First-trimester uterine artery Doppler and hypertensive disorders in twin pregnancies: Use of twin versus singleton references

OBJECTIVE

To determine the association of first-trimester uterine artery Doppler with hypertensive disorders of pregnancy in twin pregnancies.

METHODS

This was a retrospective cohort study of twin pregnancies followed at the University Hospital Center of Central Lisbon, Portugal, between January 2010 and December 2022. First-trimester uterine artery pulsatility index (UtA-PI) was determined and compared between twin pregnancies (n = 454) and singleton pregnancies (n = 908), matched to maternal and pregnancy characteristics. Maternal characteristics and mean UtA-PI were analyzed for gestational age, birth weight, gestational hypertension, early- and late-onset pre-eclampsia, HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome, and preterm birth. Univariable and multivariable logistic regression models were used.

RESULTS

The mean first-trimester UtA-PI was significantly lower in dichorionic twins than in singletons (P < 0.001). To study hypertensive disorders of pregnancy in twins, 390 pregnancies were included: 311 (79.7%) dichorionic and 79 (20.3%) monochorionic twins. The observed rates of early- and late-onset pre-eclampsia, gestational hypertension, and HELLP syndrome were 1.0%, 4.4%, 7.4%, and 1.5%, respectively. We achieved a 100% detection rate for early-onset pre-eclampsia using the UtA-PI 90th centile for twins. However, when singleton references were considered, the detection rate decreased to 50%. UtA-PI at or above the 95th centile was associated with increased odds for preterm birth before 32 weeks (adjusted odds ratio 4.1, 95% confidence interval 1.0-16.7, P = 0.043).

CONCLUSIONS

Unless other major risk factors for hypertensive disorders are present, women with low UtA-PI will probably not benefit from aspirin prophylaxis. Close monitoring of all twin pregnancies for hypertensive disorders is still recommended.

Screening for preeclampsia in twin pregnancies

Twin pregnancies are an important risk factor for preeclampsia, a hypertensive disorder of pregnancy that is associated with a significant risk of maternal and perinatal morbidity. Given the burden of preeclampsia, the identification of women at high risk in early pregnancy is essential to allow for preventive strategies and close monitoring. In singleton pregnancies, the risk factors for preeclampsia are well established, and a combined first-trimester prediction model has been shown to adequately predict preterm disease. Furthermore, intervention with low-dose aspirin at 150 mg/day in those identified as high-risk reduces the rate of preterm preeclampsia by 62%. In contrast, risk factors for preeclampsia in twin pregnancies are less established, the proposed screening models have shown poor performance with high false-positive rates, and the benefit of aspirin for the prevention of preeclampsia is not clearly demonstrated. In this review, we examine the literature assessing prediction and prevention of preeclampsia in twin pregnancies.

A Review of Roles of Uterine Artery Doppler in Pregnancy Complications

The invasion of trophoblasts into the uterine decidua and decidual vessels is critical for the formation of placenta. The defects of placentation are related to the etiologies of preeclampsia (PE), fetal growth restriction (FGR), and small-for-gestational age (SGA) neonates. It is possible to predict significant vascular events during pregnancy through uterine artery Doppler (UAD). From the implantation stage to the end of pregnancy, detecting changes in uterine and placental blood vessels can provide a favorable diagnostic instrument for pregnancy complications. This review aims to collect literature about the roles of UAD in pregnancy complications. We consider all relevant articles in English from January 1, 1983 to October 30, 2021. Predicting pregnancy complications in advance allows practitioners to carry out timely interventions to avoid or lessen the harm to mothers and neonates. Administering low-dose aspirin daily before 16 weeks of pregnancy can significantly reduce the incidence of pregnancy complications. From early pregnancy to late pregnancy, UAD can combine with other maternal factors, biochemical indicators, and fetal measurement data to identify high-risk population. The identification of high-risk groups can also lessen maternal mortality. Besides, through moderate risk stratification, stringent monitoring for high-risk pregnant women can be implemented, decreasing the incidence of adversities.

Prediction of twin pregnancy preeclampsia based on clinical risk factors, early pregnancy serum markers, and uterine artery pulsatility index

Objectives:

To investigate whether a combination of clinical risk factors, early pregnancy serum markers, and uterine artery pulsatility index (UTPI) can be used to predict twin preeclampsia (PE).

Methods:

This case control study included women with twin pregnancies who had undergone obstetrics treatments and gave birth at the Huzhou Maternity and Child Health Care Hospital from October 2018 to November 2020. Patients with PE comprised study group, and patients without PE comprised control group based on selection criteria and a 1:1 ratio. Statistical analysis was performed using clinical risk factors, early pregnancy serum markers, and UTPIs, and the area under the receiver operating curve (AUC. Sensitivity, and the specificity of different combinations of these variables were calculated to predict PE in women with twin pregnancy.

Results:

Logistic regression analysis revealed four independent predictors for the onset of PE during twin pregnancies: first delivery (OR, 7.51; P=0.045), conception method (OR, 7.11; P=0.036), β-HCG level (per SD OR, 2.73; P=0.026), and UTPI (OR, 0.17; P=0.043). First-delivery and IVF pregnancy methods both lead to a 7-fold increase in the PE risk during twin pregnancies. Every one sigma (standard deviation) increase in the β-HCG level led to a 2.73-fold increase in the PE risk. Every UTPI increment by 1.0 reduces the risk of PE by 83%. The prediction efficiencies were based on an AUC of 0.837, a sensitivity of 69%, and a specificity of 92% for the clinical risk factors; an AUC of 0.800, a sensitivity of 81%, and specificity of 78% for the β-HCG level, and an AUC of 0.814, a sensitivity of 88%, and a specificity of 65% for the UTPI. AUC was 0.928, sensitivity 85%, and a specificity 88% after applying the three types of indicators together for prediction.

Conclusions:

By combining early pregnancy serum markers (β-HCG), and UTPI, the predictive value for PE during twin pregnancy is improved together with its sensitivity and specificity.

A Review of Research Progress of Pregnancy with Twins with Preeclampsia

Preeclampsia has a significant long-term effect on the health of both mothers and babies. Preeclampsia-related pregnancy complications increase the morbidity and mortality of pregnant women and their fetuses by 5-8%. The recent advancement of assisted reproductive technology, combined with a rise in the number of elderly pregnant women, has resulted in pregnancy incidence with twins. Twins pregnant women have a 2-3 times greater risk of developing preeclampsia than singleton pregnant women, and it happens sooner and progresses faster. It is more severe and may appear in an atypical way. End-organ damage, such as renal failure, stroke, cardiac arrest, pulmonary edema, placental abruption, and cesarean section, are related maternal complications. Fetal growth retardation, stillbirth, and premature delivery with obstetric signs are all fetal complications. According to studies, all multiple pregnancies can take low-dose aspirin (60-150 mg) to minimize the risk of preeclampsia. To improve pregnancy outcomes and reduce the inherent risk of pregnancy with twins, twins should be handled as a high-risk pregnancy and treated differently than singletons. The literature on twin pregnancy with preeclampsia is the subject of this review. It will examine the current state of research on preeclampsia in pregnancy with twins, including the occurrence, diagnosis, and pathophysiological process. Moreover, the effect of pregnancy with twins on the perinatal outcome and pregnancy management of pregnancy with twins, including blood pressure management and preeclampsia prevention and treatment, is examined in this literature review. The goal is to figure out what kind of diagnosis and care you may need.

Multiple Gestations and Hypertensive Disorders of Pregnancy: What Do We Know?

PURPOSE OF REVIEW

The occurrence of hypertensive disorders of pregnancy (HDP) including gestational hypertension, chronic hypertension, preeclampsia, and eclampsia is proportional to the number of fetuses: singletons 6.5%, twins 12.7%, and triplets 20.0%. Literature on HDP in multifetal gestation is sparse compared with singletons. We aim to summarize the current evidence on HDP, specifically in twins.

RECENT FINDINGS

HDP occurs more frequently, at an earlier gestational age, and can present more severely and atypically in twin pregnancies. HDP in twins carries a higher risk of maternal/fetal morbidity and mortality including renal failure, stroke, cardiac arrest, pulmonary edema, placental abruption, cesarean delivery, fetal growth restriction, and iatrogenic preterm delivery. Low-dose aspirin (60-150 mg) should be initiated in all multifetal pregnancies to reduce the risk of preeclampsia. To improve outcomes and reduce inherent risks associated with multiple gestations, twins should be managed as high-risk pregnancies, and different from singletons.

Screening for preeclampsia in low-risk twin pregnancies at early gestation

INTRODUCTION

Preeclampsia affects about 10% of twin pregnancies and significantly increases the risk of adverse pregnancy outcomes. However, screening models for preeclampsia in twin pregnancies remain elusive. The present study aimed to evaluate the performance of a multi-marker first trimester preeclampsia screening model in low-risk twin pregnancies.

MATERIAL AND METHODS

Between 2014 and 2017, we prospectively assessed first trimester biomarkers for preeclampsia in a 'low-risk' twin pregnancy cohort at a single center. Multiple logistic regression was used to determine significant predictors for early preeclampsia (occurring prior to 34 weeks) and late preeclampsia (occurring after 34 weeks). The performance of the screening models fitted using the significant predictors was calculated using receiver operating characteristics curves, and internal validation was performed using bootstrapping.

RESULTS

A total of 769 twin pregnancies were included in the study. Early preeclampsia and late preeclampsia developed in 27 (3.5%) and 59 (7.7%) cases, respectively. Logistic regression analyses showed that maternal age, body mass index, mean artery pressure and placental growth factor were significant predictors for early preeclampsia. Maternal age, body mass index, mean artery pressure and pregnancy-associated plasma protein A were significant for late preeclampsia. Uterine artery pulsatility index was not predictive of either early or late preeclampsia. For the fitted screening model of early and late preeclampsia, the areas under receiver operating characteristics curves were 0.82 (95% confidence interval [CI] 0.76-0.88) and 0.66 (95% CI 0.59-0.73), which were expected to decrease to 0.77 and 0.60, respectively, based on bootstrapping; the positive predictive values were 10.2% and 12.5%; and the estimated detection rates were 40.7% and 22.0%, respectively, at a false-positive rate of 10%.

CONCLUSIONS

A multi-marker screening model for preeclampsia in low-risk twin pregnancies, using a modified version of Fetal Medicine Foundation predictors in singletons, does not perform well. Uterine artery pulsatility index is of little value in screening for preeclampsia in low-risk twin pregnancies.

Uterine artery pulsatility index as a relevant parameter in the prediction of preeclampsia

Preeclampsia is a clinical syndrome that occurs in 5-10% of pregnancies with increased perinatal morbidity and mortality. According to ISUOG (International Society of Ultrasound in Obstetrics & Gynecology), the use of the uterine artery pulsatility index (PI) is an important sensitive method in predicting the risk of preeclampsia. This study is to emphasize the value of PI as a more relevant predictive parameter in the detection of preeclampsia in the second trimester compared to the presence of isolated uterine artery notch. For the above purpose, 96 patients were examined at the University Clinic of Gynecology and Obstetrics in Skopje, divided into 2 groups: study and control group. The study group consisted of 48 patients from 14 to 20 gestational weeks with present uterine artery notch, being the main inclusion criterion. The control group consisted of 48 pregnant patients at the same gestational age with absence of uterine artery notch. In the study group, 43.7% developed clinical syndrome of preeclampsia. The resistance index (RI) value was up to 0.73 and the predictive value of the RI was 57.1%. In patients who developed preeclampsia syndrome, the value of the PI above 1.75 was of much greater predictive value, with value of 71.4%. The sensitivity of these values was 88%, which is a reliable parameter. PI is a reliable parameter in detecting the risk of developing preeclampsia and an indicator of great clinical significance in the daily practice in perinatology. Keywords: preeclampsia; prediction; pulsatility index

Prediction of pregnancy complications by second-trimester uterine artery Doppler assessment in monochorionic twins

PURPOSE

We aimed to investigate whether transabdominal uterine artery (UtA) pulsatility index (PI) differs between monochorionic (MC) diamniotic and dichorionic (DC) twins and is useful to predict pregnancy complications.

METHODS

A total of 406 uncomplicated twin pregnancies (94 MC, 312 DC) were examined at 22⁺⁰ -24⁺⁶ weeks and compared for demographic characteristics, mean UtA PI, presence of notch, development of preeclampsia, fetal growth restriction (FGR), placental abruption, intrauterine fetal death and preterm delivery. Mann-Whitney and Fisher's exact tests were performed for continuous and categorical variables, respectively. Sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio were calculated for mean PI >95th percentile, presence of notch, and presence of either elevated PI or notch.

RESULTS

Median mean UtA PI was 0.68 in DC and 0.75 in MC pregnancies (P = .005). Bilateral notches were observed in one MC pregnancy; unilateral notch was seen in 8 DC (2.6%) and 5 MC diamniotic (5.3%) pregnancies. FGR occurred more frequently in DC twin pregnancies, while intrauterine fetal death in MC. Overall, the sensitivity of the parameters tested was low. Pregnancies with both PI above 95th percentile and presence of notch were all associated with complications, particularly FGR.

CONCLUSION

MC pregnancies have higher mean UtA PI. UtA screening in twins shows lower performances than in singletons for the detection of complications.

Competing-risks model in screening for pre-eclampsia in twin pregnancy according to maternal factors and biomarkers at 11-13 weeks' gestation

OBJECTIVE

To develop a model for screening for pre-eclampsia (PE) in twin pregnancies based on maternal demographic characteristics and medical history and biomarkers at 11-13 weeks' gestation.

METHODS

This was a screening study in twin pregnancies at 11-13 weeks' gestation. Bayes theorem was used to combine the a-priori risk from maternal factors with various combinations of uterine artery pulsatility index (UtA-PI), mean arterial pressure (MAP), serum pregnancy-associated plasma protein-A (PAPP-A) and placental growth factor (PlGF) multiples of the median (MoM) values. The performance of screening for PE requiring delivery at < 32, < 37 and < 42 weeks' gestation was estimated in 1100 twin pregnancies and 35 948 singleton pregnancies with complete data on UtA-PI, MAP, PlGF and PAPP-A.

RESULTS

In twin pregnancies that developed PE, the values of MAP and UtA-PI were increased and the values of PlGF and PAPP-A were decreased. The distributions of log₁₀ MoM values of biomarkers with gestational age at delivery were similar to those that were previously reported in singleton pregnancies and it was therefore assumed that the same model could be used for both singleton and twin pregnancies. The performance of screening for PE by maternal factors was improved by the addition of MAP, UtA-PI and PlGF; there was no further improvement with the addition of PAPP-A. In a mixed population of singleton and twin pregnancies, combined screening by maternal factors, MAP, UtA-PI and PlGF and risk cut-off of 1 in 75 for PE at < 37 weeks, the detection rate of PE at < 32, < 37 and < 42 weeks in singleton pregnancies was 91%, 77% and 57%, respectively, at a screen-positive rate (SPR) of 13%; the respective rates for twin pregnancies were 100%, 99% and 97%, at a SPR of 75%.

CONCLUSION

First-trimester combined screening for PE in singleton pregnancies can be adapted for screening in twins, leading to detection of nearly all affected cases but at a high SPR. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Intertwin discrepancy in middle cerebral artery peak systolic velocity and third-trimester fetal growth restriction in monochorionic-diamniotic twin pregnancy

OBJECTIVES

To assess the role of intertwin discrepancy in middle cerebral artery peak systolic velocity (MCA-PSV) for the prediction of late selective intrauterine growth restriction (sIUGR) at birth and birth weight discrepancy of > 25% (BW-25) in otherwise uncomplicated monochorionic-diamniotic (MCDA) twin pregnancies.

METHODS

This was a cohort study including all MCDA pregnancies followed in a tertiary fetal medicine unit between 2008 and 2013. Exclusion criteria were referral after first trimester, abnormal karyotype, structural anomalies, twin-to-twin transfusion syndrome, twin anemia-polycythemia sequence and sIUGR detected before 28 weeks. MCA-PSV values of both twins measured in the second trimester (18-24 weeks) and early third trimester (26-32 weeks) were converted in multiples of the median (MoM). sIUGR was defined as birth weight < 5(th) centile. The relationship between MCA-PSV discrepancy, sIUGR and BW-25 was assessed by logistic regression analysis. Receiver-operating characteristics (ROC) curves were used to ascertain the predictive value of MCA-PSV discrepancy for such complications.

RESULTS

In total, 136 MCDA twin pregnancies were included in the analysis. Thirty (22.1%) were complicated with sIUGR at birth and 12 (8.8%) were complicated with BW-25. Logistic regression analysis identified MCA-PSV discrepancy as an independent predictor for sIUGR. ROC curves identified third-trimester MCA-PSV discrepancy as the best predictor for both sIUGR (area under ROC curve (AUC), 0.73 (95% CI, 0.62-0.85)) and BW-25 (AUC, 0.79 (95% CI, 0.65-0.93)). The optimal cut-off point for MCA-PSV discrepancy was 0.30 MoM (sensitivity, 70% and specificity, 69% for sIUGR; sensitivity, 83% and specificity, 72% for BW-25).

CONCLUSION

In MCDA twin pregnancies, MCA-PSV discrepancy is associated with both sIUGR at birth and BW discordance. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

First- and second-trimester maternal serum markers of pre-eclampsia in twin pregnancy

OBJECTIVE

To evaluate the distribution of first- and second-trimester maternal serum markers in twin pregnancy with and without pre-eclampsia.

METHODS

One-hundred and forty-four twin and 109 unaffected singleton pregnancies were recruited from the same institution. First- and second-trimester maternal blood samples were stored and measured retrospectively for serum placental growth factor (PlGF), pregnancy-associated plasma protein-A (PAPP-A), free β-human chorionic gonadotropin (β-hCG) and α-fetoprotein (AFP). All had measurement of first-trimester serum markers, and 167 (66%) had second-trimester tests. Values were expressed in multiples of the gestation-specific median (MoMs) in singletons, adjusted for maternal weight, as appropriate.

RESULTS

Pre-eclampsia was diagnosed in 12 (9.0%) twin pregnancies of 133 continuing beyond 22 weeks. In unaffected twin pregnancies, all serum markers were statistically significantly increased (P < 0.0001), consistent with a doubling of concentration. Among twin pregnancies, those with pre-eclampsia had a significantly reduced median PlGF compared with surviving unaffected twin pregnancies (0.96 MoM vs 1.46 MoM; P < 0.0002, two-tailed), whilst median PAPP-A, which is known to be reduced in affected singleton pregnancies, was increased (3.91 MoM vs 2.43 MoM; P < 0.0005, two-tailed). The levels of free β-hCG (P < 0.02) and AFP (P < 0.05) were also significantly raised, but to a lesser extent than was the level of PAPP-A. Using a logistic regression algorithm based on first- and second-trimester PlGF and PAPP-A, together with previously published uterine artery Doppler and mean arterial pressure measurements in the same series, the predicted pre-eclampsia detection rate was 65% for a 10% false-positive rate.

CONCLUSIONS

In twin pregnancy, the predicted detection rate of pre-eclampsia using first- and second-trimester maternal serum and biophysical markers is good. In contrast to singleton pregnancy, PAPP-A levels are raised in the first trimester of twin pregnancies destined to develop pre-eclampsia and therefore a different prediction algorithm is needed. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Development of prenatal screening--A historical overview

The first prenatal screening test to be introduced was based on a single maternal serum marker of neural tube defects. Since then various prenatal screening concepts have been developed, the most successful being Down syndrome risk estimation using multiple serum and ultrasound markers. Today a completely new approach to aneuploidy screening is available based on maternal plasma cell-free DNA testing. This has the potential to markedly improve screening performance but routine testing is currently too expensive in a public health setting. However, it can be cost-effective when used in combination with existing multi-maker tests. Some are beginning to broaden prenatal screening to include pregnancy complications such as pre-eclampsia that can be prevented using soluble low-dose aspirin treatment started before 16 weeks of gestation. Prenatal screening for cardiac abnormalities, fragile X syndrome and recessive genetic disorders is underutilized and public health planners should considered a more widespread application of available methods.

First-trimester uterine artery Doppler analysis in the prediction of later pregnancy complications

Uterine artery Doppler waveform analysis has been extensively studied in the second trimester of pregnancy as a predictive marker for the later development of preeclampsia and fetal growth restriction. The use of Doppler interrogation of this vessel in the first trimester has gained momentum in recent years. Various measurement techniques and impedance indices have been used to evaluate the relationship between uterine artery Doppler velocimetry and adverse pregnancy outcomes. Overall, first-trimester Doppler interrogation of the uterine artery performs better in the prediction of early-onset than late-onset preeclampsia. As an isolated marker of future disease, its sensitivity in predicting preeclampsia and fetal growth restriction in low risk pregnant women is moderate, at 40–70%. Multiparametric predictive models, combining first-trimester uterine artery pulsatility index with maternal characteristics and biochemical markers, can achieve a detection rate for early-onset preeclampsia of over 90%. The ideal combination of these tests and validation of them in various patient populations will be the focus of future research.