Comparison of different methods of screening for preterm pre-eclampsia: cohort study

OBJECTIVE

To compare the predictive performance for pre-eclampsia (PE) of three different first-trimester mathematical models of screening, which combine maternal risk factors with mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF), and two risk scoring systems, based on NICE and ACOG recommendations.

METHODS

This was a prospective cohort study performed in eight fetal-medicine units in five different regions of Spain between September 2017 and December 2019. All pregnant women with singleton pregnancies and non-malformed live fetuses attending their routine ultrasound examination at 11+0 to 13+6 weeks' gestation were invited to participate in the study. Maternal characteristics and medical history were recorded and measurements of MAP, UtA-PI, serum PlGF and pregnancy associated plasma protein-A (PAPP-A) were converted into multiples of the median (MoM). Risks for term, preterm-PE (< 37 weeks' gestation) and early-PE (< 34 weeks' gestation) were calculated according to the FMF competing risks model, the Crovetto et al., logistic regression model, and Serra et al., Gaussian model. Patient classification based on NICE and ACOG guidelines was also performed. We estimated detection rates (DR) with their 95% confidence intervals (CIs) at a fixed 10% screen positive rate (SPR), as well as the area under the receiver operating characteristic curve (AUROC) for preterm-PE, early-PE, and all PE for the three mathematical models. For the scoring systems, we calculated DR and SPR. Risk calibration was also assessed.

RESULTS

The study population comprised of 10,110 singleton pregnancies, including 32 (0.3%) that developed early-PE, 72 (0.7%) that developed preterm-PE and 230 (2.3%) of any PE. At fixed 10% SPR, the FMF, Crovetto et al., and Serra et al., detected 82.7% (95% CI, 69.6 to 95.8%), 73.8% (95% CI, 58.7 to 88.9%), and 79.8% (95% CI, 66.1 to 93.5%) of early-PE; 72.7% (95% CI, 62.9 to 82.6%), 69.2% (95% CI, 58.8 to 79.6%), and 74.1% (95% CI, 64.2 to 83.9%) of preterm-PE and 55.1% (95% CI, 48.8 to 61.4%), 47.1% (95% CI, 40.6 to 53.5%), and 53.9% (95% CI, 47.4 to 60.4%) of all PE, respectively. The best correlation between predicted and observed cases was achieved by the FMF model, with an AUROC of 0.911 (95% CI, 0.879 to 0.943), a slope of 0.983 (95% CI, 0.846-1.120) and an intercept of 0.154 (95% CI, -0.091 to 0.397). The NICE criteria identified 46.7% (95% CI, 35.3 to 58.0%) of preterm-PE at 11% SPR and ACOG criteria identified 65.9% (95% CI, 55.4 to 76.4%) of preterm-PE at 33.8% SPR.

CONCLUSIONS

The best performance of screening for preterm-PE is achieved by mathematical models that combine maternal factors with MAP, UtA-PI and PlGF, as compared to risk-scoring systems like NICE or ACOG criteria. While all three algorithms show similar results in terms of overall prediction, the FMF model showed the best performance at the individual level. This article is protected by copyright. All rights reserved.

Validation of machine-learning model for first-trimester prediction of pre-eclampsia using cohort from PREVAL study

OBJECTIVE

Effective first-trimester screening for pre-eclampsia (PE) can be achieved using a competing-risks model that combines risk factors from the maternal history with multiples of the median (MoM) values of biomarkers. A new model using artificial intelligence through machine-learning methods has been shown to achieve similar screening performance without the need for conversion of raw data of biomarkers into MoM. This study aimed to investigate whether this model can be used across populations without specific adaptations.

METHODS

Previously, a machine-learning model derived with the use of a fully connected neural network for first-trimester prediction of early (< 34 weeks), preterm (< 37 weeks) and all PE was developed and tested in a cohort of pregnant women in the UK. The model was based on maternal risk factors and mean arterial blood pressure (MAP), uterine artery pulsatility index (UtA-PI), placental growth factor (PlGF) and pregnancy-associated plasma protein-A (PAPP-A). In this study, the model was applied to a dataset of 10 110 singleton pregnancies examined in Spain who participated in the first-trimester PE validation (PREVAL) study, in which first-trimester screening for PE was carried out using the Fetal Medicine Foundation (FMF) competing-risks model. The performance of screening was assessed by examining the area under the receiver-operating-characteristics curve (AUC) and detection rate (DR) at a 10% screen-positive rate (SPR). These indices were compared with those derived from the application of the FMF competing-risks model. The performance of screening was poor if no adjustment was made for the analyzer used to measure PlGF, which was different in the UK and Spain. Therefore, adjustment for the analyzer used was performed using simple linear regression.

RESULTS

The DRs at 10% SPR for early, preterm and all PE with the machine-learning model were 84.4% (95% CI, 67.2-94.7%), 77.8% (95% CI, 66.4-86.7%) and 55.7% (95% CI, 49.0-62.2%), respectively, with the corresponding AUCs of 0.920 (95% CI, 0.864-0.975), 0.913 (95% CI, 0.882-0.944) and 0.846 (95% CI, 0.820-0.872). This performance was achieved with the use of three of the biomarkers (MAP, UtA-PI and PlGF); inclusion of PAPP-A did not provide significant improvement in DR. The machine-learning model had similar performance to that achieved by the FMF competing-risks model (DR at 10% SPR, 82.7% (95% CI, 69.6-95.8%) for early PE, 72.7% (95% CI, 62.9-82.6%) for preterm PE and 55.1% (95% CI, 48.8-61.4%) for all PE) without requiring specific adaptations to the population.

CONCLUSIONS

A machine-learning model for first-trimester prediction of PE based on a neural network provides effective screening for PE that can be applied in different populations. However, before doing so, it is essential to make adjustments for the analyzer used for biochemical testing. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Three-dimensional echocardiography and strain cardiac imaging in women with pre-eclampsia with follow-up to 6 months postpartum

OBJECTIVE

Epidemiological studies have established that women with pre-eclampsia (PE) are at increased long-term cardiovascular risk. Mild cardiac functional changes have been documented during pregnancy in women with PE, but their evolution from presentation to the postpartum period remains poorly defined. The aim of this study was to assess biventricular cardiovascular indices using novel and sensitive two-dimensional and three-dimensional (3D) echocardiographic modalities in pregnancy and to track alterations in both risk factors and cardiovascular indices in the postpartum period.

METHODS

A total of 59 women with PE were examined at 34 (interquartile range, 31-37) weeks' gestation and at 2-3 days, 3 months and 6 months postpartum. During pregnancy, 118 women with a normotensive pregnancy were also recruited as controls. Biventricular ejection fraction and left ventricular mass were measured by 3D echocardiography. Biventricular global longitudinal strain and strain of the left atrium were assessed using speckle-tracking imaging.

RESULTS

In women with PE, compared with controls, there was lower left ventricular diastolic function (left atrial reservoir strain, 44.1% vs 49.2%) and increased left ventricular mass index (148 vs 128 g/m2 ), but there was no significant difference in right ventricular functional indices. These alterations in cardiac indices were mostly explained by differences in maternal risk factors. In the postpartum period, most cardiac indices improved by 3 months. Multivariable linear mixed-model analysis demonstrated that this improvement was mostly attributed to reduction in weight and blood pressure.

CONCLUSION

In women with PE, there is postpartum improvement in cardiac functional and structural indices in parallel with improvement in their risk factor profile. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Risk of fetal loss after chorionic villus sampling in twin pregnancy derived from propensity score matching analysis

OBJECTIVE

To estimate the risk of fetal loss associated with chorionic villus sampling (CVS) in twin pregnancy, using propensity score analysis.

METHODS

This was a multicenter cohort study of women with twin pregnancy undergoing ultrasound examination at 11-13 weeks' gestation, performed in eight fetal medicine units in which the leadership were trained at the Harris Birthright Research Centre for Fetal Medicine in London, UK, and in which the protocols for screening, invasive testing and pregnancy management are similar. The risk of death of at least one fetus was compared between pregnancies that had and those that did not have CVS, after propensity score matching (1:1 ratio). This procedure created two comparable groups by balancing the maternal and pregnancy characteristics that lead to CVS being performed, similar to how randomization operates in a randomized clinical trial.

RESULTS

The study population of 8581 twin pregnancies included 445 that had CVS. Death of one or two fetuses at any stage during pregnancy occurred in 11.5% (51/445) of pregnancies in the CVS group and in 6.3% (515/8136) in the non-CVS group (P < 0.001). The propensity score algorithm matched 258 cases that had CVS with 258 non-CVS cases; there was at least one fetal loss in 29 (11.2%) cases in the CVS group and in 35 (13.6%) cases in the matched non-CVS group (odds ratio (OR), 0.81; 95% CI, 0.48-1.35; P = 0.415). However, there was a significant interaction between the risk of fetal loss after CVS and the background risk of fetal loss; when the background risk was higher, the risk of fetal loss after CVS decreased (OR, 0.46; 95% CI, 0.23-0.90), while, in pregnancies with a lower background risk of fetal loss, the risk of fetal loss after CVS increased (OR, 2.45; 95% CI, 0.95-7.13). The effects were statistically significantly different (P-value of the interaction = 0.005). For a pregnancy in which the background risk of fetal loss was about 6% (the same as in our non-CVS population), there was no change in the risk of fetal loss after CVS, but, when the background risk was more than 6%, the posterior risk was paradoxically reduced, and when the background risk was less than 6%, the posterior risk increased exponentially; for example, if the background risk of fetal loss was 2.0%, the relative risk was 2.8 and the posterior risk was 5.6%.

CONCLUSION

In twin pregnancy, after accounting for the risk factors that lead to both CVS and spontaneous fetal loss and confining the analysis to pregnancies at lower prior risk, CVS seems to increase the risk of fetal loss by about 3.5% above the patient's background risk. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Three-dimensional echocardiography and cardiac strain imaging in women with gestational diabetes mellitus

OBJECTIVES

Gestational diabetes mellitus (GDM) is associated with premature cardiovascular disease and adverse cardiovascular outcome in the mother. Subclinical cardiac functional changes in the left ventricle have been reported during pregnancy in women with GDM using conventional echocardiography, but results are inconsistent. The aims of the current study were to assess whether GDM is associated with biventricular systolic dysfunction in the mother and whether these cardiac changes can be detected using the novel echocardiographic modalities of strain imaging and three-dimensional (3D) echocardiography.

METHODS

This was a cross-sectional study in women with GDM and controls examined at 26-40 weeks of gestation. All women underwent echocardiography, and 3D volumes of the left and right ventricles and left atrium were collected. Ejection fraction and left ventricular mass were measured using 3D echocardiography. Left ventricular mass was indexed to body surface area. Speckle-tracking echocardiography was used to assess global longitudinal strain of the left and right ventricles and strain of the left atrium.

RESULTS

The study population included 123 women with GDM and 246 controls. Women with GDM, compared to controls, were older (35.1 ± 5.2 vs 32.4 ± 5.5 years; P < 0.001), had higher body mass index (30.6 (interquartile range (IQR), 26.2-35.2) vs 27.5 (IQR, 24.7-30.7) kg/m² ; P < 0.001) and had higher systolic blood pressure (119.9 ± 11.2 vs 116.4 ± 12.0 mmHg; P = 0.007). In all women with GDM, there was good glycemic control. In women with GDM, compared to controls, there was lower global longitudinal strain of the left ventricle (-19.3% (IQR, -21.4 to -17.6%) vs -20.1% (IQR, -22.1 to -18.7%); P = 0.002) and right ventricle (-22.2% (IQR, -26.1 to -19.8%) vs -24.1% (IQR, -27.0 to -21.9%); P < 0.001). There was no significant difference between the groups in ejection fraction, left ventricular mass, diastolic function assessed by left atrial strain, or 3D functional indices.

CONCLUSIONS

Women with GDM, compared to women with uncomplicated pregnancy, have lower left and right ventricular myocardial deformation. Volumetric assessment using 3D echocardiography does not provide additional information about maternal cardiac function. Strain imaging is a sensitive echocardiographic modality to detect early cardiac functional changes in women with GDM. Further studies are needed to assess the pattern of deterioration of cardiac function with advancing age in women with a history of GDM. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal loss after chorionic villus sampling in twin pregnancy

OBJECTIVE

To estimate the chorionic villus sampling (CVS)-related risk of fetal loss in twin pregnancy after adjustment for chorionicity, nuchal translucency thickness (NT), intertwin discordance in crown-rump length (CRL), maternal demographic characteristics and serum pregnancy-associated plasma protein-A (PAPP-A) and free β-human chorionic gonadotropin (β-hCG).

METHODS

This was a multicenter study from eight fetal medicine units in which the leadership were trained at the Harris Birthright Research Centre for Fetal Medicine in London, UK, and in which the protocols for screening, invasive testing and pregnancy management are similar. Data were obtained prospectively from women with twin pregnancy undergoing routine ultrasound examination at 11-13 weeks' gestation. Multivariable logistic regression analysis with backward stepwise elimination was used to examine whether CVS provided a significant independent contribution to the prediction of risk of fetal loss after adjusting for maternal and pregnancy characteristics, including maternal age, racial origin and weight, method of conception, smoking status, parity, chorionicity, intertwin discordance in CRL, fetal NT ≥ 95^th percentile and free β-hCG and PAPP-A multiples of the median. Similarly, within the CVS group, multivariable logistic regression analysis was used to investigate the effect of the number of intrauterine needle insertions and size of the needle on the risk of fetal loss.

RESULTS

The study population of 8581 twin pregnancies undergoing ultrasound examination at 11-13 weeks' gestation included 316 dichorionic and 129 monochorionic twins that had CVS. First, in twin pregnancies undergoing CVS, compared to those not undergoing CVS, there was a 2-fold increased risk of fetal loss at < 24 weeks' gestation and of loss at any stage in pregnancy. Second, the factors providing a significant independent contribution to the prediction of miscarriage or fetal loss in twin pregnancy were increased maternal weight, black racial origin, monochorionicity, and more so monoamnionicity, large intertwin discordance in CRL and increased fetal NT, and, in the case of fetal loss at any stage, there was also a contribution from assisted conception and low serum PAPP-A. Third, after adjustment for maternal and pregnancy characteristics, CVS did not provide a significant contribution to the risk of fetal loss. Fourth, in twin pregnancies that had CVS, there was no significant contribution to fetal loss from the number of intrauterine needle insertions or needle size.

CONCLUSION

The 2-fold increased risk of fetal loss following CVS in twin pregnancy can, to a great extent, be explained by maternal and pregnancy characteristics rather than the invasive procedure itself. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

New approach for estimating risk of miscarriage after chorionic villus sampling

OBJECTIVE

To estimate the risk of miscarriage associated with chorionic villus sampling (CVS).

METHODS

This was a retrospective cohort study of women attending for routine ultrasound examination at 11 + 0 to 13 + 6 weeks' gestation at one of eight fetal-medicine units in Spain, Belgium and Bulgaria, between July 2007 and June 2018. Two populations were included: (1) all singleton pregnancies undergoing first-trimester assessment at Hospital Clínico Universitario Virgen de la Arrixaca in Murcia, Spain, that did not have CVS (non-CVS group); and (2) all singleton pregnancies that underwent CVS following first-trimester assessment at one of the eight participating centers (CVS group). We excluded pregnancies diagnosed with genetic anomalies or major fetal defects before or after birth, those that resulted in termination and those that underwent amniocentesis later in pregnancy. We used propensity score (PS) matching analysis to estimate the association between CVS and miscarriage. We compared the risk of miscarriage of the CVS and non-CVS groups after PS matching (1:1 ratio). This procedure creates two comparable groups balancing the maternal and pregnancy characteristics that are associated with CVS, in a similar way to that in which randomization operates in a randomized clinical trial.

RESULTS

The study population consisted of 22 250 pregnancies in the non-CVS group and 3613 in the CVS group. The incidence of miscarriage in the CVS group (2.1%; 77/3613) was significantly higher than that in the non-CVS group (0.9% (207/22 250); P < 0.0001). The PS algorithm matched 2122 CVS with 2122 non-CVS cases, of which 40 (1.9%) and 55 (2.6%) pregnancies in the CVS and non-CVS groups, respectively, resulted in a miscarriage (odds ratio (OR), 0.72 (95% CI, 0.48-1.10); P = 0.146). We found a significant interaction between the risk of miscarriage following CVS and the risk of aneuploidy, suggesting that the effect of CVS on the risk of miscarriage differs depending on background characteristics. Specifically, when the risk of aneuploidy is low, the risk of miscarriage after CVS increases (OR, 2.87 (95% CI, 1.13-7.30)) and when the aneuploidy risk is high, the risk of miscarriage after CVS is paradoxically reduced (OR, 0.47 (95% CI, 0.28-0.76)), presumably owing to prenatal diagnosis and termination of pregnancies with major aneuploidies that would otherwise have resulted in spontaneous miscarriage. For example, in a patient in whom the risk of aneuploidy is 1 in 1000 (0.1%), the risk of miscarriage after CVS will increase to 0.3% (0.2 percentage points higher).

CONCLUSIONS

The risk of miscarriage in women undergoing CVS is about 1% higher than that in women who do not have CVS, although this excess risk is not solely attributed to the invasive procedure but, to some extent, to the demographic and pregnancy characteristics of the patients. After accounting for these risk factors and confining the analysis to low-risk pregnancies, CVS seems to increase the risk of miscarriage by about three times above the patient's background risk. Although this is a substantial increase in relative terms, in pregnancies without risk factors for miscarriage, the risk of miscarriage after CVS remains low and similar to, or slightly higher than, that in the general population. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.