Predictive accuracy of second-trimester uterine artery Doppler indices for stillbirth: a systematic review and meta-analysis

An overview of diabetes mellitus in pregnant women with obesity

Rates of obesity are increasing world-wide with an estimated 1billion people projected to be obese by 2030 if current trends remain unchanged. Obesity currently considered one of the most significant associated factors of non-communicable diseases poses the greatest threat to health. Diabetes mellitus is an important metabolic disorder closely associated with obesity. It is therefore expected that with the increasing rates of obesity, the rates of diabetes in pregnancy will also be rising. This disorder may pre-date pregnancy (diagnosed or undiagnosed and diagnosed for the first time in pregnancy) or may be of onset in pregnancy. Irrespective of the timing of onset, diabetes in pregnancy is associated with both fetal and maternal complications. Outcomes are much better if control is maximised. Early diagnosis, multidisciplinary care and tailored management with optimum glycaemic control is associated with a significant reduction in not only pregnancy complications but long-term consequences on both the mother and offspring. This review brings together the current understanding of the pathogenesis of the endocrine derangements that are associated with diabetes in pregnancy how screening should be offered and management including pre-pregnancy care and the role of newer agents in management.

Fetal aortic isthmus Doppler assessment to predict the adverse perinatal outcomes associated with fetal growth restriction: systematic review and meta-analysis

PURPOSE

Fetal growth restriction (FGR) management and delivery planning is based on a multimodal approach. This meta-analysis aimed to evaluate the prognostic accuracies of the aortic isthmus Doppler to predict adverse perinatal outcomes in singleton pregnancies with FGR.

METHODS

PubMed, EMBASE, the Cochrane Library, ClinicalTrials.gov and Google scholar were searched from inception to May 2021, for studies on the prognostic accuracy of anterograde aortic isthmus flow compared with retrograde aortic isthmus flow in singleton pregnancy with FGR. The meta-analysis was registered on PROSPERO and was assessed according to PRISMA and Newcastle-Ottawa Scale. DerSimonian and Laird's random-effect model was used for relative risks, Freeman-Tukey Double Arcsine for pooled estimates and exact method to stabilize variances and CIs. Heterogeneity was quantified using I2 statistics.

RESULTS

A total of 2933 articles were identified through the electronic search, of which 6 studies (involving 240 women) were included. The quality evaluation of studies revealed an overall acceptable score for study group selection and comparability and substantial heterogeneity. The risk of perinatal death was significantly greater in fetuses with retrograde Aortic Isthmus blood flow, with a RR of 5.17 (p value 0.00001). Similarly, the stillbirth rate was found to have a RR of 5.39 (p value 0.00001). Respiratory distress syndrome had a RR of 2.64 (p value = 0.03) in the group of fetuses with retrograde Aortic Isthmus blood flow.

CONCLUSION

Aortic Isthmus Doppler study may add information for FGR management. However, additional clinical trial are required to assess its applicability in clinical practice.

Association between abnormal uterine artery pulsatility index and the risk of fetal congenital heart defects: a hospital-based cohort study

To explore the associations between high uterine artery pulsatility index (UtA-PI) values and congenital heart disease (CHD) risk and whether they differed between singleton and multiple pregnancies. This hospital-based cohort study involving 52,047 pregnant women who underwent prenatal examinations from 2012 to 2016. Infants born to the included pregnant women were followed until 42 days after birth to identify those with CHDs. Generalized estimating equations were used to estimate the associations of high right UtA-PI (> 95th percentile) values with maternal preeclampsia and fetal CHDs. Logistic regression analyses were conducted using path analysis models to quantify the effect of high right UtA-PI values on fetal CHD risk. A total of 42,552 women and 43,470 infants (147 with CHDs) were included. Preeclampsia risk was associated with a high right UtA-PI in singleton-pregnant women (adjusted PR, 3.01; 95% CI 2.57-3.52). CHD risk was marginally associated with a high right UtA-PI in singleton-pregnant women (adjusted PR, 2.26, 95% CI 1.03-4.95). Considering only two factors, 96.0% of the fetal CHD risk was mediated by preeclampsia in singleton-pregnant women, while 93.8% of the risk was related to a high right UtA-PI in multiple-pregnant women. A high right UtA-PI was marginally associated with an increased fetal CHD risk in singleton-pregnant women and might play an important role in multiple-pregnant women. Further studies are warranted to confirm these findings given the high loss to follow-up rate.

Identifying risk of stillbirth using machine learning

BACKGROUND

Previous predictive models using logistic regression for stillbirth do not leverage the advanced and nuanced techniques involved in sophisticated machine learning methods, such as modeling nonlinear relationships between outcomes.

OBJECTIVE

This study aimed to create and refine machine learning models for predicting stillbirth using data available before viability (22-24 weeks) and throughout pregnancy, as well as demographic, medical, and prenatal visit data, including ultrasound and fetal genetics.

STUDY DESIGN

This is a secondary analysis of the Stillbirth Collaborative Research Network, which included data from pregnancies resulting in stillborn and live-born infants delivered at 59 hospitals in 5 diverse regions across the United States from 2006 to 2009. The primary aim was the creation of a model for predicting stillbirth using data available before viability. Secondary aims included refining models with variables available throughout pregnancy and determining variable importance.

RESULTS

Among 3000 live births and 982 stillbirths, 101 variables of interest were identified. Of the models incorporating data available before viability, the random forests model had 85.1% accuracy (area under the curve) and high sensitivity (88.6%), specificity (85.3%), positive predictive value (85.3%), and negative predictive value (84.8%). A random forests model using data collected throughout pregnancy resulted in accuracy of 85.0%; this model had 92.2% sensitivity, 77.9% specificity, 84.7% positive predictive value, and 88.3% negative predictive value. Important variables in the previability model included previous stillbirth, minority race, gestational age at the earliest prenatal visit and ultrasound, and second-trimester serum screening.

CONCLUSION

Applying advanced machine learning techniques to a comprehensive database of stillbirths and live births with unique and clinically relevant variables resulted in an algorithm that could accurately identify 85% of pregnancies that would result in stillbirth, before they reached viability. Once validated in representative databases reflective of the US birthing population and then prospectively, these models may provide effective risk stratification and clinical decision-making support to better identify and monitor those at risk of stillbirth.

Doppler Indices of the Uterine, Umbilical and Fetal Middle Cerebral Artery in Diabetic versus Non-Diabetic Pregnancy: Systematic Review and Meta-Analysis

Background and Objectives: The aim of this study was to assess the differences in Doppler indices of the uterine (Ut), umbilical (UA), and middle cerebral artery (MCA) in diabetic versus non-diabetic pregnancies by conducting a comprehensive systematic review of the literature with a meta-analysis. Materials and Methods: PubMed, Web of Science, and SCOPUS were searched for studies that measured the pulsatility index (PI), resistance index (RI), and systolic/diastolic ratio index (S/D ratio) of the umbilical artery, middle cerebral artery, and uterine artery in diabetic versus non-diabetic pregnancies. Two reviewers independently evaluated the eligibility of studies, abstracted data, and performed quality assessments according to standardized protocols. The standardized mean difference (SMD) was used as a measure of effect size. Heterogeneity was assessed using the I2 statistic. Publication bias was evaluated by means of funnel plots. Results: A total of 62 publications were included in the qualitative and 43 in quantitative analysis. The UA-RI, UtA-PI, and UtA-S/D ratios were increased in diabetic compared with non-diabetic pregnancies. Subgroup analysis showed that levels of UtA-PI were significantly higher during the third, but not during the first trimester of pregnancy in diabetic versus non-diabetic pregnancies. No differences were found for the UA-PI, UA-S/D ratio, MCA-PI, MCA-RI, MCA-S/D ratio, or UtA-RI between diabetic and non-diabetic pregnancies. Conclusions: This meta-analysis revealed the presence of hemodynamic changes in uterine and umbilical arteries, but not in the middle cerebral artery in pregnancies complicated by diabetes.

Utilization of Uterine and Umbilical Artery Doppler in the Second and Third Trimesters to Predict Adverse Pregnancy Outcomes: A Nigerian Experience

Objective: To assess the utility of uterine and umbilical artery Doppler in the second and third-trimester in predicting adverse pregnancy outcomes.

Methodology: In a prospective longitudinal study, the demographic, clinical, Doppler ultrasound parameters of the uterine and umbilical arteries of 84 consecutive women attending the antenatal clinic at 22–24 weeks and 116 women at 30–34 weeks gestation and pregnancy outcomes were documented and analyzed.

Results: Pregnant women with adverse pregnancy outcomes had significantly higher second-trimester mean uterine systolic/diastolic (S/D) ratio (p = 0.001), pulsatility index (PI; p = 0.003), umbilical artery S/D (p = 0.016), and resistivity index (RI; p = 0.041) as well as higher third-trimester uterine S/D and PI. While pregnancies with adverse fetal outcomes showed significantly higher uterine artery S/D and PI at the second trimester, third-trimester uterine showed higher S/D, RI, and PI and umbilical artery PI than in women with normal fetal outcomes. The combination of uterine PI and early diastolic notch were predictors of maternal outcomes and correctly predicted 73% (p < 0.001) in the second trimester. By the third trimester, the uterine PI alone was the best predictor and accurately predicted about 62% of maternal outcomes (p = 0.028). In addition, the second-trimester uterine S/D and early diastolic notch and uterine PI in the third trimester correctly predicted 79% and 78% of fetal outcomes, respectively.

Conclusion: Among unselected pregnant women population, the second-trimester Doppler parameters are better predictors of maternal adverse pregnancy outcomes, while adverse fetal outcome prediction by uterine and umbilical Doppler at the second- and the third-trimester parameters are comparable.

Prediction of stillbirth: an umbrella review of evaluation of prognostic variables

BACKGROUND

Stillbirth accounts for over 2 million deaths a year worldwide and rates remains stubbornly high. Multivariable prediction models may be key to individualised monitoring, intervention or early birth in pregnancy to prevent stillbirth.

OBJECTIVES

To collate and evaluate systematic reviews of factors associated with stillbirth in order to identify variables relevant to prediction model development.

SEARCH STRATEGY

MEDLINE, Embase, DARE and Cochrane Library databases and reference lists were searched up to November 2019.

SELECTION CRITERIA

We included systematic reviews of association of individual variables with stillbirth without language restriction.

DATA COLLECTION AND ANALYSIS

Abstract screening and data extraction were conducted in duplicate. Methodological quality was assessed using AMSTAR and QUIPS criteria. The evidence supporting association with each variable was graded.

RESULTS

The search identified 1198 citations. Sixty-nine systematic reviews reporting 64 variables were included. The most frequently reported were maternal age (n = 5), body mass index (n = 6) and maternal diabetes (n = 5). Uterine artery Doppler appeared to have the best performance of any single test for stillbirth. The strongest evidence of association was for nulliparity and pre-existing hypertension.

CONCLUSION

We have identified variables relevant to the development of prediction models for stillbirth. Age, parity and prior adverse pregnancy outcomes had a more convincing association than the best performing tests, which were PAPP-A, PlGF and UtAD. The evidence was limited by high heterogeneity and lack of data on intervention bias.

TWEETABLE ABSTRACT

Review shows key predictors for use in developing models predicting stillbirth include age, prior pregnancy outcome and PAPP-A, PLGF and Uterine artery Doppler.

Third-trimester uterine artery Doppler for prediction of adverse outcome in late small-for-gestational-age fetuses: systematic review and meta-analysis

OBJECTIVE

To investigate the predictive ability for adverse perinatal outcome of abnormal third-trimester uterine artery Doppler in late small-for-gestational-age (SGA) fetuses.

METHODS

A systematic search was performed to identify relevant observational studies and randomized controlled trials evaluating the performance of abnormal third-trimester uterine artery Doppler for the prediction of adverse perinatal outcome in suspected SGA fetuses and SGA neonates. Abnormal uterine artery Doppler was defined as uterine artery pulsatility index > 95^th percentile or ≥ 2 SD above the mean, or bilateral uterine artery notching. Hierarchical summary receiver-operating-characteristics (ROC) curves were constructed using random-effects modeling. Bayesian analysis was used to calculate the posterior probability of adverse perinatal outcome following an abnormal or normal uterine artery Doppler assessment.

RESULTS

Seventeen observational studies (including 7552 fetuses either diagnosed with suspected SGA (n = 3461) or later diagnosed as a SGA neonate (n = 4091)) met the inclusion criteria; no randomized-controlled trials met the inclusion criteria. Summary ROC curves showed that, among suspected SGA fetuses, the best predictive accuracy of abnormal third-trimester uterine artery Doppler was for perinatal mortality and the worst was for composite adverse perinatal outcome, with areas under the summary ROC curves of 0.90 and 0.66, respectively. The corresponding positive and negative likelihood ratios were 16.5 and 0.6 for perinatal mortality and 2.82 and 0.65 for composite adverse perinatal outcome, respectively. Following an abnormal vs normal uterine artery Doppler assessment, the posterior risks for composite adverse perinatal outcome, admission to the neonatal intensive care unit, Cesarean section for intrapartum fetal compromise, 5-min Apgar score < 7, neonatal acidosis and perinatal death were: 52.3% vs 20.2%, 48.6% vs 18.7%, 23.1% vs 15.2%, 3.59% vs 1.32%, 9.15% vs 5.12% and 31.4% vs 1.64%, respectively.

CONCLUSION

Abnormal uterine artery Doppler in the third trimester appears to be moderately useful in predicting perinatal death in pregnancies with suspected SGA. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Does Uterine Doppler Add Information to the Cerebroplacental Ratio for the Prediction of Adverse Perinatal Outcome at the End of Pregnancy?

OBJECTIVE

To evaluate whether the addition of the mean uterine arteries pulsatility index (mUtA PI) to the cerebroplacental ratio (CPR) improves its ability to predict adverse perinatal outcome (APO) at the end of pregnancy.

METHODS

This was a prospective study of 891 fetuses that underwent an ultrasound examination at 34-41 weeks. The CPR and the mUtA PI were converted into multiples of the median (MoM) and the estimated fetal weight (EFW) into centiles according to local references. APO was defined as a composite of abnormal cardiotocogram, intrapartum pH requiring cesarean section, 5' Apgar score <7, neonatal pH <7.10 and admission to pediatric care units. The accuracies of the different parameters were evaluated alone and in combination with gestational characteristics using univariate and multivariate analyses by means of the Akaike Information Criteria (AIC) and the area under the curve (AUC). Finally, a comparison was similarly performed between the CPR and the cerebro-placental-uterine ratio (CPUR; CPR/mUtA PI) for the prediction of APO.

RESULTS

The univariate analysis showed that CPR MoM was the best parameter predicting APO (AIC 615.71, AUC 0.675). The multivariate analysis including clinical data showed that the best prediction was also achieved with the CPR MoM (AIC 599.39, AUC 0.718). Moreover, when EFW centiles were considered, the addition of UtA PI MoM did not improve the prediction already obtained with CPR MoM (AIC 591.36, AUC 0.729 vs. AIC 589.86, AUC 0.731). Finally, the prediction by means of CPUR did not improve that of CPR alone (AIC 623.38, AUC 0.674 vs. AIC 623.27, AUC 0.66).

CONCLUSION

The best prediction of APO at the end of pregnancy is obtained with CPR whatever is the combination of parameters. The addition of uterine Doppler to the information yielded by CPR does not result in any prediction improvement.

Placental Dysfunction Underlies Increased Risk of Fetal Growth Restriction and Stillbirth in Advanced Maternal Age Women

Pregnancies in women of advanced maternal age (AMA) are susceptible to fetal growth restriction (FGR) and stillbirth. We hypothesised that maternal ageing is associated with utero-placental dysfunction, predisposing to adverse fetal outcomes. Women of AMA (≥35 years) and young controls (20-30 years) with uncomplicated pregnancies were studied. Placentas from AMA women exhibited increased syncytial nuclear aggregates and decreased proliferation, and had increased amino acid transporter activity. Chorionic plate and myometrial artery relaxation was increased compared to controls. AMA was associated with lower maternal serum PAPP-A and sFlt and a higher PlGF:sFlt ratio. AMA mice (38-41 weeks) at E17.5 had fewer pups, more late fetal deaths, reduced fetal weight, increased placental weight and reduced fetal:placental weight ratio compared to 8-12 week controls. Maternofetal clearance of 14C-MeAIB and 3H-taurine was reduced and uterine arteries showed increased relaxation. These studies identify reduced placental efficiency and altered placental function with AMA in women, with evidence of placental adaptations in normal pregnancies. The AMA mouse model complements the human studies, demonstrating high rates of adverse fetal outcomes and commonalities in placental phenotype. These findings highlight placental dysfunction as a potential mechanism for susceptibility to FGR and stillbirth with AMA.

Interventions to prevent stillbirth

Stillbirth is one of the most distressing complications of pregnancy and still occurs far too frequently. The rate of stillbirth has been decreasing worldwide but room for improvement remains even in high-income countries. Risk factors for stillbirth have been identified in an effort to detect those women at increased risk. However, risk factors are non-specific and do not identify most stillbirths. Strategies employed to screen the general population such as assessment of fetal activity, fetal growth screening and biomarkers have also been used to identify increased risk for stillbirth. As with clinical risk factors, these methods are non-specific. Interventions to prevent stillbirth include antenatal testing of high-risk women, ultrasonographic assessments of fetal growth and Doppler velocimetry as well as iatrogenic preterm or term delivery. Additional research into the role of these interventions and better identification of those at high risk for stillbirth will help to achieve further stillbirth reduction.

Perinatal death investigations: What is current practice?

Perinatal death (PD) is a devastating obstetric complication. Determination of cause of death helps in understanding why and how it occurs, and it is an indispensable aid to parents wanting to understand why their baby died and to determine the recurrence risk and management in subsequent pregnancy. Consequently, a perinatal death requires adequate diagnostic investigation. An important first step in the analysis of PD is to identify the case circumstances, including relevant details regarding maternal history, obstetric history and current pregnancy (complications are evaluated and recorded). In the next step, placental examination is suggested in all cases, together with molecular cytogenetic evaluation and fetal autopsy. Investigation for fetal-maternal hemorrhage by Kleihauer is also recommended as standard. In cases where parents do not consent to autopsy, alternative approaches such as minimally invasive postmortem examination, postmortem magnetic resonance imaging, and fetal photographs are good alternatives. After all investigations have been performed it is important to combine findings from the clinical review and investigations together, to identify the most probable cause of death and counsel the parents regarding their loss.

Pregnancy subsequent to stillbirth: Medical and psychosocial aspects of care

Pregnancy after stillbirth presents unique challenges for families and healthcare providers. Medical surveillance and interventions must be optimized to improve outcomes and provide individualized support for families. A key component of acceptable care is psychosocial support that is delivered in a timely and sensitive manner by care providers with knowledge about the pervasive impact of stillbirth. With the lack of existing evidence to guide care, there is an urgent need for global leadership and research to address knowledge gaps.

Maternal Serum Analytes as Predictors of Fetal Growth Restriction with Different Degrees of Placental Vascular Dysfunction

Abnormal levels of maternal serum analytes have been associated with fetal growth restriction (FGR) and preeclampsia secondary to placental vascular dysfunction. Accurately identifying the FGR fetuses at highest risk for adverse outcomes remains challenging. Placental function can be assessed by Doppler analysis of the maternal and fetal circulation. Although the combination of multiple abnormal maternal serum analytes and abnormal Doppler findings is strongly associated with adverse outcomes, the predictive value remains too low to be used as a screening test in a low-risk population. Stratification of cases based on the severity of Doppler abnormalities may improve predictive models.