The relationship between maternal placental growth factor levels and intrapartum fetal compromise

Angiogenic biomarkers for the follow-up of singleton pregnancies with suspected preeclampsia

BACKGROUND

Preeclampsia (PE) is a hypertensive disorder of pregnancy and one of the leading causes of maternal and fetal morbidity and mortality worldwide. While the underlying cause of remains unknown, abnormal placentation in early stages of pregnancy is thought to be a main triggering event for the more severe and early-onset forms. A consequence of placental insufficiency is an imbalance of angiogenic factors in the maternal circulation. The objective was to assess the utility of the angiogenic biomarker sFlt-1/PlGF for the diagnosis, follow-up and prognosis of preeclampsia.

METHODS

This was a retrospective cohort study based including 65 consecutive singleton pregnancies with suspected preeclampsia referred to our hospital between January 2018 and February 2019. PE was defined as early-onset (20-33+6 weeks) and late-onset (≥34 weeks). The main independent variable was sFlt-1/PlGF classified in women with early or late onset PE, respectively, as low when <38 or <38, intermediate when 38-84 or 38-109, and high when ≥85 or ≥110.

RESULTS

PE was confirmed in 14 (4 early-onset, 10 late-onset) of the participants. 122 sFlt-1/PIGF ratio determinations were requested. The optimal sFlt-1/PlGF to predict PE was ≥86 with a sensitivity of 93% and a specificity of 96% (AUC 0.95; CI 95% 0.90-1.0; P<0.001). A multilevel logistic model for the diagnosis of PE was adjusted for age, Body Mass Index, diabetes, proteinuria and mean arterial pressure. Women were 16.5 times (P=0.013) more likely to develop PE if they had intermediate sFlt-1/PlGF levels and 451 times (P<0.001) more likely if they had high biomarker levels compared to those with levels below 38. The probability of PE was 3.73 times (P=0.046) greater in those with maternal and/or fetal complications.

CONCLUSIONS

The biomarker proved useful to diagnose PE and assess its prognosis. Patients diagnosed with PE had a higher frequency of complications and their newborns were of lower birth weight.

Ulinastatin ameliorates preeclampsia induced by N(gamma)-nitro-l-arginine methyl ester in a rat model via inhibition of the systemic and placental inflammatory response

BACKGROUND

The pathogenesis of preeclampsia (PE) is associated with inflammation and endothelial damage. Ulinastatin (UTI) mainly inhibits proteolytic activity and significantly reduces the release of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) from macrophages. It also ameliorates vascular endothelial damage in pathological conditions. Hence, we investigated the effects of UTI in a rat model of PE induced using N(gamma)-nitro-l-arginine methyl ester (L-NAME).

METHODS

Although inducing PE in a rat model, 5000 U/kg of UTI were injected daily. Systolic blood pressure (SBP) and protein levels in the urine were measured. Renal function, and serum concentrations of TNF-α, IL-6, placental growth factor (PLGF), and von Willebrand factor (vWF) were evaluated. The number and weight of live fetuses as well as the weight of placentas were measured. Placentas were collected for western blot and pathological analysis.

RESULTS

UTI slightly ameliorated proteinuria and the increases in SBP, blood urea nitrogen (BUN), and serum creatinine. Furthermore, UTI improved serum and placental protein expression levels of TNF-α, IL-6, vWF, and PLGF. Pathological analysis revealed that vascular density and blood flow perfusion was enhanced, vessel wall thickening and neutrophil infiltration were diminished, and the weight and number of live fetuses as well as the weight of the placentas were improved with UTI.

CONCLUSION

Preventive use of UTI in the PE rat model induced by L-NAME partially alleviated hypertension, proteinuria, and impaired renal function; improved fetal growth restriction; diminished vascular endothelial injury; and ameliorated placental vasculogenesis abnormality and malperfusion by inhibiting the systemic and placental inflammatory response, suggesting that UTI is a potential drug for PE prevention or treatment.

Predelivery placenta-associated biomarkers and computerized intrapartum fetal heart rate patterns

Background

Increasing syncytiotrophoblast stress in term and postdate placentas is reflected by increasing antiangiogenic dysregulation in the maternal circulation, with low "proangiogenic" placental growth factor concentrations and increased "antiangiogenic" soluble fms-like tyrosine kinase-1 concentrations. Imbalances in these placenta-associated proteins are associated with intrapartum fetal compromise and adverse pregnancy and delivery outcome. Cardiotocography is widely used to assess fetal well-being during labor, but it is insufficient on its own for predicting adverse neonatal outcome. Development of improved surveillance tools to detect intrapartum fetal stress are needed to prevent neonatal adverse outcome.

Objective

This study aimed to assess whether predelivery circulating maternal angiogenic protein concentrations are associated with intrapartum computerized fetal heart rate patterns, as calculated by the Oxford System for computerized intrapartum monitoring (OxSys) 1.7 prototype. We hypothesized that in pregnancies with low "proangiogenic" placental growth factor levels, increased "antiangiogenic" soluble fms-like tyrosine kinase-1 levels, and increased soluble fms-like tyrosine kinase-1-placental growth factor ratio, the OxSys 1.7 prototype will generate more automated alerts, indicating fetal compromise. Our secondary objective was to investigate the relationship between maternal circulating placenta-associated biomarkers and rates of automated alerts in pregnancies with and without adverse neonatal outcome.

Study Design

This was an observational prospective cohort study conducted at a single tertiary center from September 2016 to March 2020. Of 1107 singleton pregnancies (gestational week ≥37⁺⁰), 956 had available prelabor and predelivery placental growth factor and soluble fms-like tyrosine kinase-1 concentrations and intrapartum cardiotocography recordings. All neonatal and delivery outcomes were externally reviewed and categorized into 2 groups-the "complicated" group (n=32) and the "uncomplicated" group (n=924)-according to predefined adverse neonatal outcome. Eight different cardiotocography features were calculated by OxSys 1.7: baseline at start of cardiotocography, baseline at end of cardiotocography, short-term variation at start, short-term variation at end, nonreactive initial trace, and throughout the entire cardiotocography, maximum decelerative capacity, total number of prolonged decelerations, and OxSys 1.7 alert. OxSys 1.7 triggered an alert if the initial trace was nonreactive or if decelerative capacity and/or the number of prolonged decelerations exceeded a predefined threshold. Included women and attending clinicians were blinded to both biomarker and OxSys 1.7 results.

Results

Mean maternal placental growth factor concentration was lower in the group with OxSys 1.7 alert compared with the group without the alert (151 vs 169 pg/mL; P=.04). There was a weak negative correlation between predelivery high soluble fms-like tyrosine kinase-1 and low short-term variation start (r _s=-0.068; 95% confidence interval, -0.131 to -0.004; P=.036), predelivery high soluble fms-like tyrosine kinase-1 and low short-term variation end (r _s=-0.068; 95% confidence interval, -0.131 to -0.005; P=.036), and high soluble fms-like tyrosine kinase-1-placental growth factor ratio and low short-term variation end (r _s=-0.071; 95% confidence interval, -0.134 to -0.008; P=.027). The rate of decelerative capacity alerts increased more rapidly as placental growth factor decreased in the "complicated" compared with the "uncomplicated" group (0% to 17% vs 4% to 8%).

Conclusion

More automated alerts indicative of fetal distress were generated by OxSys 1.7 in pregnancies with low maternal predelivery placental growth factor level, in line with likely increasing placental stress toward the end of the pregnancy. An antiangiogenic predelivery profile (lower placental growth factor) increased the rates of alerts more rapidly in pregnancies with adverse neonatal outcome compared with those without. We suggest that future studies developing and testing prediction tools for intrapartum fetal compromise include predelivery maternal placental growth factor measurements.

The association between placenta-associated circulating biomarkers and composite adverse delivery outcome of a likely placental cause in healthy post-date pregnancies

INTRODUCTION

Post-date pregnancies have an increased risk of adverse delivery outcome. Our aim was to explore the association between placenta-associated circulating biomarkers and composite adverse delivery outcome of a likely placental cause in clinically healthy post-date pregnancies.

MATERIAL AND METHODS

Women with healthy singleton post-date pregnancies between 40⁺² and 42⁺²  weeks of gestation were recruited to this prospective, observational study conducted at Oslo University Hospital, Norway (NCT03100084). Placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) were measured in the maternal serum samples closest to delivery. The composite adverse delivery outcome included fetal acidemia, low Apgar score (<4 at 1 min or <7 at 5 min), asphyxia, fetal death, assisted ventilation for more than 6 h, meconium aspiration, hypoxic-ischemic encephalopathy, therapeutic hypothermia, operative delivery due to fetal distress, or pathological placental histology findings. Two study-independent senior consultant obstetricians blinded to biomarker results concluded, based on clinical expert opinion, whether the adverse delivery outcomes were most likely associated with placental dysfunction ("likely placental cause") or not. Means were compared using one-way analysis of variance and Bonferroni corrected pairwise comparisons between groups. Receiver operating characteristic (ROC) curves assessed the predictive ability of PlGF, sFlt-1/PlGF ratio, and PlGF <10th centile after adjustment for gestational age at blood sampling.

RESULTS

Of 501 pregnancies reviewed for predefined adverse delivery outcomes and for a likely placental cause, 468 were healthy pregnancies and subsequently assigned to either the "uncomplicated" (no adverse outcome, n = 359), "intermediate" (non-placental cause/undetermined, n = 90), or "complicated" (likely placental cause, n = 19) group. There was a significant difference in mean PlGF and sFlt-1/PlGF ratio between the "complicated", "intermediate", and "uncomplicated" groups (108, 185, and 179 pg/mL, p = 0.001; and 48.3, 23.4, and 24.6, p = 0.002, respectively). There was a higher proportion of PlGF concentration <10th centile in the "complicated" group compared with the "intermediate" and "uncomplicated" groups (42.1% vs. 11.1% and 9.5%, p = 0.001). The largest area under the ROC curve for predicting "complicated" outcome was achieved by PlGF concentration and gestational age at blood sampling (0.76; 95% CI 0.65-0.86).

CONCLUSIONS

In clinically healthy post-date pregnancies, an antiangiogenic pre-delivery profile (lower PlGF level and higher sFlt-1/PlGF ratio) was associated with composite adverse delivery outcome of a likely placental cause.

Maternal placental growth factor and soluble fms-like tyrosine kinase-1 reference ranges in post-term pregnancies: A prospective observational study

Background

Post-term pregnancies have increased risks for adverse fetal and maternal outcomes. Maternal concentrations of the placenta-associated proteins placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) have been identified as predictors for preeclampsia and fetal growth restriction, both syndromes of placental dysfunction. We have proposed that low maternal circulating PlGF and increased sFlt-1 are general markers for syncytiotrophoblast stress, which increases at and beyond term, even in apparently uncomplicated pregnancies. Our aim was to establish circulating PlGF, sFlt-1, and sFlt-1/PlGF reference ranges in healthy post-term pregnancies (gestational week ≥40⁺²), comparing with healthy term pregnancies and evaluating associations between time to delivery and biomarker percentiles.

Methods

Of 501 healthy, singleton post-term pregnancies prospectively recruited between September 2016 and December 2017 at our tertiary obstetric department, 426 with an uncomplicated delivery outcome contributed PlGF and sFlt-1 serum concentrations for reference range construction. A retrospective, cross-sectional, term group with an uncomplicated delivery outcome (n = 146) served as comparison. Differences in percentile values between groups and confidence intervals were calculated by quantile regression.

Results

In post-term pregnancies the 5^th, 50^th, and 95^th percentiles for PlGF were: 70, 172, and 496 pg/mL; for sFlt-1: 2074, 4268, and 9141 pg/mL; and for sFlt-1/PlGF 5.3, 25.5, and 85.2. Quantile regression analyses comparing the post-term to the term group showed for PlGF a trend towards higher 10^th through 30^th percentiles, for sFlt-1 significantly higher 10^th through 80^th percentiles, and for sFlt-1/PlGF ratio significantly higher 30^th percentile and significantly lower 95^th percentile.

PlGF below the 5^th percentile and sFlt-1/PlGF ratio above the 95^th percentile was associated with shorter time to delivery (p = 0.031 and p = 0.025, respectively).

Conclusions

Our findings support the concept of increasing syncytiotrophoblast stress post-term in clinically healthy pregnancies. Whether post-term dysregulated angiogenic markers reflect a biological placental clock merits further investigation.

Melatonin Levels Decrease in the Umbilical Cord in Case of Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) is a common reason for perinatal morbidity and mortality. Also, it is often complicated with fetal distress. Melatonin is widely known as an anti-oxidant agent, and it might decrease the damage of tissues caused by hypoxia. It is also known that levels of pro- and anti-inflammatory cytokines are changed during pregnancy. Placental growth factor (PlGF) is responsible for the angiogenesis in the placenta. We aimed to investigate whether the level of melatonin, cytokines, and PlGF in umbilical blood after birth is different in the case of IUGR compared to normal fetuses. Fourteen women whose pregnancies were complicated with IUGR were included in the study group. The presence of IUGR was confirmed by ultrasound fetometry in the third pregnancy trimester, 30-36 weeks of gestation. All patients delivered their children vaginally after 37 weeks of pregnancy. The cases of severe fetal distress that required a caesarian section, obstetrical forceps, or vacuum extraction of the fetus were excluded from the study. We found that the concentrations of cytokines did not differ significantly between the groups. Also, no significant difference in the daytime of delivery was found between the groups. The concentrations of melatonin and PlGF in the umbilical blood at labor were significantly lowered in the case of IUGR compared to normal pregnancies. This fact, as we consider, is caused by altered production of melatonin and PlGF by the placenta. Therefore, the protective action of these two factors for the fetus at labor is decreased in IUGR.

Prelabor screening at term using the cerebroplacental ratio and placental growth factor: a pragmatic randomized open-label phase 2 trial

BACKGROUND AND OBJECTIVE

In some women placental function may not be adequate to meet fetal growth requirements in late pregnancy or the additional demands during labor, thus predisposing these infants to intrapartum fetal compromise and subsequent serious morbidity and mortality. The objective of this study was to determine if the introduction of a prelabor screening test at term combining the cerebroplacental ratio and maternal placental growth factor level would result in a reduction in a composite of adverse outcomes.

STUDY DESIGN

Single-site, nonblinded, randomized controlled trial conducted at a tertiary hospital in Brisbane, Australia. Eligible women were randomized to either receive the screening test performed between 37-38 weeks or routine obstetric care. Screen-positive women were offered induction of labor. The primary outcome was a composite of emergency cesarean delivery for nonreassuring fetal status (fetal distress) or severe neonatal acidosis or low Apgar score or stillbirth or neonatal death.

RESULTS

Women were recruited and randomized (n = 501) between April 2017 and January 2019. Sixty-three of 249 subjects (25.3%) in the screened group compared to 56 of 252 (22.2%) in the control group experienced the primary outcome (relative risk = 1.14 [95% confidence interval, 0.83-1.56]; P = .418). Women who screened positive were more likely to require operative delivery for fetal distress, have meconium-stained liquor, have pathologic fetal heart rate abnormalities, and have infants with lower birthweight compared to women that screened negative.

CONCLUSION

The introduction of this test did not result in improvements in intrapartum intervention rates or neonatal outcomes. However, it did show discriminatory potential, and future research should focus on refining the thresholds used.

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.

The physiology of intrapartum fetal compromise at term

Uterine contractions in labor result in a 60% reduction in uteroplacental perfusion, causing transient fetal and placental hypoxia. A healthy term fetus with a normally developed placenta is able to accommodate this transient hypoxia by activation of the peripheral chemoreflex, resulting in a reduction in oxygen consumption and a centralization of oxygenated blood to critical organs, namely the heart, brain, and adrenals. Providing there is adequate time for placental and fetal reperfusion between contractions, these fetuses will be able to withstand prolonged periods of intermittent hypoxia and avoid severe hypoxic injury. However, there exists a cohort of fetuses in whom abnormal placental development in the first half of pregnancy results in failure of endovascular invasion of the spiral arteries by the cytotrophoblastic cells and inadequate placental angiogenesis. This produces a high-resistance, low-flow circulation predisposing to hypoperfusion, hypoxia, reperfusion injury, and oxidative stress within the placenta. Furthermore, this renders the placenta susceptible to fluctuations and reduction in uteroplacental perfusion in response to external compression and stimuli (as occurs in labor), further reducing fetal capillary perfusion, placing the fetus at risk of inadequate gas/nutrient exchange. This placental dysfunction predisposes the fetus to intrapartum fetal compromise. In the absence of a rare catastrophic event, intrapartum fetal compromise occurs as a gradual process when there is an inability of the fetal heart to respond to the peripheral chemoreflex to maintain cardiac output. This may arise as a consequence of placental dysfunction reducing pre-labor myocardial glycogen stores necessary for anaerobic metabolism or due to an inadequate placental perfusion between contractions to restore fetal oxygen and nutrient exchange. If the hypoxic insult is severe enough and long enough, profound multiorgan injury and even death may occur. This review provides a detailed synopsis of the events that can result in placental dysfunction, how this may predispose to intrapartum fetal hypoxia, and what protective mechanisms are in place to avoid hypoxic injury.

Role of sFlt-1/PlGF ratio and feto-maternal Doppler for the prediction of adverse perinatal outcome in late-onset pre-eclampsia

PURPOSE

The sFlt-1 (soluble fms-like tyrosine kinase-1)/PlGF (placental growth factor) ratio and uterine artery Doppler have shown to be helpful in the diagnosis of pre-eclampsia (PE). The predictive value of the cerebroplacental ratio (CPR) regarding adverse perinatal outcome (APO) in low-risk pregnancies is intensively discussed. We evaluated the extent to which sFlt-1/PlGF ratio and feto-maternal Doppler may be useful in predicting APO in singleton pregnancies complicated by late-onset PE and/or HELLP syndrome.

METHODS

This is a retrospective study from 2010 to 2018 consisting of singleton pregnancies with confirmed diagnosis of late-onset (lo ≥ 34 weeks) PE/HELLP syndrome in which sFlt-1/PlGF ratio and feto-maternal Doppler (mUtA-PI: mean uterine artery pulsatility index and CPR) were determined. The ability of sFlt-1/PlGF ratio, mUtA-PI, CPR and their combination to predict APO or SGA was evaluated using receiver operating characteristic (ROC) curves.

RESULTS

67 patients were included in the final analysis. Of these, sFlt-1/PlGF was > 110 (defining angiogenic lo PE) in 40.3% (27/67), mUtA-PI was above the 95th centile in 34.3% (23/67) patients and CPR was lower than the 5th centile in 10.4% (7/67). Abnormal sFlt-1/PlGF and mUtA-PI as well as CPR were associated with a lower birth weight (BW). Late-preterm birth (< 37 weeks) as well as postnatal diagnosis of small for gestational age (SGA: BW < 3rd centile) was significantly more often in angiogenic lo PE cases. Neither sFlt-1/PIGF nor CPR or mUtA-PI were APO predictors. Only for sFlt-1/PlGF, ROC analysis revealed a significant predictive value for postnatal SGA (AUC = 0.856, p = 0.001, 95% CI 0.75-0.97). There was no statistical added value of combined SGA predictors as compared to sFlt-1/PlGF alone.

CONCLUSIONS

In patients with lo PE, adding sFlt-1/PlGF ratio to routine antepartum fetal surveillance may be useful to identify cases of postnatal SGA. However, further prospective studies are warranted to define the role of feto-maternal Doppler and sFlt-1/PlGF ratio as outcome predictors.

Reference centiles for maternal placental growth factor levels at term from a low-risk population

INTRODUCTION

Placental growth factor (PLGF) is a biomarker of placental function. The aim of this study was to define reference ranges for maternal PLGF levels in a normotensive cohort ≥36 + 0 weeks.

METHOD

Prospective observational data from Mater Mothers' Hospital, Brisbane. PLGF levels were measured in women at ≥36 + 0 weeks with singleton, non-anomalous pregnancies. Women with hypertension and fetal growth restriction were excluded. PLGF (pg/mL) was assayed using DELFIA® Xpress (PerkinElmer Inc). The Generalised Additive Model for Location, Shape and Scale (GAMLSS) method was used for the calculation of gestational age-adjusted centiles. Data analysis was performed with Stata 13 (StataCorp, LLC) and R software (R Foundation for Statistical Computing, Vienna, Austria). In all women, PLGF was measured within 2 weeks of delivery.

RESULTS

The study cohort comprised of 845 women (36 weeks n = 73, 37 weeks n = 230, 38 weeks n = 214, 39 weeks n = 172, 40 weeks n = 115, 41weeks n = 41). PLGF levels were negatively correlated with gestational age (r = -0.20, p < 0.001). Median PLGF levels dropped significantly from 36 weeks to 41 weeks (169.0 pg/mL to 96.6 pg/mL, p < 0.001). Gestational age specific maternal PLGF centiles were reported using fractional polynomial additive term and Box-Cox t distribution. PLGF did not perform adequately as a predictive test for adverse perinatal outcomes (AUC <0.6).

DISCUSSION

We have created gestational centile reference ranges for maternal PLGF from a normotensive cohort. These novel data suggest maternal PLGF levels decline ≥36 + 0 weeks. The utility of PLGF as a predictor of adverse perinatal outcomes at term, should be further investigated with clinical trials.

Reduced growth velocity at term is associated with adverse neonatal outcomes in non-small for gestational age infants

OBJECTIVES

To investigate the association between decreased growth velocity at term, measured by estimated fetal weight z-score change, and adverse neonatal outcome and operative birth for intrapartum fetal compromise in a cohort of non-small for gestational age infants.

STUDY DESIGN

A prospective observational study was conducted at Mater Mothers' Hospital, Brisbane, Australia. Serial ultrasound assessment was undertaken every two weeks from 36 weeks gestation until delivery to determine estimated fetal weight on 436 women with uncomplicated pregnancies. Intrapartum and neonatal outcomes were recorded. The outcome measures were adverse neonatal outcome [severe acidosis (cord pH < 7.0, base deficit ≤-12 mmol/L and/or lactate >6 mmol/L), low Apgar score (<7 at 5 min) or neonatal intensive care unit admission] and operative delivery for intrapartum fetal compromise. Estimated fetal weight z-score change was compared between those with and without adverse neonatal outcome and operative delivery for intrapartum fetal compromise using Generalised Linear Mixed Models.

RESULTS

The estimated fetal weight z-score per week declined for infants with the adverse neonatal outcome whilst those without demonstrated an increase [-0.04 (0.18) vs. 0.02 (0.21), p = 0.02]. There was no difference in estimated fetal weight z-score change per week in those with and without operative delivery for intrapartum fetal compromise.

CONCLUSION

Reduced growth velocity in non-small for gestational age fetuses at term is associated with an increased risk of adverse neonatal outcomes.

Changes in intrapartum maternal placental growth factor levels in pregnancies complicated by fetal compromise at term

BACKGROUND

Intrapartum fetal compromise (IFC) may result from the gradual decline in placental function during labour and can precipitate adverse neonatal outcomes. Placental growth factor (PlGF) is a biomarker of placental function. This study aims to investigate maternal PlGF levels and adverse perinatal outcomes in term labour.

METHODS

Prospective observational study (Mater Mothers' Hospital, Brisbane). Eligibility: 37⁺⁰- 42⁺⁰ weeks gestation, singleton, cephalic, non-anomalous pregnancies. Cases of pre-eclampsia and fetal growth restriction were excluded. Maternal PlGF was sampled at the onset of the first stage of labour (1st PlGF) and again at the second stage (2nd PlGF).

RESULTS

Sixty-three participants met inclusion criteria. Women requiring operative delivery (n = 11) for IFC had lower 1st PlGF (90.8 vs. 111.8 pg/ml) and 2nd PlGF (65.8 vs. 83.7 pg/ml) compared to the no-IFC cohort (n = 52). PlGF levels decreased significantly during labour in both the IFC (90.8 vs. 65.8 pg/ml, p = 0.021) and no-IFC (111.8 v 83.7, p < 0.001) cohorts, although the decline in PlGF levels was greater in the IFC cohort (-41.8% vs. -23.4%, p = 0.385). Maternal PlGF levels were significantly lower in those with an abnormal fetal heart rate pattern, cord arterial pH < 7.2, nursery admission and composite adverse neonatal outcome (CANO). PlGF decline was not correlated to duration of labour but was influenced by nulliparity and induced labour.

CONCLUSIONS

Maternal PlGF levels are lower in pregnancies complicated by IFC and CANO, and declines more sharply during labour compared to the no-IFC cohort. The utility of PlGF as a predictor of IFC should be further investigated with clinical trials.

Prelabor screening for intrapartum fetal compromise in low-risk pregnancies at term: cerebroplacental ratio and placental growth factor

OBJECTIVES

To determine the screening performance of low fetal cerebroplacental ratio (CPR), a marker of fetal adaptation to suboptimal growth, and maternal placental growth factor (PlGF) level, both in isolation and in combination, for the prediction of Cesarean section (CS) for intrapartum fetal compromise (IFC) and composite adverse neonatal outcome (CANO).

METHODS

This was a prospective cohort study in low-risk women with uncomplicated singleton pregnancy from 36 weeks' gestation to delivery. CPR and PlGF were assessed fortnightly and intrapartum and neonatal outcomes were recorded. CPR and PlGF values from the final assessment for each woman were corrected for gestational age and assessed for screening performance, firstly as continuous variables and then as binary predictors.

RESULTS

Of the 264 women who consented to participate in the study, 207 were included in the final analysis. Seven pregnancies required CS for IFC and 38 had CANO. Pregnancies delivered by CS for IFC had lower CPR and PlGF centiles than those in all other pregnancies. Pregnancies with CANO had a lower PlGF centile. The greatest areas under the receiver-operating characteristics curves (AUCs) for the prediction of CS for IFC (0.92; 95% CI, 0.86-0.97) and CANO (0.64; 95% CI, 0.54-0.74) were achieved by a combination of CPR 20^th and PlGF 33^rd centile thresholds. This produced sensitivities, specificities and positive likelihood ratios for the prediction of CS for IFC of 100%, 86% and 7.14, respectively, and 34.2%, 87.0% and 2.63, respectively, for the prediction of CANO. There was no statistical difference in the AUC for CS for IFC between the combined model and when CPR was used alone, or for CANO between the combined model and CPR or PlGF in isolation.

CONCLUSIONS

This pilot proof-of-concept study describes the screening performance of CPR and maternal PlGF level for CS for IFC in low-risk women from 36 weeks' gestation. It was found that CPR and maternal PlGF improved the overall predictive utility for CS for IFC, as well as that for CANO. However, given the lack of significant difference between the combined model and its individual components, it is debatable whether the combined model is a superior screening test. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Birth-weight centiles and the risk of serious adverse neonatal outcomes at term

BACKGROUND

Birth-weight is an important determinant of perinatal outcome with low birth-weight being a particular risk factor for adverse consequences.

AIM

To investigate the impact of neonatal sex, mode of birth and gestational age at birth according to birth-weight centile on serious adverse neonatal outcomes in singleton term pregnancies.

MATERIALS AND METHODS

This was a retrospective cohort study of singleton term births at the Mater Mother's Hospital, Brisbane, Australia. Serious adverse neonatal outcome was defined as a composite of severe acidosis at birth (pH ≤7.0 and/or lactate ≥6 mmol/L and/or base excess ≤-12 mmol/L), Apgar <3 at 5 min, neonatal intensive-care unit admission and antepartum or neonatal death. The main exposure variable was birth-weight centile.

RESULTS

Of the 69,210 babies in our study, the overall proportion of serious adverse neonatal outcomes was 9.1% (6327/69,210). Overall, neonates in the <3rd birth-weight centile category had the highest adjusted odds ratio (OR) for serious adverse neonatal outcomes [OR 3.53, 95% confidence interval (CI) 3.06-4.07], whilst those in the ≥97th centile group also had elevated odds (OR 1.51, 95% CI 1.30-1.75). Regardless of birth modality, smaller babies in the <3rd centile group had the highest adjusted OR and predicted probability for serious adverse neonatal outcomes. When stratified by sex, male babies consistently demonstrated a higher predicted probability of serious adverse neonatal outcomes across all birth-weight centiles. The adjusted odds, when stratified by gestational age at birth, were the highest from 37+0 to 38+6 weeks in the <3rd centile group (OR 5.97, 95% CI 4.60-7.75).

CONCLUSIONS

Low and high birth-weights are risk factors for serious adverse neonatal outcomes. The adjusted OR appears to be greatest for babies in the <3rd birth-weight centile group, although an elevated risk was also found in babies within the ≥97th centile category.

Maternal demographic factors associated with emergency caesarean section for non-reassuring foetal status

OBJECTIVES

This study aimed to determine maternal and obstetric factors associated with emergency caesarean section (CS) for non-reassuring foetal status (NRFS).

MATERIALS AND METHODS

This was a retrospective analysis of term singleton births between January 2007 and December 2015 at the Mater Mother's Hospital in Brisbane. The study group comprised all cases of emergency CS for NRFS, and the control cohort comprised all other births meeting the inclusion criteria but excluding those in the study cohort.

RESULTS

Over the study period, there were 74,177 births fulfilling the inclusion criteria. The overall rate of emergency CS for NRFS was 4.2% (3132/74,177). Multivariate analysis showed that being overweight and obese, Indian and "other" ethnicity, artificial reproductive techniques, smoking, induction of labour and gestation at 39-42 weeks were associated with an increased risk, whereas being underweight, female sex, hypertension and birth without labour conferred a lower risk.

CONCLUSION

Many maternal and obstetric factors were associated with emergency CS for NRFS and influenced adverse perinatal outcomes. Recognition of these risk factors could help risk stratify women prior to labour.

Predicting intrapartum fetal compromise at term using the cerebroplacental ratio and placental growth factor levels (PROMISE) study: randomised controlled trial protocol

INTRODUCTION

Intrapartum complications are a major contributor to adverse perinatal outcomes, including stillbirth, hypoxic-ischaemic brain injury and subsequent longer term disability. In many cases, hypoxia develops as a gradual process due to the inability of the fetus to tolerate the stress of parturition suggesting reduced fetoplacental reserve before labour commences. The fetal cerebroplacental ratio (CPR) is an independent predictor of intrapartum fetal compromise, poor acid base status at birth and of neonatal unit admission at term. Similarly, circulating maternal levels of placental growth factor (PlGF) are lower in pregnancies complicated by placental dysfunction. This paper outlines the protocol for the PROMISE Study, which aims to determine if the introduction of a prelabour screening test for intrapartum fetal compromise combining the CPR and maternal PlGF level results in a reduction of adverse perinatal outcomes.

METHODS AND ANALYSIS

This is a single-site, non-blinded, individual patient randomised controlled trial of a screening test performed at term, combining the fetal CPR and maternal serum PlGF. Women with a singleton, non-anomalous pregnancy will be recruited after 34 weeks' gestation and randomised to either receive the screening test or not. Screened pregnancies determined to be at risk will be recommended induction of labour. Demographic, obstetric history and antenatal data will be collected at enrolment, and perinatal outcomes will be recorded after delivery. Relative risks and 95% CIs will be reported for the primary outcome. Regression techniques will be used to examine the influence of prognostic factors on the primary and secondary outcomes.

ETHICS AND DISSEMINATION

This study has been reviewed and approved by the Mater Human Research Ethics Committee (Reference: HREC EC00332) and will follow the principles of Good Clinical Practice. The study results will be disseminated at national and international conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ACTRN12616001009404; Pre-results.

Systematic review of maternal Placental Growth Factor levels in late pregnancy as a predictor of adverse intrapartum and perinatal outcomes

AIM

This systematic review evaluates the utility of maternal Placental Growth Factor (PlGF) when measured in late pregnancy (>20 weeks) as a predictor of adverse obstetric and perinatal outcomes.

METHODS

Pubmed and Embase were searched using the term "placental growth factor" in combination with relevant perinatal outcomes. Studies were included if they measured PlGF levels in pregnant women after 20 + 0 weeks gestation and reported relevant adverse obstetric or perinatal outcomes related to placental insufficiency (excluding pre-eclampsia).

RESULTS

Twenty-six studies were eligible for inclusion with 21 studies investigating the relationship between PlGF and small for gestational age (SGA) and 7 studies investigating PlGF for the prediction of other adverse perinatal outcomes. In all studies, maternal PlGF levels were significantly lower in the SGA group compared to controls. Other outcomes investigated included caesarean section (CS) for fetal compromise, low Apgar score, neonatal intensive care unit (NICU) admission, neonatal acidosis, stillbirth, and intrapartum fetal compromise. The results generally showed a significant association between low PlGF levels and CS for fetal compromise, NICU admission and stillbirth.

CONCLUSION

Low maternal PlGF levels in late pregnancy are strongly associated with SGA. Findings across studies were variable in relation to PlGF and the prediction of other adverse intrapartum and perinatal outcomes, however there was a consistent association between low PlGF levels and CS for fetal compromise, NICU admission and stillbirth. This review suggests that the use of PlGF for the prediction of adverse outcomes is promising. Its predictive value may potentially be enhanced if used in combination with other biomarkers or biophysical measures of fetal well-being.

Review: Systematic review of the utility of the fetal cerebroplacental ratio measured at term for the prediction of adverse perinatal outcome

AIM

This systematic review evaluates the utility of the fetal cerebroplacental ratio (CPR) when assessed at term (from 37 + 0 weeks gestation) as a predictor of adverse obstetric and perinatal outcomes.

DATA SOURCES AND SEARCH STRATEGY

An electronic search of Pubmed and Embase using variations of 'cerebroplacental ratio' and 'cerebroumbilical ratio' was conducted by two independent reviewers. Full text studies written in English that reported on low CPR and its correlation with relevant obstetric and perinatal outcomes were included.

RESULTS

Twenty one studies satisfied inclusion with 13 prospective and eight retrospective analyses. Fetal CPR was predictive of caesarean section for intrapartum fetal compromise, small for gestational age and fetal growth restriction and neonatal intensive care unit admission. Low CPR was also significantly associated with abnormal fetal heart rate pattern, meconium stained liquor, low Apgar score, acidosis at birth and composite adverse perinatal outcome scores. The CPR when taken at term had comparable if not better predictive value than that when taken at preterm. Most studies included small for gestational age fetuses and postdate pregnancies. Subtle variation existed in the threshold for low CPR.

CONCLUSION

The CPR at term has a strong association with adverse obstetric and perinatal outcomes. This review suggests the predictive utility of CPR at term is promising however there is insufficient evidence to demonstrate its value as a stand-alone test. Inclusion of CPR as a component of clinical care may help better identify fetuses at risk of adverse outcome, and this should be tested with randomised control trials.