Antenatal placental assessment in the prediction of adverse pregnancy outcome after reduced fetal movement

The predictive value of thromboelastography, routine blood indices, ultrasound parameters, and placental thickness in determining fetal outcome

OBJECTIVE

To evaluate the predictive value of thromboelastography, routine blood indices, ultrasound measurements, and placental thickness for fetal outcome.

METHODS

A retrospective analysis of 218 expectant mothers at our hospital from April 2020 to June 2022 was conducted. Mothers were classified into favorable (n=164) and adverse (n=54) fetal outcome groups. We compared thromboelastography, blood counts, and ultrasound parameters, including placental thickness, between the two groups. Predictive models using lasso regression were developed for individual assessment type and their combinations. Model efficacies were evaluated by ROC curves and Delong's test.

RESULTS

Thromboelastography indicated significantly higher values of R (P=0.004), Angle (P<0.001), and MA (P=0.002) while notably lower K (P<0.001) in the adverse outcome group compared to the favorable outcome group. Peripheral blood analysis showed elevated levels of WBC (P<0.001), CRP (P=0.001), and PLR (P<0.001) in the adverse outcome group. Ultrasound assessments revealed significant increases in S/D (P<0.001), PI (P=0.016), RI (P<0.001), and placental thickness (P<0.001) in the adverse outcome group. The areas under the curve (AUCs) for the thromboelastography (4 features), peripheral blood indices (3 features), ultrasound parameters (4 features), and combined index model (11 features) were 0.774, 0.779, 0.961, and 0.978, respectively. Delong's test indicated that the combined model's AUC did not significantly differ from that of the ultrasound parameters (P>0.05) but was superior to the models based on thromboelastography, peripheral blood indices, and placental thickness alone (P<0.001).

CONCLUSION

This study underscores the unparalleled predictive value of ultrasound metrics in identifying the risk of adverse pregnancy outcomes, highlighting their critical role in prenatal risk assessment and monitoring frameworks.

Decreased fetal movements: Report from the International Stillbirth Alliance conference workshop

Maternal reports of decreased fetal movement (DFM) are a common reason to present to maternity care and are associated with stillbirth and other adverse outcomes. Promoting awareness of fetal movements and prompt assessment of DFM has been recommended to reduce stillbirths. However, evidence to guide clinical management of such presentations is limited. Educational approaches to increasing awareness of fetal movements in pregnant women and maternity care providers with the aim of reducing stillbirths have recently been evaluated in a several large clinical trials internationally. The International Stillbirth Alliance Virtual Conference in Sydney 2021 provided an opportunity for international experts in fetal movements to share reports on the findings of fetal movement awareness trials, consider evidence for biological mechanisms linking DFM and fetal death, appraise approaches to clinical assessment of DFM, and highlight research priorities in this area. Following this workshop summaries of the sessions prepared by the authors provide an overview of understandings of fetal movements in maternity care at the current time and highlights future directions in fetal movement research.

Development of core outcome sets for studies relating to awareness and clinical management of reduced fetal movement

OBJECTIVE

This study aimed to create core outcome sets (COSs) for use in research studies relating to the awareness and clinical management of reduced fetal movement (RFM).

DESIGN

Delphi survey and consensus process.

SETTING

International.

POPULATION

A total of 128 participants (40 parents, 19 researchers and 65 clinicians) from 16 countries.

METHODS

A systematic literature review was conducted to identify outcomes in studies of interventions relating to the awareness and the clinical management of RFM. Using these outcomes as a preliminary list, stakeholders rated the importance of these outcomes for inclusion in COSs for studies of: (i) awareness of RFM; and (ii) clinical management of RFM.

MAIN OUTCOME MEASURES

Preliminary lists of outcomes were discussed at consensus meetings where two COSs (one for studies of RFM awareness and one for studies of clinical management of RFM).

RESULTS

The first round of the Delphi survey was completed by 128 participants, 66% of whom (n = 84) completed all three rounds. Fifty outcomes identified by the systematic review, after multiple definitions were combined, were voted on in round one. Two outcomes were added in round one, and as such 52 outcomes were voted on in two lists in rounds two and three. The COSs for studies of RFM awareness and clinical management are comprised of eight outcomes (four maternal and four neonatal) and 10 outcomes (two maternal and eight neonatal), respectively.

CONCLUSIONS

These COSs provide researchers with the minimum set of outcomes to be measured and reported in studies relating to the awareness and the clinical management of RFM.

Should we use composite outcomes in obstetric clinical prediction models?

Clinical prediction models assist clinicians to estimate the natural course of a condition, and thus facilitate treatment decisions. The development of prediction models is increasingly common in obstetric research. Composite outcomes, whereby multiple outcomes are combined into a single endpoint, are frequently used in obstetric prediction models to increase statistical power when predicting rare events. Although existing literature has reviewed the positives and negatives of using composite outcomes in clinical trials, there has been minimal commentary on the implications of their use in the development and reporting of prognostic models. In this article, we review these issues, in particular, highlighting how unequal individual relationships between predictors and individual component outcomes can result in misleading conclusions, which may result in the omission of important but rare predictors or inappropriately inform clinical decisions to implement an intervention. We propose careful use, or where possible avoidance, of composite outcomes in the development of prognostic models in obstetrics. Methodological standards for developing prognostic models should be updated to standardise and appraise composite outcomes when their use is necessary. We also support previous recommendations to report on the accuracy of key components and inconsistencies among predictor variables.

Intraplacental Villous Artery Doppler can Improve the Ability to Predict Placenta-Mediated Disease

OBJECTIVE

Evaluation of Intraplacental Villous Artery Doppler (IPVA) as a predictive factor compared to umbilical artery (UA) Doppler in placenta-mediated disease (PMD).

METHODS

This prospective study included a group of 106 pregnant women, of which 76 patients constituted the PMD group: preeclampsia (PE) and small for gestational age (SGA), and 30 pregnant women constituted the control group. IPVA and UA Doppler evaluation was performed in 2 pregnancy periods: 20.0-23.6 weeks, and 28.0-32.6 weeks of gestation.

RESULTS

From the study of maternal characteristics and risk factors for the presented pathology, we found that no studied risk factor was statistically involved in the evolution toward PMD during pregnancy. In the control group, we noticed a decrease in IPVA PI and RI, along with an increase in gestational age, while in the PMD group, these indices increased. Both in the 2nd and the 3rd trimester, we had a significant statistical difference between the two groups (p<0.001). Regarding the degree of prediction of the changes that occurred at this level, we found a good statistical correlation. A higher degree of positive predictability is noted, for IPVA-PI, but also for UA-PI, but with better sensitivity (72.27%) for UA PI in the 2nd trimester.

CONCLUSIONS

We can conclude that both Doppler measurements, IPVA and UA can be used to evaluate and detect pregnancy complications that belong to PMD, preeclampsia, and/or fetal growth restriction.

Evaluation of the relationship between reduced fetal movement and obstetric-neonatal outcomes and placental pathologies

BACKGROUND

Fetal movements are one of the simple methods that show the baby's well-being. Conditions associated with decreased fetal movements have not been determined, so it is important to analyze their different aspects. This study aimed to evaluate the relationship between reduced fetal movement and obstetric-neonatal outcomes, and placental pathologies.

METHODS

In this prospective controlled study, laboratory results (blood glucose, hemoglobin, thyroid-stimulating hormone [TSH]), a non-stress test (NST), biophysical profile results, obstetric and neonatal outcomes, and placental pathological results of 74 pregnant women at 35 or more gestational weeks (to exclude the effect of prematurity on obstetric and neonatal outcomes) attending the obstetrics clinic between December 26, 2017 and January 30, 2019 with complaints of reduced fetal movement, were compared with 74 healthy pregnant women. Since prematurity and post-maturity may adversely affect obstetric-neonatal and placental pathology results, term pregnancies between 37^0/7-40^6/7 weeks were evaluated separately.

RESULTS

In the group with reduced fetal movement, the biophysical profile was lower than the controls (P=0.013). Among placental pathologies, chorangiosis and hypercoiled cord were significantly higher in the group with reduced fetal movement than controls (P<0.05). Small for gestational age (SGA) and fetal growth restriction (FGR) in this group had these pathologies. Results of women at 37^0/7-40^6/7 weeks were similar except for the additional finding of chorioamnionitis.

CONCLUSIONS

Reduced fetal movement may be associated with the low biophysical profile. In cases where fetal movement decreases, placental chorangiosis and hypercoiled cord seem to be associated with fetal growth restriction.

Analytical Performance and Quality Indicators of Fully Automated Immunoassays for sFlt-1 and PlGF

BACKGROUND

The ratio of the antiangiogenic factor, soluble fms-like tyrosine kinase 1 (sFlt-1), to the proangiogenic factor, placental growth factor (PlGF), is associated with increased risk of preeclampsia. Here, we describe an analytical evaluation of the Elecsys sFlt-1 and PlGF assays at the first North American site in which they were clinically implemented.

METHODS

The analytical evaluation included short- and long-term imprecision, method comparison, accuracy, linearity, sample stability, limit of quantification verification, and measurement uncertainty. Quality indicators were also evaluated, including turnaround time and repeat test frequency.

RESULTS

Short-term (13-day) and long-term (12-month) imprecision for sFlt-1 and PlGF were <4% CV. Method comparison (n = 40) between Roche cobas e602 and e411 exhibited r > 0.99 and bias <10%. sFlt-1/PlGF ratio rule-out cutoffs (≤33 and ≤38) and rule-in cutoffs (>38, >85, and >110) exhibited negative percent agreement and positive percent agreement of 100%, respectively (n = 40). During the first 12 months, 257 orders were placed, repeat test frequency was 17.5%, mean time between repeat orders was 23 days, and 72.0% of results were reported within 2 h from sample receipt when quality control was run continuously.

CONCLUSIONS

We describe analytical performance parameters and quality indicators of the Elecsys sFlt-1 and PlGF assays, which was the first North American clinical laboratory site to implement these assays in support of the institution's high-risk obstetrical unit.

Development of a core outcome set (COS) for studies relating to awareness and clinical management of reduced fetal movement: study protocol

BACKGROUND

Concerns regarding reduced fetal movements (RFM) are reported in 5-15% of pregnancies, and RFM are associated with adverse pregnancy outcomes including fetal growth restriction and stillbirth. Studies have aimed to improve pregnancy outcomes by evaluating interventions to raise awareness of RFM in pregnancy, such as kick counting, evaluating interventions for the clinical management of RFM, or both. However, there is not currently a core outcome set (COS) for studies of RFM. This study aims to create a COS for use in research studies that aim to raise awareness of RFM and/or evaluate interventions for the clinical management of RFM.

METHODS

A systematic review will be conducted, to identify outcomes used in randomised and non-randomised studies with control groups that aimed to raise awareness of RFM (for example by using mindfulness techniques, fetal movement counting, or other tools such as leaflets or mobile phone applications) and/or that evaluated the clinical management of RFM. An international Delphi consensus will then be used whereby stakeholders will rate the importance of the outcomes identified in the systematic review in (i) awareness and (ii) clinical management studies. The preliminary lists of outcomes will be discussed at a consensus meeting where one final COS for awareness and management, or two discrete COS (one for awareness and one for management), will be agreed upon.

DISCUSSION

A well-developed COS will provide researchers with the minimum set of outcomes that should be measured and reported in studies that aim to quantify the effects of interventions.

Sexually dimorphic patterns in maternal circulating microRNAs in pregnancies complicated by fetal growth restriction

Background

Current methods fail to accurately predict women at greatest risk of developing fetal growth restriction (FGR) or related adverse outcomes, including stillbirth. Sexual dimorphism in these adverse pregnancy outcomes is well documented as are sex-specific differences in gene and protein expression in the placenta. Circulating maternal serum microRNAs (miRNAs) offer potential as biomarkers that may also be informative of underlying pathology. We hypothesised that FGR would be associated with an altered miRNA profile and would differ depending on fetal sex.

Methods

miRNA expression profiles were assessed in maternal serum (> 36 weeks’ gestation) from women delivering a severely FGR infant (defined as an individualised birthweight centile (IBC) < 3rd) and matched control participants (AGA; IBC = 20–80th), using miRNA arrays. qPCR was performed using specific miRNA primers in an expanded cohort of patients with IBC < 5th (n = 15 males, n = 16 females/group). Maternal serum human placental lactogen (hPL) was used as a proxy to determine if serum miRNAs were related to placental dysfunction. In silico analyses were performed to predict the potential functions of altered miRNAs.

Results

Initial analyses revealed 11 miRNAs were altered in maternal serum from FGR pregnancies. In silico analyses revealed all 11 altered miRNAs were located in a network of genes that regulate placental function. Subsequent analysis demonstrated four miRNAs showed sexually dimorphic patterns. miR-28-5p was reduced in FGR pregnancies (p < 0.01) only when there was a female offspring and miR-301a-3p was only reduced in FGR pregnancies with a male fetus (p < 0.05). miR-454-3p was decreased in FGR pregnancies (p < 0.05) regardless of fetal sex but was only positively correlated to hPL when the fetus was female. Conversely, miR-29c-3p was correlated to maternal hPL only when the fetus was male. Target genes for sexually dimorphic miRNAs reveal potential functional roles in the placenta including angiogenesis, placental growth, nutrient transport and apoptosis.

Conclusions

These studies have identified sexually dimorphic patterns for miRNAs in maternal serum in FGR. These miRNAs may have potential as non-invasive biomarkers for FGR and associated placental dysfunction. Further studies to determine if these miRNAs have potential functional roles in the placenta may provide greater understanding of the pathogenesis of placental dysfunction and the differing susceptibility of male and female fetuses to adverse in utero conditions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-021-00405-z.

Detection and treatment of pregnancies at high risk of fetal growth restriction (FGR) and stillbirth remains a major obstetric challenge; circulating maternal serum microRNAs (miRNAs) offer potential as novel biomarkers.

Unbiased analysis of serum miRNAs in women in late pregnancy identified a specific profile of circulating miRNAs in women with a growth-restricted infant.

Some altered miRNAs (miR-28-5p, miR-301a-3p) showed sexually dimorphic expression in FGR pregnancies and others a fetal-sex dependent association to a hormonal marker of placental dysfunction (miR-454-3p, miR-29c-3p).

miR-301a-3p and miR-28-5p could potentially be used to predict FGR specifically in pregnancies with a male or female baby, respectively, however larger cohort studies are required.

Further investigations of these miRNAs and their relationship to placental dysfunction will lead to a better understanding of the pathophysiology of FGR and why there is differing susceptibility of male and female fetuses to FGR and stillbirth.

Country of birth, educational level and other predictors of seeking care due to decreased fetal movements: an observational study in Sweden using data from a cluster-randomised controlled trial

OBJECTIVES

To identify predictors of seeking care for decreased fetal movements and assess whether care-seeking behaviour is influenced by Mindfetalness.

DESIGN

Observational study with data from a cluster-randomised controlled trial.

SETTING

67 maternity clinics and 6 obstetrical clinics in Sweden.

PARTICIPANTS

All pregnant women with a singleton pregnancy who contacted the obstetrical clinic due to decreased fetal movements from 32 weeks' gestation of 39 865 women.

METHODS

Data were collected from a cluster-randomised controlled trial where maternity clinics were randomised to Mindfetalness or routine care. Mindfetalness is a self-assessment method for women to use daily to become familiar with the unborn baby's fetal movement pattern.

OUTCOME MEASURES

Predictors for contacting healthcare due to decreased fetal movements.

RESULTS

Overall, 5.2% (n=2059) of women contacted healthcare due to decreased fetal movements, among which 1287 women (62.5%) were registered at a maternity clinic randomised to Mindfetalness and 772 women (37.5%) were randomised to routine care. Predictors for contacting healthcare due to decreased fetal movements were age, country of birth, educational level, parity, prolonged pregnancy and previous psychiatric care (p<0.001). The main differences were seen among women born in Africa as compared with Swedish-born women (2% vs 6%, relative risk (RR) 0.34, 95% CI 0.25 to 0.44) and among women with low educational level compared with women with university-level education (2% vs 5.4%, RR 0.36, 95% CI 0.19 to 0.62). Introducing Mindfetalness in maternity care increased the number of women seeking care due to decreased fetal movements overall.

CONCLUSION

Women with country of birth outside Sweden and low educational level sought care for decreased fetal movements to a lesser extent compared with women born in Sweden and those with university degrees. Future research could explore whether pregnancy outcomes can be improved by motivating women in these groups to contact healthcare if they feel a decreased strength or frequency of fetal movements.

TRIAL REGISTRATION NUMBER

NCT02865759.

Pulsatility effects of flow on vascular tone in the fetoplacental circulation

INTRODUCTION

The regulation of vascular tone in the fetoplacental circulation is governed by endocrine and mechanical forces yielding a relaxed basal state in normal pregnancy. Flow mediated vasodilation, induced by shear stress and endothelial nitric oxide signalling, is key to driving vasorelaxation in this circulation. The pulsatile property of blood flow, as opposed to the flow rate, could provide an additional factor in this regulation, but its effects and signalling have never been explored in the fetoplacental microvasculature.

METHODS

Here, we studied the effects of non-pulsatile and pulsatile flow modalities on vascular resistance in the fetoplacental microcirculation of the human placenta using an ex vivo perfusion model; and examined a potential role for nitric oxide. We also explored whether the placental Doppler velocimetry waveform is sustained within subchorial arteries in vivo.

RESULTS

Pulsatile flow reduced basal impedance to flow during steady state perfusion compared to non-pulsatile flow, signalled through enhanced nitric oxide production. Doppler velocimetry waveforms were visible within the subchorial arteries in vivo.

CONCLUSION

This work suggests that the pulsatile property of flow through the fetoplacental circulation is sensed by the fetoplacental vasculature to mediate a signalling response and provide additional vasodilation of this microcirculation. We speculate that in pregnancy disease, altered amplitude and frequency of the subchorial pulse might impact on vascular function in a compromised high-resistance placental microcirculation.

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

INTRODUCTION

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Increased placental macrophages and a pro-inflammatory profile in placentas and maternal serum in infants with a decreased growth rate in the third trimester of pregnancy

PROBLEM

There is growing evidence for the role of placental inflammation in the pathophysiology of pregnancy complications including fetal growth restriction (FGR). This study aimed to characterize the inflammatory profile in the maternal circulation and the placenta of infants who were growth restricted and those that were small for gestational age (SGA).

METHOD OF STUDY

Placental villous tissue and maternal serum were obtained from pregnancies where infants were SGA at birth or who had a decreasing growth rate (≥25 centiles) across the third trimester. Immunohistochemical and histological analyses of placental samples were conducted for macrophage number, alongside vascular and cell turnover analysis. Inflammatory profile was analyzed in maternal and placental compartments via ELISAs and multiplex assays.

RESULTS

There were significantly more CD163⁺ macrophages in placentas of infants with a decreased growth rate compared to controls, but not in SGA infants (median 8.6/ nuclei vs 3.8 and 2.9, P = .008 and P = .003, respectively). Uric acid (P = .0007) and IL-8 (P = .0008) were increased in placentas, and S100A8 (P < .0002) was increased in maternal serum of infants with decreased growth rate. No changes in the maternal serum or placental lysates of SGA infants were observed.

CONCLUSION

The evidence of an altered inflammatory profile in infants with a decreasing growth rate, but not in those that were born SGA, provides further evidence that inflammation plays a role in true FGR. It remains unclear whether the increased placental macrophages occur as a direct result, or as a consequence of the pro-inflammatory environment observed in fetal growth restriction.

Verification of placental growth factor and soluble-fms-like tyrosine kinase 1 assay performance in late pregnancy and their diagnostic test accuracy in women with reduced fetal movement

BACKGROUND

Placental growth factor (PlGF) and soluble-fms-like tyrosine kinase 1 (sFlt-1) are biomarkers of placental function used to aid the diagnosis and prediction of pregnancy complications. This work verified the analytical performance of both biomarkers and provides preliminary diagnostic accuracy data to identify adverse pregnancy outcome in women with reduced fetal movement.

METHODS

Verification of sFlt-1 and PlGF assays included a comparative accuracy assessment of 24 serum samples analysed at six different sites and laboratory-specific precision estimates. The sFlt-1/PlGF ratio was assessed in serum samples obtained prospectively from 295 women with reduced fetal movement ≥36 weeks' gestation; diagnostic accuracy was evaluated using 2 × 2 tables and area under the receiver operator characteristic (AUROC) curve.

RESULTS

Regression analysis showed that performance between sites was good with Passing-Bablok slopes ranging from 0.96 to 1.05 (sFlt-1) and 0.93 to 1.08 (PlGF). All sites had a mean bias <15%, although there was poorer agreement at the lowest PlGF concentrations. All within- and between-batch coefficients of variation were <10%. In 289 women with an appropriately grown fetus, an sFlt-1/PlGF ratio ≥38 had a sensitivity of 0.20 (95% confidence interval [CI] 0.07, 0.41), specificity of 0.88 (95% CI 0.83, 0.92) and AUROC curve of 0.58 (95% CI 0.47, 0.68) to identify adverse pregnancy outcome.

CONCLUSIONS

Analytical performance of the sFlt-1 and PlGF assays was comparable across different sites. The sensitivity of sFlt-1/PlGF to identify adverse pregnancy outcome in women with reduced fetal movement was considered acceptable, in the absence of other tests, to progress to a pilot randomized controlled trial.

Standard care informed by the result of a placental growth factor blood test versus standard care alone in women with reduced fetal movement at or after 36+0 weeks' gestation: a pilot randomised controlled trial

Background

Biomarkers of placental function can potentially aid the diagnosis and prediction of pregnancy complications. This randomised controlled pilot trial assessed whether for women with reduced fetal movement (RFM), intervention directed by the measurement of a placental biomarker in addition to standard care was feasible and improved pregnancy outcome compared with standard care alone.

Methods

Women aged 16–50 years presenting at eight UK maternity units with RFM between 36⁺⁰ and 41⁺⁰ weeks’ gestation with a viable singleton pregnancy and no indication for immediate delivery were eligible. Participants were randomised 1:1 in an unblinded manner to standard care and a biomarker blood test result revealed and acted on (intervention arm) or standard care where the biomarker result was not available (control arm). The objectives were to determine the feasibility of a main trial by recruiting 175–225 participants over 9 months and to provide proof of concept that informing care by measurement of placental biomarkers may improve outcome. Feasibility was assessed via the number of potentially eligible women, number recruited, reasons for non-recruitment and compliance. Proof of concept outcomes included the rates of the induction of labour and caesarean birth, and a composite adverse pregnancy outcome.

Results

Overall, 2917 women presented with RFM ≥ 36 weeks, 352 were approached to participate and 216 (61%) were randomised (intervention n = 109, control n = 107). The main reason for not approaching women was resource/staff issues (n = 1510). Ninety-seven women declined the trial, mainly due to not liking blood tests (n = 24) or not wanting to be in a trial (n = 21). Compliance with the trial interventions was 100% in both arms. Labour was induced in 97 (45%) participants (intervention n = 49, control n = 48), while 17 (9%) had planned caesarean sections (intervention n = 9, control n = 8). Overall, 9 (8%) babies in the intervention arm had the composite adverse pregnancy outcome versus 4 (4%) in the control arm.

Conclusions

A main trial using a placental biomarker in combination with delivery, as indicated by the biomarker, in women with RFM is feasible. The frequency of adverse outcomes in this population is low, hence, a large sample size would be required along with consideration of the most appropriate outcome measures.

Trial registration

ISRCTN, ISRCTN12067514; registered 8 September 2017.

Intra-placental arterial Doppler: A marker of fetoplacental vascularity in late-onset placental disease?

INTRODUCTION

Late-gestation adverse pregnancy outcome is associated with reduced placental villous vascularity but rarely with a frankly abnormal umbilical artery Doppler waveform. The clinical utility of umbilical artery Doppler velocimetry in late gestation is limited by poor understanding of what aspect(s) of placental structure and function the impedance reflects. We hypothesized that placental arterial circulation impedance reflects placental vascularity and arterial function.

MATERIAL AND METHODS

This was a secondary analysis of data from the FEMINA2 study, a study of pregnancy outcome after reduced fetal movement. Forty-three pregnancies that delivered within 7 days of ultrasound assessment were examined. Impedance was quantified by pulsatility index (PI) from umbilical, chorionic plate arteries, and intra-placental arteries. Site-specific PI was compared with villous vascularity (CD31 immunostaining) and placental arterial function (wire myography) by regression analysis (P < .01) where factor analysis suggested potential co-variance (Eigen value > 2).

RESULTS

Pulsatility index decreased with proximity to the placental microvasculature (P < .0001). Intra-placental artery PI correlated significantly with vessel number (R²  = 0.40, P = .0007). No significant relations between umbilical or chorionic plate artery PI and villous vascularity were found (P ≥ .11 and P ≥ .042). No significant co-variance was suggested between PI at any Doppler sampling site and ex vivo placental arterial function indices. Measurement reliability (intraclass correlation coefficient) was highest in the umbilical artery (PI 0.75 and 0.50 for intra- and interoperator reliability, respectively) and lowest in the intra-placental arteries (PI 0.55 and 0.41, respectively). Systematic bias in umbilical artery PI was observed between observers, but not at other Doppler sampling sites.

CONCLUSIONS

More vascular placentas ex vivo are associated with reduced intra-placental artery Doppler impedance in utero. Although umbilical (but not intra-placental) artery Doppler PI is associated with adverse outcome after reduced fetal movement, this predictive ability does not appear to be through assessment of placental vascularity or chorionic plate arterial function. The inferior reliability of intra-placental artery Doppler, although similar to previously published reliability of umbilical artery Doppler, impairs its ability to detect subtle differences in placental vascularity, and must be significantly improved before it could be considered a clinically useful test.