetal middle cerebral artery. Different percentiles of EFW and Doppler indices were used to define each risk category, and the performance of screening for a SGA neonate and adverse perinatal outcome in pregnancies delivered at ≤ 2, 2.1-4 and > 4 weeks after assessment was determined. We propose that the high-risk group would require monitoring from initial assessment to delivery, the intermediate-risk group would require monitoring from 2 weeks after initial assessment to delivery, the low-risk group would require monitoring from 4 weeks after initial assessment to delivery, and the very low-risk group would not require any further reassessment.

RESULTS

First, although in neonates with low birth weight (< 10^th percentile) the risk of adverse perinatal outcome is increased, 84% of adverse perinatal events occur in the group with birth weight ≥ 10^th percentile. Second, in screening by EFW < 10^th percentile, the predictive performance for a SGA neonate is modest for those born at ≤ 2 weeks after assessment (83% and 69% for neonates with birth weight < 3^rd and < 10^th percentiles, respectively), but poor for those born at 2.1-4 weeks (65% and 45%, respectively) and > 4 weeks (40% and 30%, respectively) after assessment. Third, improved performance of screening, especially for those delivered at > 2 weeks after assessment, is potentially achieved by a proposed new approach for stratifying pregnancies into management groups based on findings of EFW and Doppler indices (prediction of birth weight < 3^rd and < 10^th percentiles for deliveries at ≤ 2, 2.1-4 and > 4 weeks after assessment: 89% and 75%, 83% and 74%, and 88% and 82%, respectively). Fourth, the predictive performance for adverse perinatal outcome of EFW < 10^th percentile is very poor (26%, 9% and 5% for deliveries at ≤ 2, 2.1-4 and > 4 weeks after assessment, respectively) and this is improved by the proposed new approach (31%, 22% and 29%, respectively).

CONCLUSIONS

This study presents an approach for stratifying pregnancies undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation into four management groups based on findings of EFW and Doppler indices. This approach potentially has a higher predictive performance for a SGA neonate and adverse perinatal outcome than that of screening by EFW < 10^th percentile. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Routine assessment of cerebroplacental ratio at 35-37 weeks' gestation in the prediction of adverse perinatal outcome

BACKGROUND

Third-trimester studies in selected high-risk pregnancies have reported that low cerebroplacental ratio, due to high pulsatility index in the umbilical artery, and or decreased pulsatility index in the fetal middle cerebral artery, is associated with increased risk of adverse perinatal outcomes.

OBJECTIVE

To investigate the predictive performance of screening for adverse perinatal outcome by the cerebroplacental ratio measured routinely at 35-37 weeks' gestation.

STUDY DESIGN

This was a prospective observational study in 47,211 women with singleton pregnancies undergoing routine ultrasound examination at 35⁺⁶ to 37⁺⁶ weeks' gestation, including measurement of umbilical artery-pulsatility index and middle cerebral artery-pulsatility index. The measured umbilical artery-pulsatility index and middle cerebral artery-pulsatility index and their ratio were converted to multiples of the median after adjustment for gestational age. Multivariable logistic regression analysis was used to determine whether umbilical artery-pulsatility index, middle cerebral artery-pulsatility index, and cerebroplacental ratio improved the prediction of adverse perinatal outcome that was provided by maternal characteristics, medical history, and obstetric factors. The following outcome measures were considered: (1) adverse perinatal outcome consisting of stillbirth, neonatal death, or hypoxic-ischemic encephalopathy grades 2 and 3; (2) presence of surrogate markers of perinatal hypoxia consisting of umbilical arterial or venous cord blood pH ≤7 and ≤7.1, respectively, 5-minute Apgar score <7, or admission to the neonatal intensive care unit for >24 hours; (3) cesarean delivery for presumed fetal compromise in labor; and (4) neonatal birthweight less than the third percentile for gestational age.

RESULTS

First, the incidence of adverse perinatal outcome, presence of surrogate markers of perinatal hypoxia, and cesarean delivery for presumed fetal compromise in labor was greater in pregnancies with small for gestational age neonates with birthweight <10th percentile compared with appropriate for gestational age neonates; however, 80%-85% of these adverse events occurred in the appropriate for gestational age group. Second, low cerebroplacental ratio <10th percentile was associated with increased risk of adverse perinatal outcome, presence of surrogate markers of perinatal hypoxia, cesarean delivery for presumed fetal compromise in labor, and birth of neonates with birthweight less than third percentile. However, multivariable regression analysis demonstrated that the prediction of these adverse outcomes by maternal demographic characteristics and medical history was only marginally improved by the addition of cerebroplacental ratio. Third, the performance of low cerebroplacental ratio in the prediction of each adverse outcome was poor, with detection rates of 13%-26% and a false-positive rate of about 10%. Fourth, the detection rates of adverse outcomes were greater in small for gestational age than in appropriate for gestational age babies and in pregnancies delivering within 2 weeks rather than at any stage after assessment; however, such increase in detection rates was accompanied by an increase in the false-positive rate. Fifth, in appropriate for gestational age neonates, the predictive accuracy of cerebroplacental ratio was low, with positive and negative likelihood ratios ranging from 1.21 to 1.82, and 0.92 to 0.98, respectively; although the accuracy was better in small for gestational age neonates, this was also low with positive likelihood ratios of 1.31-2.26 and negative likelihood ratios of 0.69-0.92. Similar values were obtained in fetuses classified as small for gestational age and appropriate for gestational age according to the estimated fetal weight.

CONCLUSIONS

In pregnancies undergoing routine antenatal assessment at 35-37 weeks' gestation, measurement of cerebroplacental ratio provides poor prediction of adverse perinatal outcome in both small for gestational age and appropriate for gestational age fetuses.

Reference Centile Chart of Fetal Cerebroplacental Doppler from 24 to 40 Weeks Gestation in Indian Population

Objective

Construction of reference centile chart of middle cerebral (MCA) and umbilical artery (UA) Doppler along with cerebroplacental ratio from 24 to 40 weeks gestation in Indian population.

Method

It was a cross-sectional observational study; antenatal women between 24 and 40 weeks gestation underwent the MCA and UA Doppler. The centile charts for MCA, UA and cerebroplacental ratio (CPR) were derived.

Results

Total 300 antenatal women were included; the MCA PI, RI, S/D ratio values showed a parabolic curve with the peak at 33-35 weeks; the umbilical artery Doppler and cerebroplacental ratio showed a linear decrease with increasing gestational age. The regression analysis showed a weak correlation between the Doppler parameters and the gestational age. The MOM values of all Doppler parameters, across the gestational age, were also derived.

Conclusion

The constructed MCA, UA and CPR charts along with their MOM values could be used as reference for the regional population.

Prediction of adverse perinatal outcome by cerebroplacental ratio in women undergoing induction of labor

OBJECTIVE

To investigate the performance of screening for adverse perinatal outcome by the cerebroplacental ratio (CPR) measured within 24 h prior to induction of labor.

METHODS

This was a prospective observational study of 1902 singleton pregnancies undergoing induction of labor at ≥ 37 weeks' gestation. Doppler ultrasound was used to measure the pulsatility index (PI) in the umbilical artery (UA) and fetal middle cerebral artery (MCA) within 24 h before induction of labor. The measured UA-PI and MCA-PI and their ratio were converted to multiples of the median after adjustment for gestational age. Univariable and multivariable logistic regression analysis was used to determine whether CPR improved the prediction of adverse perinatal outcome provided by maternal characteristics, medical history and obstetric factors. The detection rate (DR) and false-positive rate (FPR) of screening by CPR were estimated for Cesarean section for presumed fetal distress and adverse neonatal outcome, which included umbilical arterial or venous cord blood pH ≤ 7 and ≤ 7.1, respectively, 5-min Apgar score < 7, admission to the neonatal intensive care unit for > 24 h or hypoxic ischemic encephalopathy.

RESULTS

A combination of maternal and pregnancy characteristics, including age, weight, racial origin, previous obstetric history, pre-eclampsia, gestational age at delivery and amniotic fluid volume, identified 39% of pregnancies requiring Cesarean section for fetal distress at a FPR of 10%; addition of CPR did not improve the performance of screening. In screening for adverse neonatal outcome by a combination of parity and CPR, the DR was 17% at a FPR of 10%.

CONCLUSION

Low CPR, measured within 24 h prior to induction of labor, is associated with increased risk of Cesarean section for fetal distress and adverse neonatal outcome, but the performance of CPR for such surrogate measures of fetal hypoxic morbidity is poor. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Arterial flow patterns in healthy transitioning near-term neonates

OBJECTIVE

Significant haemodynamic changes occur at delivery impacting organ blood flow distribution. We aimed to characterise Doppler indices patterns over time in three different organs (brain, gut and kidney) and test them as measures of vascular resistance.

DESIGN

Observational cohort study. Serial Doppler interrogations of the anterior cerebral, superior mesenteric and renal arteries within 2 hours, 2-6, and 24 hours of life, in combination with central haemodynamic data.

PATIENTS

Healthy, near-term (>36 weeks of gestation) neonates.

OUTCOME MEASURES

Pulsatility (PI) and Resistance Indices (RI) patterns and organ-specific conductances, detailed echocardiographic haemodynamic measures.

RESULTS

Twenty-one babies were studied. Doppler morphology and adaptation patterns were distinctly different between the organs (brain, gut and kidney) supporting autonomous vascular regulatory effects. The PI differentiated especially between kidney and other organ flow consistently over time. PI and RI for all three organs decreased. The variance in organ conductance did not explain the variance in 1/PI, indicating that PI is not a measure of resistance. Superior mesenteric artery had the highest velocity with 72 cm/s. Non-invasively acquired pilot serial values in a normal population are given. Patent ductus arteriosus flow remained open at discharge for 36%.

CONCLUSIONS

Haemodynamic transitioning patterns assessed by serial Dopplers in healthy near-term neonates differ in brain, gut and kidney: Doppler waveform morphology differs, and PI differentiates renal Doppler morphology, compared with the other organs. While PI and RI decline for all organs, they do not measure resistance. Brain artery velocity increases, mesenteric perfusion is variable and renal Vmax decreases.