The incremental yield of prenatal exome sequencing over chromosome microarray for congenital heart abnormalities: A systematic review and meta-analysis

OBJECTIVES

To determine the incremental yield of prenatal exome sequencing (PES) over standard testing in fetuses with an isolated congenital heart abnormality (CHA), CHA associated with extra-cardiac malformations (ECMs) and CHA dependent upon anatomical subclassification.

METHODS

A systematic review of the literature was performed using MEDLINE, EMBASE, Web of Science and grey literature January 2010-February 2023. Studies were selected if they included greater than 20 cases of prenatally diagnosed CHA when standard testing (QF-PCR/chromosome microarray/karyotype) was negative. Pooled incremental yield was determined. PROSPERO CRD 42022364747.

RESULTS

Overall, 21 studies, incorporating 1957 cases were included. The incremental yield of PES (causative pathogenic and likely pathogenic variants) over standard testing was 17.4% (95% CI, 13.5%-21.6%), 9.3% (95% CI, 6.6%-12.3%) and 35.9% (95% CI, 21.0%-52.3%) for all CHAs, isolated CHAs and CHAs associated with ECMs. The subgroup with the greatest yield was complex lesions/heterotaxy; 35.2% (95% CI 9.7%-65.3%). The most common syndrome was Kabuki syndrome (31/256, 12.1%) and most pathogenic variants occurred de novo and in autosomal dominant (monoallelic) disease causing genes (114/224, 50.9%).

CONCLUSION

The likelihood of a monogenic aetiology in fetuses with multi-system CHAs is high. Clinicians must consider the clinical utility of offering PES in selected isolated cardiac lesions.

Externally validated prediction models for pre-eclampsia: systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to evaluate the performance of existing externally validated prediction models for pre-eclampsia (PE) (specifically, any-onset, early-onset, late-onset and preterm PE).

METHODS

A systematic search was conducted in five databases (MEDLINE, EMBASE, Emcare, CINAHL and Maternity & Infant Care Database) and using Google Scholar/reference search to identify studies based on the Population, Index prediction model, Comparator, Outcome, Timing and Setting (PICOTS) approach until 20 May 2023. We extracted data using the CHARMS checklist and appraised the risk of bias using the PROBAST tool. A meta-analysis of discrimination and calibration performance was conducted when appropriate.

RESULTS

Twenty-three studies reported 52 externally validated prediction models for PE (one preterm, 20 any-onset, 17 early-onset and 14 late-onset PE models). No model had the same set of predictors. Fifteen any-onset PE models were validated externally once, two were validated twice and three were validated three times, while the Fetal Medicine Foundation (FMF) competing-risks model for preterm PE prediction was validated widely in 16 different settings. The most common predictors were maternal characteristics (prepregnancy body mass index, prior PE, family history of PE, chronic medical conditions and ethnicity) and biomarkers (uterine artery pulsatility index and pregnancy-associated plasma protein-A). The FMF model for preterm PE (triple test plus maternal factors) had the best performance, with a pooled area under the receiver-operating-characteristics curve (AUC) of 0.90 (95% prediction interval (PI), 0.76-0.96), and was well calibrated. The other models generally had poor-to-good discrimination performance (median AUC, 0.66 (range, 0.53-0.77)) and were overfitted on external validation. Apart from the FMF model, only two models that were validated multiple times for any-onset PE prediction, which were based on maternal characteristics only, produced reasonable pooled AUCs of 0.71 (95% PI, 0.66-0.76) and 0.73 (95% PI, 0.55-0.86).

CONCLUSIONS

Existing externally validated prediction models for any-, early- and late-onset PE have limited discrimination and calibration performance, and include inconsistent input variables. The triple-test FMF model had outstanding discrimination performance in predicting preterm PE in numerous settings, but the inclusion of specialized biomarkers may limit feasibility and implementation outside of high-resource settings. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Perinatal and neonatal outcomes of high-risk asymptomatic women from a specialist preterm birth surveillance clinic

OBJECTIVES

To report the perinatal outcomes of high-risk asymptomatic women who attended a specialist preterm surveillance clinic (PSC) to undergo screening for spontaneous preterm birth (PTB) in Ireland.

METHODS

Single center, retrospective cohort study of asymptomatic high risk women who attended the PSC between January 2019 and December 2022. A comprehensive database of all patients who attended the clinic during the study period was constructed and analyzed. Overall outcomes were reported, and stratified per the occurrence of preterm or term birth. Iatrogenic PTBs were included in the outcome data.

RESULTS

Following exclusions for loss-to-follow-up, 762 cases were analyzed, constituting 2262 PSC visits. Of those, 183 women were prescribed progesterone (24.0 %), and 100 women underwent cervical cerclage (13.1 %) to prevent spontaneous PTB. Overall, 2.4 %, 6.2 % and 18.6 % of participants gave birth prior to 30 weeks, 34 weeks, and 37 weeks, respectively. The median gestational age at birth for the entire cohort was 38.6 weeks (inter-quartile range (IQR) 37.2-39.6 weeks). Women who delivered < 37 weeks were significantly more likely to be smokers (p = 0.030), have a previous spontaneous PTB (p = 0.016), have multiple pregnancies (p < 0.001), type 1 or 2 diabetes (p = 0.044), or have a previous full dilatation caesarean section birth (p = 0.024). Infants born prior to 37 weeks were more likely to have a lower median birthweight (2270 vs 3300 g, p < 0.001), be admitted to a neonatal intensive care unit (53.8 % vs 2.3 %, p < 0.001) or experience short-term morbidity, including respiratory support (38.0 % vs 1.6 %, p < 0.001).

CONCLUSIONS

Over 80% of women deemed to be at high risk of PTB gave birth at term gestations following attendance at a PSC during pregnancy. Most women can be successfully managed without interventions, instead employing a policy of serial cervical surveillance, to identify those at greatest risk of PTB.

Performance of QUiPP app v.2 tool for prediction of preterm birth in asymptomatic high-risk women attending preterm specialist clinic: external validation study

OBJECTIVES

External validation of the QUiPP App v.2 algorithms in an independent cohort of high-risk asymptomatic women attending an Irish preterm birth surveillance clinic (PSC).

METHODS

Retrospective, single center, observational study assessing discrimination and calibration of the QUiPP App v.2 at the six pre-determined clinical time points (birth prior to 30, 34, 37 weeks of pregnancy, and birth within one, two and four weeks of testing). Discrimination was assessed by estimating the area under the receiver-operating characteristics (ROC) curve (AUC) and sensitivity at fixed false-positive rates of 5%, 10% and 20%. Model calibration was assessed to evaluate the concordance between expected and observed outcomes. P-values <0.05 were considered statistically significant. No adjustments for treatment effects were made.

RESULTS

762 women and 1660 preterm birth surveillance clinic (PSC) visits utilizing the QUiPP between 2019 and 2022 were analyzed. The study population included 142 patients who later experienced a PTB (18.6%). QUiPP's performance to predict short-term outcomes such as birth within one week (AUC 0.866, 95% CI 0.755-0.955), two weeks (AUC 0.721, 95% CI 0.569-0.854) and four weeks (AUC 0.775, 95% CI 0.699-0.842), and delivery before 30 weeks (AUC 0.747, 95% CI 0.613-0.865) was superior to its ability to predict longer-term outcomes (birth <37 weeks; AUC 0.631, 95% CI 0.596-0.668). Calibration was generally good for low-risk results as the predicted risk in these patients tended to match the observed incidence. However, in women deemed to be at greater risk of delivery, the predicted probability superseded the observed incidence of PTB.

CONCLUSION

QUiPP accurately discriminates women who are at short-term risk of PTB. A treatment paradox may influence calibration in high-risk women. Further research is needed to ascertain if QUiPP treatment thresholds can be safely adjusted in women receiving prophylactic treatment to prevent PTB, and whether this improves outcomes. This article is protected by copyright. All rights reserved.

Successful pregnancy rates amongst patients undergoing ovarian tissue cryopreservation for non-malignant indications: A systematic review and meta-analysis

BACKGROUND

Ovarian tissue cryopreservation (OTC) is a fertility preservation method that has been clinically applied for almost 30 years. Studies specifically evaluating patients presenting with non-malignant indications for OTC and their subsequent pregnancy rates are limited.

OBJECTIVE

To summarise the evidence on the rates of successful pregnancy amongst women who have undergone OTC for non-malignant indications.

METHODS

A systematic review with meta-analysis (PROSPERO registration CRD42022307925) was conducted to investigate the pregnancy outcomes of patients who have undergone ovarian tissue cryopreservation for non-malignant indications. Articles published in EMBASE and Ovid MEDLINE before October 2022 were screened for inclusion based on the following criteria: original human studies pertaining to OTC with a defined non-malignant cohort and pregnancy outcomes. The successful pregnancy rates were pooled with a random-effects model of double-arcsine transformed proportions. Sensitivity analysis involved pooling the results of studies with a low risk of bias after being assessed with NIH tools.

RESULTS

The database search retrieved 3,225 results, of which 16 were included in the meta-analysis. The pooled successful pregnancy rate was 23.52 % (16 studies, 95 % CI 6.48 to 44.79 %). When subgroup analysis of study types was performed, the successful pregnancy rate was higher amongst case series (47.02 %, 9 studies, 95 % CI 6.98 to 89.00 %) than cohort studies (14.64 %, 7 studies, 95 % CI 3.59 to 29.78 %). Sensitivity analysis limited to studies at low risk of bias revealed a similar pooled successful pregnancy rate of 23.35 % (12 studies, 95 % CI 2.50 to 51.96 %).

CONCLUSIONS

Approximately one quarter of women who underwent OTC for non-malignant indications had a successful pregnancy. These findings are clinically important for fertility preservation counselling by providing greater evidence for more informed care.

Embryo selection through artificial intelligence versus embryologists: a systematic review

STUDY QUESTION

What is the present performance of artificial intelligence (AI) decision support during embryo selection compared to the standard embryo selection by embryologists?

SUMMARY ANSWER

AI consistently outperformed the clinical teams in all the studies focused on embryo morphology and clinical outcome prediction during embryo selection assessment.

WHAT IS KNOWN ALREADY

The ART success rate is ∼30%, with a worrying trend of increasing female age correlating with considerably worse results. As such, there have been ongoing efforts to address this low success rate through the development of new technologies. With the advent of AI, there is potential for machine learning to be applied in such a manner that areas limited by human subjectivity, such as embryo selection, can be enhanced through increased objectivity. Given the potential of AI to improve IVF success rates, it remains crucial to review the performance between AI and embryologists during embryo selection.

STUDY DESIGN SIZE DURATION

The search was done across PubMed, EMBASE, Ovid Medline, and IEEE Xplore from 1 June 2005 up to and including 7 January 2022. Included articles were also restricted to those written in English. Search terms utilized across all databases for the study were: ('Artificial intelligence' OR 'Machine Learning' OR 'Deep learning' OR 'Neural network') AND ('IVF' OR 'in vitro fertili*' OR 'assisted reproductive techn*' OR 'embryo'), where the character '*' refers the search engine to include any auto completion of the search term.

PARTICIPANTS/MATERIALS SETTING METHODS

A literature search was conducted for literature relating to AI applications to IVF. Primary outcomes of interest were accuracy, sensitivity, and specificity of the embryo morphology grade assessments and the likelihood of clinical outcomes, such as clinical pregnancy after IVF treatments. Risk of bias was assessed using the Modified Down and Black Checklist.

MAIN RESULTS AND THE ROLE OF CHANCE

Twenty articles were included in this review. There was no specific embryo assessment day across the studies-Day 1 until Day 5/6 of embryo development was investigated. The types of input for training AI algorithms were images and time-lapse (10/20), clinical information (6/20), and both images and clinical information (4/20). Each AI model demonstrated promise when compared to an embryologist's visual assessment. On average, the models predicted the likelihood of successful clinical pregnancy with greater accuracy than clinical embryologists, signifying greater reliability when compared to human prediction. The AI models performed at a median accuracy of 75.5% (range 59-94%) on predicting embryo morphology grade. The correct prediction (Ground Truth) was defined through the use of embryo images according to post embryologists' assessment following local respective guidelines. Using blind test datasets, the embryologists' accuracy prediction was 65.4% (range 47-75%) with the same ground truth provided by the original local respective assessment. Similarly, AI models had a median accuracy of 77.8% (range 68-90%) in predicting clinical pregnancy through the use of patient clinical treatment information compared to 64% (range 58-76%) when performed by embryologists. When both images/time-lapse and clinical information inputs were combined, the median accuracy by the AI models was higher at 81.5% (range 67-98%), while clinical embryologists had a median accuracy of 51% (range 43-59%).

LIMITATIONS REASONS FOR CAUTION

The findings of this review are based on studies that have not been prospectively evaluated in a clinical setting. Additionally, a fair comparison of all the studies were deemed unfeasible owing to the heterogeneity of the studies, development of the AI models, database employed and the study design and quality.

WIDER IMPLICATIONS OF THE FINDINGS

AI provides considerable promise to the IVF field and embryo selection. However, there needs to be a shift in developers' perception of the clinical outcome from successful implantation towards ongoing pregnancy or live birth. Additionally, existing models focus on locally generated databases and many lack external validation.

STUDY FUNDING/COMPETING INTERESTS

This study was funded by Monash Data Future Institute. All authors have no conflicts of interest to declare.

REGISTRATION NUMBER

CRD42021256333.

ASPRE trial: effects of aspirin on mean arterial blood pressure and uterine artery pulsatility index trajectories in pregnancy

OBJECTIVES

The mechanism by which aspirin prevents pre-eclampsia is poorly understood, and its effects on biomarkers throughout pregnancy are unknown. We aimed to investigate the effects of aspirin on mean arterial pressure (MAP) and mean uterine artery pulsatility index (UtA-PI) using repeated measures from women at increased risk of preterm pre-eclampsia.

METHODS

This was a longitudinal secondary analysis of the Combined Multimarker Screening and Randomized Patient Treatment with Aspirin for Evidence-Based Pre-eclampsia Prevention (ASPRE) trial using repeated measures of MAP and UtA-PI. In the trial, 1620 women at increased risk of preterm pre-eclampsia were identified using the Fetal Medicine Foundation algorithm at 11 + 0 to 13 + 6 weeks, of whom 798 were randomly assigned to receive 150 mg/day aspirin and 822 were assigned to receive placebo daily from 11-14 weeks to 36 weeks of gestation or delivery, whichever came first. MAP and UtA-PI were measured at baseline and follow-up visits at 19-24, 32-34 and 36 weeks of gestation. Generalized additive mixed models with treatment by gestational age interaction terms were used to investigate the effects of aspirin on MAP and UtA-PI trajectories over time.

RESULTS

Among 798 participants in the aspirin group and 822 in the placebo group, there were 5951 MAP and 5942 UtA-PI measurements. Trajectories of raw and multiples of the median (MoM) values of MAP did not differ significantly between the two groups (MAP MoM analysis: P-value for treatment by gestational age interaction, 0.340). In contrast, trajectories of raw and MoM values of UtA-PI showed a significantly steeper decline in the aspirin group than in the placebo group, with the difference mainly driven by a more pronounced reduction before 20 weeks of gestation (UtA-PI MoM analysis: P-value for treatment by gestational age interaction, 0.006).

CONCLUSIONS

In women at increased risk of preterm pre-eclampsia, 150 mg/day aspirin initiated in the first trimester does not affect MAP but is associated with a significant decrease in mean UtA-PI, particularly before 20 weeks of gestation. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Role of placental, fetal and maternal cardiovascular markers in predicting adverse outcome in women with suspected or confirmed pre-eclampsia

OBJECTIVE

To assess the performance of placental, fetal and maternal cardiovascular markers in the prediction of adverse perinatal and maternal outcomes in women with suspected or confirmed pre-eclampsia.

METHODS

This was a prospective prognostic accuracy study of women with suspected or confirmed pre-eclampsia who underwent a series of investigations to measure maternal hemodynamic indices, mean arterial pressure, augmentation index, ophthalmic artery peak systolic velocity (PSV) ratio, uterine artery pulsatility index (UtA-PI), fetal biometric and Doppler parameters, soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF). The performance of these markers, individually or in combination, in predicting adverse perinatal and maternal outcomes was then assessed using receiver-operating-characteristics (ROC)-curve analysis. Adverse maternal outcome was defined as one or more of severe hypertension, admission to the intensive care unit, eclampsia, placental abruption, HELLP syndrome, disseminated intravascular coagulation, platelets < 100 × 10⁹ /L, creatinine > 90 μmol/L and alanine aminotransferase > 100 U/L. Adverse perinatal outcome was defined as one or more of preterm birth at or before 34 + 0 weeks, neonatal intensive care unit admission for > 48 h, respiratory distress syndrome, intraventricular hemorrhage, hypoxic ischemic encephalopathy, necrotizing enterocolitis, retinopathy of prematurity and confirmed fetal infection.

RESULTS

We recruited 126 women with suspected (n = 31) or confirmed (n = 95) pre-eclampsia at a median gestational age of 33.9 weeks (interquartile range, 30.9-36.3 weeks). Pregnancies with adverse perinatal outcome compared to those without had a higher median UtA-PI (1.3 vs 0.8; P < 0.001), ophthalmic artery PSV ratio (0.8 vs 0.7; P = 0.01) and umbilical artery PI percentile (82.0 vs 68.5; P < 0.01) and lower median estimated fetal weight percentile (4.0 vs 43.0; P < 0.001), abdominal circumference percentile (4.0 vs 63.0; P < 0.001), middle cerebral artery PI percentile (28.0 vs 58.5; P < 0.001) and cerebroplacental ratio percentile (18.0 vs 46.5; P < 0.001). Pregnancies with adverse perinatal outcome also had a higher median sFlt-1 (8208.0 pg/mL vs 4508.0 pg/mL; P < 0.001), lower PlGF (27.2 pg/mL vs 76.3 pg/mL; P < 0.001) and a higher sFlt-1/PlGF ratio (445.4 vs 74.4; P < 0.001). The best performing individual marker for predicting adverse perinatal outcome was the sFlt-1/PlGF ratio (area under the ROC curve (AUC), 0.87 (95% CI, 0.81-0.93)), followed by estimated fetal weight (AUC, 0.81 (95% CI, 0.73-0.89)). Women who experienced adverse maternal outcome had a higher median sFlt-1 level (7471.0 pg/mL vs 5131.0 pg/mL; P < 0.001) and sFlt-1/PlGF ratio (204.3 vs 93.3; P < 0.001) and a lower PlGF level (37.0 pg/mL vs 66.1 pg/mL; P = 0.01) and estimated fetal weight percentile (16.5 vs 37.0; P = 0.04). All markers performed poorly in predicting adverse maternal outcome, with sFlt-1 (AUC, 0.69 (95% CI, 0.60-0.79)) and sFlt-1/PlGF ratio (AUC, 0.69 (95% CI, 0.59-0.78)) demonstrating the best individual performance. The addition of cardiovascular, fetal or other placental indices to the sFlt-1/PlGF ratio did not improve the prediction of adverse maternal or perinatal outcomes.

CONCLUSIONS

The sFlt-1/PlGF ratio performs well in predicting adverse perinatal outcomes but is a poor predictor of adverse maternal outcomes in women with suspected or diagnosed pre-eclampsia. The addition of cardiovascular or fetal indices to the model is unlikely to improve the prognostic performance of the sFlt-1/PlGF ratio. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Influence of fibroids on cell-free DNA screening accuracy

OBJECTIVE

Cell-free DNA (cfDNA) screening assesses both maternal and placental cfDNA. Fibroids are common and release cfDNA into maternal serum. Genetic abnormality is seen in 50% of fibroids. We aimed to assess the impact of fibroids on the accuracy of genome-wide cfDNA screening.

METHODS

This was a prospective cohort study of singleton pregnancies examined at one of two centers in Melbourne and Sydney, Australia, between 1 November 2019 and 31 December 2020. All cases underwent pretest ultrasound examination to confirm an ongoing pregnancy of at least 10 weeks' gestation, and, at this stage, the number and volume of any uterine fibroid were documented. Genome-wide cfDNA screening was performed to detect all copy-number variants (CNV) > 7 megabases. The incidence of a false-positive result was compared between cases with and those without fibroids.

RESULTS

Over the 14-month study period, 13 184 patients underwent cfDNA screening, of whom 1017 (7.7%) had fibroids. Fibroids were not identified in any of the 17 participants who had a false-positive result for chromosomes 13, 18, 21, X or Y. Ninety-five (0.7%) cases were screen-positive for subchromosomal aberration (SA), rare autosomal trisomy (RAT) or multiple abnormalities (MA), with 10 of these cases having a fetal genetic abnormality. The incidence of a false-positive RAT, MA or SA result was significantly higher in participants with fibroids (20/1017 (2.0%)) than in those without fibroids (64/12 167 (0.5%)). Women with fibroids were approximately six times as likely to have a false-positive result for SA, and this was associated positively with both fibroid number and volume.

CONCLUSIONS

Most women with fibroids do not have an abnormal result on genome-wide cfDNA screening. However, CNVs due to fibroids are associated with false-positive SA findings, although fibroids do not appear to influence cfDNA screening accuracy for the common autosomal trisomies or sex-chromosomal abnormalities. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Impact of COVID-19 pandemic restrictions on pregnancy duration and outcome in Melbourne, Australia

OBJECTIVE

To investigate the effect of restriction measures implemented to mitigate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission during the coronavirus disease 2019 (COVID-19) pandemic on pregnancy duration and outcome.

METHODS

A before-and-after study was conducted with cohort sampling in three maternity hospitals in Melbourne, Australia, including women who were pregnant when restriction measures were in place during the COVID-19 pandemic (estimated conception date between 1 November 2019 and 29 February 2020) and women who were pregnant before the restrictions (estimated conception date between 1 November 2018 and 28 February 2019). The primary outcome was delivery before 34 weeks' gestation or stillbirth. The main secondary outcome was a composite of adverse perinatal outcomes. Pregnancy outcomes were compared between women exposed to restriction measures and unexposed controls using the χ-square test and modified Poisson regression models, and duration of pregnancy was compared between the groups using survival analysis.

RESULTS

In total, 3150 women who were exposed to restriction measures during pregnancy and 3175 unexposed controls were included. Preterm birth before 34 weeks or stillbirth occurred in 95 (3.0%) exposed pregnancies and in 130 (4.1%) controls (risk ratio (RR), 0.74 (95% CI, 0.57-0.96); P = 0.021). Preterm birth before 34 weeks occurred in 2.4% of women in the exposed group and in 3.4% of women in the control group (RR, 0.71 (95% CI, 0.53-0.95); P = 0.022), without evidence of an increase in the rate of stillbirth in the exposed group (0.7% vs 0.9%; RR, 0.83 (95% CI, 0.48-1.44); P = 0.515). Competing-risks regression analysis showed that the effect of the restriction measures on spontaneous preterm birth was stronger and started earlier (subdistribution hazard ratio (HR), 0.81 (95% CI, 0.64-1.03); P = 0.087) than the effect on medically indicated preterm birth (subdistribution HR, 0.89 (95% CI, 0.70-1.12); P = 0.305). The effect was stronger in women with a previous preterm birth (RR, 0.42 (95% CI, 0.21-0.82); P = 0.008) than in parous women without a previous preterm birth (RR, 0.93 (95% CI, 0.63-1.38); P = 0.714) (P for interaction = 0.044). Composite adverse perinatal outcome was less frequent in the exposed group than in controls (all women: 2.1% vs 2.9%; RR, 0.73 (95% CI, 0.54-0.99); P = 0.042); women with a previous preterm birth: 4.5% vs 8.4%; RR, 0.54 (95% CI, 0.25-1.18); P = 0.116).

CONCLUSIONS

Restriction measures implemented to mitigate SARS-CoV-2 transmission during the COVID-19 pandemic were associated with a reduced rate of preterm birth before 34 weeks. This reduction was mainly due to a lower rate of spontaneous prematurity. The effect was more substantial in women with a previous preterm birth and was not associated with an increased stillbirth rate. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

ASPRE trial: risk factors for development of preterm pre-eclampsia despite aspirin prophylaxis

OBJECTIVE

To examine the possible risk factors amongst maternal characteristics, medical and obstetric history, pre-eclampsia (PE)-specific biomarkers and estimated-risk group, according to The Fetal Medicine Foundation (FMF) algorithm, that are associated with the development of preterm PE with delivery at < 37 weeks' gestation despite aspirin prophylaxis.

METHODS

This was a secondary analysis of data from the ASPRE trial. The study population consisted of women with singleton pregnancy who were deemed to be at high risk for preterm PE, based on the FMF algorithm that combines maternal factors, mean arterial pressure, uterine artery pulsatility index, serum pregnancy-associated plasma protein-A and placental growth factor (PlGF) at 11-13 weeks' gestation. High-risk women were randomized to receive aspirin (150 mg/day) vs placebo from 11-14 until 36 weeks' gestation. The primary outcome was PE with delivery at < 37 weeks' gestation (preterm PE). Multivariate logistic regression analysis was performed to identify independent predictors of preterm PE after adjusting for the use of aspirin and other covariates.

RESULTS

Among 1592 high-risk women, the incidence of preterm PE was 3.0% (n = 48). The interaction between aspirin usage and history of chronic hypertension was significant in the prediction of preterm PE (P = 0.042), which indicated that there was no treatment effect in high-risk women who had chronic hypertension compared with those who did not. Adjusting for aspirin use, the interaction between aspirin and chronic hypertension and other covariates, independent predictors for the development of preterm PE were PlGF multiples of the median (MoM) (adjusted odds ratio (aOR), 0.226 (95% CI, 0.070-0.723)) and estimated-risk group based on the FMF algorithm. Compared to women with an estimated risk of 1 in 51 to 1 in 100, those with an estimated risk of 1 in 2 to 1 in 10 had a 7-fold higher risk of developing preterm PE (aOR, 6.706 (95% CI, 2.381-18.883)), and those with an estimated risk of 1 in 11 to 1 in 50 had a 3-fold higher risk of preterm PE (aOR, 2.769 (95% CI, 1.105-6.939)). PlGF MoM was an independent predictor for preterm PE among women with an estimated risk of 1 in 2 to 1 in 10 (aOR, 0.055 (95% CI, 0.005-0.668)). Among women with an estimated risk of 1 in 11 to 1 in 100, the use of aspirin was an independent predictor of preterm PE (aOR, 0.276 (95% CI, 0.111-0.689)). The cut-off for PlGF with the best performance for the prediction of preterm PE was 0.712 MoM, with an aOR of 3.677 (95% CI, 1.526-8.862).

CONCLUSION

In pregnancies at high risk of preterm PE identified by screening at 11-13 weeks' gestation using the FMF algorithm, a very high-risk result (estimated risk ≥ 1 in 50), compared to an estimated risk of 1 in 51 to 1 in 100, chronic hypertension, compared to no chronic hypertension, and low PlGF concentration (< 0.712 MoM), compared to PlGF ≥ 0.712 MoM, were associated with the development of preterm PE despite aspirin prophylaxis. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Stillbirth: are we making more progress than we think? A retrospective cohort study

OBJECTIVE

To quantify how the changing stillbirth risk profile of women is affecting the interpretation of the stillbirth rate.

DESIGN

A retrospective, population-based cohort study from 1983 to 2018.

SETTING

Victoria, Australia.

POPULATION

A total of 2 419 923 births at ≥28 weeks of gestation.

METHODS

Changes in maternal characteristics over time were assessed. A multivariable logistic regression model was developed for stillbirth, based on maternal characteristics in 1983-1987, and used to calculate individual predictive probabilities of stillbirth from the regression equation. The number of expected stillbirths per year as a result of the change in maternal demographics was then calculated, assuming no changes in care and in the associations between maternal characteristics and stillbirth over time.

MAIN OUTCOME MEASURE

Stillbirth.

RESULTS

Compared with 1983-1987, there were more women in older age groups giving birth, more nulliparous women, more indigenous women and women born in Oceania, Asia and Africa, more multiple pregnancies and more women with pre-existing diabetes in 2014-2018. Despite this, the rate of stillbirth fell from 5.42 per 1000 births in 1983 to 1.72 per 1000 births in 2018 (P < 0.001). Applying the multivariable logistic regression equation, derived from the 1983-87 data, to each year, had there been no changes in care or in the associations between maternal characteristics and stillbirth, the rate of stillbirth would have increased by 12%, from 4.94 per 1000 in 1983 to 5.54 per 1000 in 2018, as a result of the change in maternal characteristics.

CONCLUSIONS

Population rates of stillbirth are falling faster than is generally appreciated.

TWEETABLE ABSTRACT

Population reductions in stillbirth have been underestimated as a result of changing maternal characteristics.

Second- and third-trimester serum levels of growth-differentiation factor-15 in prediction of pre-eclampsia

OBJECTIVE

Pre-eclampsia (PE) is a significant contributor to adverse maternal and perinatal outcome; however, accurate prediction and early diagnosis of this condition remain a challenge. The aim of this study was to compare serum levels of growth-differentiation factor-15 (GDF-15) at three different gestational ages between asymptomatic women who subsequently developed preterm or term PE and healthy controls.

METHODS

This was a case-control study drawn from a prospective observational study on adverse pregnancy outcomes in women attending for their routine second- and third-trimester hospital visits. Serum GDF-15 was determined in 300 samples using a commercial GDF-15 enzyme-linked immunosorbent assay: 120 samples at 19-24 weeks of gestation, 120 samples at 30-34 weeks and 60 samples at 35-37 weeks. Multiple linear regression was applied to logarithmically transformed GDF-15 control values to evaluate the influence of gestational age at blood sampling and maternal characteristics on GDF-15 results. GDF-15 multiples of the normal median (MoM) values, adjusted for gestational age and maternal characteristics, were compared between pregnancies that subsequently developed preterm or term PE and healthy controls.

RESULTS

Values of GDF-15 increased with gestational age. There were no significant differences in GDF-15 MoM values between cases of preterm or term PE and normotensive pregnancies at 19-24 or 35-37 weeks of gestation. At 30-34 weeks, GDF-15 MoM values were significantly increased in cases of preterm PE, but not in those who later developed term PE. Elevated GDF-15 MoM values were associated significantly with a shorter interval between sampling at 30-34 weeks and delivery with PE (P = 0.005).

CONCLUSION

Serum GDF-15 levels at 19-24 or 35-37 weeks of gestation are not predictive of preterm or term PE. At 30-34 weeks, GDF-15 levels are higher in women who subsequently develop preterm PE; however, this difference is small and GDF-15 is unlikely to be useful in clinical practice when used in isolation. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Quality assessment of uterine artery Doppler measurement in first-trimester combined screening for pre-eclampsia

OBJECTIVE

To assess the quality of mean uterine artery (UtA) pulsatility index (PI) measurement in a first-trimester pre-eclampsia screening program.

METHODS

Consecutive women with a singleton pregnancy attending first-trimester screening for fetal chromosomal abnormalities also had combined screening for pre-eclampsia based on the Fetal Medicine Foundation (FMF) algorithm, at a large practice in Sydney, Australia, from May 2014 to February 2017. Distributions of mean UtA-PI multiples of the median (MoM) on a logarithmic scale were plotted in relation to the normal median with 95% CI for each operator and for each month. Central tendency and dispersion and cumulative sum charts were produced. Mean UtA-PI MoM values between 0.95 and 1.05 were considered ideal and those between 0.90 and 1.10 were considered acceptable. The screen-positive rates for preterm pre-eclampsia in different groups of sonographers according to their mean log₁₀ UtA-PI MoM were calculated and compared using the chi-square test.

RESULTS

A total of 21 010 women attended for first-trimester ultrasound and had screening for pre-eclampsia. The overall median UtA-PI MoM was 1.042 (interquartile range (IQR), 0.85-1.26). Of 46 sonographers, 42 (91.3%) performed more than 50 examinations and, of those, 41 (97.6%) measured UtA-PI within the acceptable range. Sonographers measuring UtA-PI MoM on average below 0.95 and those measuring it above 1.05 had, respectively, lower and higher screen-positive rates when compared with those with measurements within the 0.95-1.05 UtA-PI MoM interval (7.2% and 13.2% vs 11.2%, respectively, P < 0.001).

CONCLUSION

UtA Doppler is measured well among trained operators when following an established protocol. While slight variations are expected, systematic error in this measurement impacts on the screen-positive rate. Therefore, a quality control process should be in place and retraining of staff may be required. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Association between fetal fraction on cell-free DNA testing and first-trimester markers for pre-eclampsia

OBJECTIVES

To evaluate the association between fetal fraction on cell-free DNA (cfDNA) testing and first-trimester markers for pre-eclampsia, and to investigate the possible association of low fetal fraction with increased risks for pre-eclampsia (PE) and fetal growth restriction (FGR).

METHODS

This was a retrospective cohort study including all women with a singleton pregnancy who had risk calculation for PE and FGR between 11 + 0 and 13 + 6 weeks' gestation and who also had cfDNA as a primary or secondary screening test for chromosomal abnormalities at any gestational age at two fetal medicine clinics in Sydney and Melbourne, Australia, between March 2013 and May 2017. Logarithmically transformed fetal fraction results were adjusted for gestational age and maternal characteristics. Associations with mean arterial pressure (MAP), mean uterine artery pulsatility index (UtA-PI), pregnancy-associated plasma protein A (PAPP-A), placental growth factor (PlGF), and risks for PE < 34 weeks, PE < 37 weeks and FGR < 37 weeks were analyzed using correlation analysis and univariable and multivariable linear regressions.

RESULTS

In total, 4317 singleton pregnancies that underwent cfDNA testing with fetal fraction reported were included. Significant prediction of fetal fraction was provided by gestational age, conception by in-vitro fertilization, maternal age, body mass index, chronic hypertension, diabetes mellitus, South Asian ethnicity and being parous without history of PE or FGR. Fetal fraction was associated inversely with MAP and UtA-PI and associated positively with PAPP-A and PlGF. The lower the fetal fraction, the higher were the risks for PE < 34 weeks, PE < 37 weeks and FGR < 37 weeks (P < 0.001 for all).

CONCLUSIONS

There is a significant association between fetal fraction result and first-trimester markers for adverse pregnancy outcome. Low fetal fraction is associated with an increased risk for pregnancy complication, but its capacity to act an as independent first-trimester marker in an algorithm for screening for PE and FGR requires further research. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Screening for pre-eclampsia by maternal factors and biomarkers at 11-13 weeks' gestation

OBJECTIVE

To examine the performance of screening for early, preterm and term pre-eclampsia (PE) at 11-13 weeks' gestation by maternal factors and combinations of mean arterial pressure (MAP), uterine artery (UtA) pulsatility index (PI), serum placental growth factor (PlGF) and serum pregnancy-associated plasma protein-A (PAPP-A).

METHODS

The data for this study were derived from three previously reported prospective non-intervention screening studies at 11 + 0 to 13 + 6 weeks' gestation in a combined total of 61 174 singleton pregnancies, including 1770 (2.9%) that developed PE. Bayes' theorem was used to combine the prior distribution of gestational age at delivery with PE, obtained from maternal characteristics, with various combinations of biomarker multiples of the median (MoM) values to derive patient-specific risks of delivery with PE at < 37 weeks' gestation. The performance of such screening was estimated.

RESULTS

In pregnancies that developed PE, compared to those without PE, the MoM values of UtA-PI and MAP were increased and those of PAPP-A and PlGF were decreased, and the deviation from normal was greater for early than late PE for all four biomarkers. Combined screening by maternal factors, UtA-PI, MAP and PlGF predicted 90% of early PE, 75% of preterm PE and 41% of term PE, at a screen-positive rate of 10%; inclusion of PAPP-A did not improve the performance of screening. The performance of screening depended on the racial origin of the women; on screening by a combination of maternal factors, MAP, UtA-PI and PlGF and using a risk cut-off of 1 in 100 for PE at < 37 weeks in Caucasian women, the screen-positive rate was 10% and detection rates for early, preterm and term PE were 88%, 69% and 40%, respectively. With the same method of screening and risk cut-off in women of Afro-Caribbean racial origin, the screen-positive rate was 34% and detection rates for early, preterm and term PE were 100%, 92% and 75%, respectively.

CONCLUSION

Screening by maternal factors and biomarkers at 11-13 weeks' gestation can identify a high proportion of pregnancies that develop early and preterm PE. © 2018 Crown copyright. Ultrasound in Obstetrics & Gynecology © 2018 ISUOG.

Prediction and prevention of small-for-gestational-age neonates: evidence from SPREE and ASPRE

OBJECTIVES

To examine the effect of first-trimester screening for pre-eclampsia (PE) on the prediction of delivering a small-for-gestational-age (SGA) neonate and the effect of prophylactic use of aspirin on the prevention of SGA.

METHODS

The data for this study were derived from two multicenter studies. In SPREE, we investigated the performance of screening for PE by a combination of maternal characteristics and biomarkers at 11-13 weeks' gestation. In ASPRE, women with a singleton pregnancy identified by combined screening as being at high risk for preterm PE (> 1 in 100) participated in a trial of aspirin (150 mg/day from 11-14 until 36 weeks' gestation) compared to placebo. In this study, we used the data from the ASPRE trial to estimate the effect of aspirin on the incidence of SGA with birth weight < 10^th , < 5^th and < 3^rd percentile for gestational age. We also used the data from SPREE to estimate the proportion of SGA in the pregnancies with a risk for preterm PE of > 1 in 100.

RESULTS

In SPREE, screening for preterm PE by a combination of maternal factors, mean arterial pressure, uterine artery pulsatility index and serum placental growth factor identified a high-risk group that contained about 46% of SGA neonates < 10^th percentile born at < 37 weeks' gestation (preterm) and 56% of those born at < 32 weeks (early); the overall screen-positive rate was 12.2% (2014 of 16 451 pregnancies). In the ASPRE trial, use of aspirin reduced the overall incidence of SGA < 10^th percentile by about 40% in babies born at < 37 weeks' gestation and by about 70% in babies born at < 32 weeks; in babies born at ≥ 37 weeks, aspirin did not have a significant effect on incidence of SGA. The aspirin-related decrease in incidence of SGA was mainly due to its incidence decreasing in pregnancies with PE, for which the decrease was about 70% in babies born at < 37 weeks' gestation and about 90% in babies born at < 32 weeks. On the basis of these results, it was estimated that first-trimester screening for preterm PE and use of aspirin in the high-risk group would potentially reduce the incidence of preterm and early SGA by about 20% and 40%, respectively.

CONCLUSION

First-trimester screening for PE by the combined test identifies a high proportion of cases of preterm SGA that can be prevented by the prophylactic use of aspirin. © 2018 Crown copyright. Ultrasound in Obstetrics & Gynecology © 2018 ISUOG.

ASPRE trial: incidence of preterm pre-eclampsia in patients fulfilling ACOG and NICE criteria according to risk by FMF algorithm

OBJECTIVE

To report the incidence of preterm pre-eclampsia (PE) in women who are screen positive according to the criteria of the National Institute for Health and Care Excellence (NICE) and the American College of Obstetricians and Gynecologists (ACOG), and compare the incidence with that in those who are screen positive or screen negative by The Fetal Medicine Foundation (FMF) algorithm.

METHODS

This was a secondary analysis of data from the ASPRE study. The study population consisted of women with singleton pregnancy who underwent prospective screening for preterm PE by means of the FMF algorithm, which combines maternal factors and biomarkers at 11-13 weeks' gestation. The incidence of preterm PE in women fulfilling the NICE and ACOG criteria was estimated; in these patients the incidence of preterm PE was then calculated in those who were screen negative relative to those who were screen positive by the FMF algorithm.

RESULTS

A total of 34 573 women with singleton pregnancy delivering at ≥ 24 weeks' gestation underwent prospective screening for preterm PE, of which 239 (0.7%) cases developed preterm PE. At least one of the ACOG criteria was fulfilled in 22 287 (64.5%) pregnancies and the incidence of preterm PE was 0.97% (95% CI, 0.85-1.11%); in the subgroup that was screen positive by the FMF algorithm the incidence of preterm PE was 4.80% (95% CI, 4.14-5.55%), and in those that were screen negative it was 0.25% (95% CI, 0.18-0.33%), with a relative incidence in FMF screen negative to FMF screen positive of 0.051 (95% CI, 0.037-0.071). In 1392 (4.0%) pregnancies, at least one of the NICE high-risk criteria was fulfilled, and in this group the incidence of preterm PE was 5.17% (95% CI, 4.13-6.46%); in the subgroups of screen positive and screen negative by the FMF algorithm, the incidence of preterm PE was 8.71% (95% CI, 6.93-10.89%) and 0.65% (95% CI, 0.25-1.67%), respectively, and the relative incidence was 0.075 (95% CI, 0.028-0.205). In 2360 (6.8%) pregnancies fulfilling at least two of the NICE moderate-risk criteria, the incidence of preterm PE was 1.74% (95% CI, 1.28-2.35%); in the subgroups of screen positive and screen negative by the FMF algorithm the incidence was 4.91% (95% CI, 3.54-6.79%) and 0.42% (95% CI, 0.20-0.86%), respectively, and the relative incidence was 0.085 (95% CI, 0.038-0.192).

CONCLUSION

In women who are screen positive for preterm PE by the ACOG or NICE criteria but screen negative by the FMF algorithm, the risk of preterm PE is reduced to within or below background levels. The results provide further evidence to support the personalized risk-based screening method that combines maternal factors and biomarkers. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

ASPRE trial: performance of screening for preterm pre-eclampsia

OBJECTIVE

To examine the performance of screening for preterm and term pre-eclampsia (PE) in the study population participating in the ASPRE (Combined Multimarker Screening and Randomized Patient Treatment with Aspirin for Evidence-Based Preeclampsia Prevention) trial.

METHODS

This was a prospective first-trimester multicenter study on screening for preterm PE in 26 941 singleton pregnancies by means of an algorithm that combines maternal factors, mean arterial pressure, uterine artery pulsatility index and maternal serum pregnancy-associated plasma protein-A and placental growth factor at 11-13 weeks' gestation. Eligible women with an estimated risk for preterm PE of > 1 in 100 were invited to participate in a double-blind trial of aspirin (150 mg per day) vs placebo from 11-14 until 36 weeks' gestation, which showed that, in the aspirin group, the incidence of preterm PE was reduced by 62%. In the screened population, the detection rates (DRs) and false-positive rates (FPRs) for delivery with PE < 37 and ≥ 37 weeks were estimated after adjustment for the effect of aspirin in those receiving this treatment. We excluded 1144 (4.2%) pregnancies because of loss to follow-up or study withdrawal (n = 716), miscarriage (n = 243) or termination (n = 185).

RESULTS

The study population of 25 797 pregnancies included 180 (0.7%) cases of preterm PE, 450 (1.7%) of term PE and 25 167 (97.6%) without PE. In combined first-trimester screening for preterm PE with a risk cut-off of 1 in 100, the DR was 76.7% (138/180) for preterm PE and 43.1% (194/450) for term PE, at screen-positive rate of 10.5% (2707/25 797) and FPR of 9.2% (2375/25 797).

CONCLUSION

The performance of screening in the ASPRE study was comparable with that of a study of approximately 60 000 singleton pregnancies used for development of the algorithm; in that study, combined screening detected 76.6% of cases of preterm PE and 38.3% of term PE at a FPR of 10%. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Accuracy of competing-risks model in screening for pre-eclampsia by maternal factors and biomarkers at 11-13 weeks' gestation

OBJECTIVE

To examine the diagnostic accuracy of a previously developed model for prediction of pre-eclampsia (PE) by a combination of maternal factors and biomarkers at 11-13 weeks' gestation.

METHODS

This was a prospective first-trimester multicenter study of screening for PE in 8775 singleton pregnancies. A previously published algorithm was used for the calculation of patient-specific risk of PE in each individual. The detection rates (DRs) and false-positive rates (FPRs) for delivery with PE < 32, < 37 and ≥ 37 weeks were estimated and compared with those for the dataset used for development of the algorithm.

RESULTS

In the study population, 239 (2.7%) cases developed PE, of which 17 (0.2%), 59 (0.7%) and 180 (2.1%) developed PE < 32, < 37 and ≥ 37 weeks, respectively. With combined screening by maternal factors, mean arterial pressure, uterine artery pulsatility index and serum placental growth factor, the DR was 100% (95% CI, 80-100%) for PE < 32 weeks, 75% (95% CI, 62-85%) for PE < 37 weeks and 43% (95% CI, 35-50%) for PE ≥ 37 weeks, at a 10% FPR. These DRs were similar to the estimated rates for the dataset used for development of the model: 89% (95% CI, 79-96%) for PE < 32 weeks, 75% (95% CI, 70-80%) for PE < 37 weeks and 47% (95% CI, 44-51%) for PE ≥ 37 weeks.

CONCLUSION

Assessment of a combination of maternal factors and biomarkers at 11-13 weeks provides effective first-trimester screening for preterm PE. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Multicenter screening for pre-eclampsia by maternal factors and biomarkers at 11-13 weeks' gestation: comparison with NICE guidelines and ACOG recommendations

OBJECTIVE

To compare the performance of screening for pre-eclampsia (PE) based on risk factors from medical history, as recommended by NICE and ACOG, with the method proposed by The Fetal Medicine Foundation (FMF), which uses Bayes' theorem to combine the a-priori risk from maternal factors, derived by a multivariable logistic model, with the results of various combinations of biophysical and biochemical measurements.

METHODS

This was a prospective multicenter study of screening for PE in 8775 singleton pregnancies at 11-13 weeks' gestation. A previously published FMF algorithm was used for the calculation of patient-specific risk of PE in each individual. The detection rates (DRs) and false-positive rates (FPRs) for delivery with PE < 32, < 37 and ≥ 37 weeks were estimated and compared with those derived from application of NICE guidelines and ACOG recommendations. According to NICE, all high-risk pregnancies should be offered low-dose aspirin. According to ACOG, use of aspirin should be reserved for women with a history of PE in at least two previous pregnancies or PE requiring delivery < 34 weeks' gestation.

RESULTS

In the study population, 239 (2.7%) cases developed PE, of which 17 (0.2%), 59 (0.7%) and 180 (2.1%) developed PE < 32, < 37 and ≥ 37 weeks, respectively. Screening with use of the FMF algorithm based on a combination of maternal factors, mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF) detected 100% (95% CI, 80-100%) of PE < 32 weeks, 75% (95% CI, 62-85%) of PE < 37 weeks and 43% (95% CI, 35-50%) of PE ≥ 37 weeks, at a 10.0% FPR. Screening with use of NICE guidelines detected 41% (95% CI, 18-67%) of PE < 32 weeks, 39% (95% CI, 27-53%) of PE < 37 weeks and 34% (95% CI, 27-41%) of PE ≥ 37 weeks, at 10.2% FPR. Screening with use of ACOG recommendations detected 94% (95% CI, 71-100%) of PE < 32 weeks, 90% (95% CI, 79-96%) of PE < 37 weeks and 89% (95% CI, 84-94%) of PE ≥ 37 weeks, at 64.2% FPR. Screening based on the ACOG recommendations for use of aspirin detected 6% (95% CI, 1-27%) of PE < 32 weeks, 5% (95% CI, 2-14%) of PE < 37 weeks and 2% (95% CI, 0.3-5%) of PE ≥ 37 weeks, at 0.2% FPR.

CONCLUSION

Performance of screening for PE at 11-13 weeks' gestation by the FMF algorithm using a combination of maternal factors, MAP, UtA-PI and PlGF, is by far superior to the methods recommended by NICE and ACOG. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Maternal plasma cell-free DNA in the prediction of pre-eclampsia

OBJECTIVES

To examine whether maternal plasma concentrations of total cell-free (cf)DNA and fetal fraction at 11-13 and 20-24 weeks' gestation in pregnancies that subsequently develop pre-eclampsia (PE) are different from those without this complication.

METHODS

Total cfDNA and fetal fraction were measured in 20 cases of early PE requiring delivery at < 34 weeks, in 20 cases of late PE with delivery at ≥ 34 weeks and in 200 normotensive controls, at 11-13 and 20-24 weeks' gestation. Total cfDNA and fetal fraction measured at 11-13 weeks were converted to multiples of the median (MoM), corrected for maternal characteristics and gestational age. The distributions of total cfDNA and fetal fraction at 20-24 weeks were expressed as MoM of values at 11-13 weeks. The Mann-Whitney U-test was used to determine the significance of differences in the median values in each outcome group relative to that in the controls.

RESULTS

In the early-PE group at 11-13 weeks, compared with controls, there was a significant increase in median total cfDNA (2104 genome equivalents (GE)/mL vs 1590 GE/mL) and a decrease in median fetal fraction (6.8% vs 8.7%). In the late-PE group at 20-24 weeks, compared with controls, there was a significant decrease in median fetal fraction (8.2% vs 9.6%). These significant differences between groups were not observed when the values were converted to MoM.

CONCLUSION

Measurements of total cfDNA and fetal fraction in maternal plasma at 11-13 and 20-24 weeks are not predictive of PE.