Angiogenic and vasoactive proteins in the maternal-fetal interface in healthy pregnancies and preeclampsia.

BACKGROUND: Preeclampsia is characterized by maternal endothelial activation and placental dysfunction. Imbalance in maternal angiogenic and vasoactive factors has been linked to the pathophysiology. The contribution of the placenta as a source of these factors remains unclear. Furthermore, little is known about fetal angiogenic and vasoactive proteins and the relation between maternal and fetal levels. OBJECTIVE: We describe placental growth factor, soluble Fms-like tyrosine kinase 1, soluble endoglin, and endothelin 1-3 in 5 vessels in healthy pregnancies, early- and late-onset preeclampsia. Specifically, we aimed to (1) compare protein abundance in vessels at the maternal-fetal interface between early- and late-onset preeclampsia, and healthy pregnancies, (2) describe placental uptake and release of proteins, and (3) describe protein abundance in the maternal vs fetal circulations. STUDY DESIGN: Samples were collected from the maternal radial artery, uterine vein and antecubital vein, and fetal umbilical vein and artery in 75 healthy and 37 preeclamptic mother-fetus pairs (including 19 early-onset preeclampsia and 18 late-onset preeclampsia), during scheduled cesarean delivery. This method allows estimation of placental release and uptake of proteins by calculation of venoarterial differences on each side of the placenta. The microarray-based SomaScan assay quantified the proteins. RESULTS: The abundance of soluble Fms-like tyrosine kinase 1 and endothelin 1 was higher in the maternal vessels in preeclampsia than in healthy pregnancies, with the highest abundance in early-onset preeclampsia. Placental growth factor was lower in the maternal vessels in early-onset preeclampsia than in both healthy and late-onset preeclampsia. Maternal endothelin 2 was higher in preeclampsia, with late-onset preeclampsia having the highest abundance. Our model confirmed placental release of placental growth factor and soluble Fms-like tyrosine kinase 1 to the maternal circulation in all groups. The placenta released soluble Fms-like tyrosine kinase 1 into the fetal circulation in healthy and late-onset preeclampsia pregnancies. Fetal endothelin 1 and soluble Fms-like tyrosine kinase 1 were higher in early-onset preeclampsia, whereas soluble endoglin and endothelin 3 were lower in both preeclampsia groups than healthy controls. Across groups, abundances of placental growth factor, soluble Fms-like tyrosine kinase 1, and endothelin 3 were higher in the maternal artery than the fetal umbilical vein, whereas endothelin 2 was lower. CONCLUSION: An increasing abundance of maternal soluble Fms-like tyrosine kinase 1 and endothelin 1 across the groups healthy, late-onset preeclampsia and early-onset combined with a positive correlation may suggest that these proteins are associated with the pathophysiology and severity of the disease. Elevated endothelin 1 in the fetal circulation in early-onset preeclampsia represents a novel finding. The long-term effects of altered protein abundance in preeclampsia on fetal development and health remain unknown. Further investigation of these proteins' involvement in the pathophysiology and as treatment targets is warranted.

Maternal vascular indices at 36 weeks' gestation in the prediction of preeclampsia.

BACKGROUND: Epidemiological studies have shown that women with preeclampsia (PE) are at increased long term cardiovascular risk. This risk might be associated with accelerated vascular ageing process but data on vascular abnormalities in women with PE are scarce. OBJECTIVE: This study aimed to identify the most discriminatory maternal vascular index in the prediction of PE at 35 to 37 weeks' gestation and to examine the performance of screening for PE by combinations of maternal risk factors and biophysical and biochemical markers at 35 to 37 weeks' gestation. STUDY DESIGN: This was a prospective observational nonintervention study in women attending a routine hospital visit at 35 0/7 to 36 6/7 weeks' gestation. The visit included recording of maternal demographic characteristics and medical history, vascular indices, and hemodynamic parameters obtained by a noninvasive operator-independent device (pulse wave velocity, augmentation index, cardiac output, stroke volume, central systolic and diastolic blood pressures, total peripheral resistance, and fetal heart rate), mean arterial pressure, uterine artery pulsatility index, and serum concentration of placental growth factor and soluble fms-like tyrosine kinase-1. The performance of screening for delivery with PE at any time and at <3 weeks from assessment using a combination of maternal risk factors and various combinations of biomarkers was determined. RESULTS: The study population consisted of 6746 women with singleton pregnancies, including 176 women (2.6%) who subsequently developed PE. There were 3 main findings. First, in women who developed PE, compared with those who did not, there were higher central systolic and diastolic blood pressures, pulse wave velocity, peripheral vascular resistance, and augmentation index. Second, the most discriminatory indices were systolic and diastolic blood pressures and pulse wave velocity, with poor prediction from the other indices. However, the performance of screening by a combination of maternal risk factors plus mean arterial pressure was at least as high as that of a combination of maternal risk factors plus central systolic and diastolic blood pressures; consequently, in screening for PE, pulse wave velocity, mean arterial pressure, uterine artery pulsatility index, placental growth factor, and soluble fms-like tyrosine kinase-1 were used. Third, in screening for both PE within 3 weeks and PE at any time from assessment, the detection rate at a false-positive rate of 10% of a biophysical test consisting of maternal risk factors plus mean arterial pressure, uterine artery pulsatility index, and pulse wave velocity (PE within 3 weeks: 85.2%; 95% confidence interval, 75.6%-92.1%; PE at any time: 69.9%; 95% confidence interval, 62.5%-76.6%) was not significantly different from a biochemical test using the competing risks model to combine maternal risk factors with placental growth factor and soluble fms-like tyrosine kinase-1 (PE within 3 weeks: 80.2%; 95% confidence interval, 69.9%-88.3%; PE at any time: 64.2%; 95% confidence interval, 56.6%-71.3%), and they were both superior to screening by low placental growth factor concentration (PE within 3 weeks: 53.1%; 95% confidence interval, 41.7%-64.3%; PE at any time: 44.3; 95% confidence interval, 36.8%-52.0%) or high soluble fms-like tyrosine kinase-1-to-placental growth factor concentration ratio (PE within 3 weeks: 65.4%; 95% confidence interval, 54.0%-75.7%; PE at any time: 53.4%; 95% confidence interval, 45.8%-60.9%). CONCLUSION: First, increased maternal arterial stiffness preceded the clinical onset of PE. Second, maternal pulse wave velocity at 35 to 37 weeks' gestation in combination with mean arterial pressure and uterine artery pulsatility index provided effective prediction of subsequent development of preeclampsia.

Preeclampsia at term: evidence of disease heterogeneity based on the profile of circulating cytokines and angiogenic factors.

BACKGROUND: Intravascular inflammation and an antiangiogenic state have been implicated in the pathophysiology of preeclampsia. On the basis of the profiles of their angiogenic/antiangiogenic factors, women with preeclampsia at term may be classified into 2 subgroups with different characteristics and prevalence of adverse outcomes. This study was undertaken to examine whether these 2 subgroups of preeclampsia at term also show differences in their profiles of intravascular inflammation. OBJECTIVE: This study aimed to determine the plasma profiles of cytokines and chemokines in women with preeclampsia at term who had a normal or an abnormal angiogenic profile. STUDY DESIGN: A nested case-control study was conducted to include women classified into 3 groups: women with an uncomplicated pregnancy (n=213) and women with preeclampsia at term with a normal (n=55) or an abnormal (n=41) angiogenic profile. An abnormal angiogenic profile was defined as a plasma ratio of placental growth factor and soluble fms-like tyrosine kinase-1 multiple of the median <10th percentile for gestational age. Concentrations of cytokines were measured by multiplex immunoassays. RESULTS: Women with preeclampsia at term and an abnormal angiogenic profile showed evidence of the greatest intravascular inflammation among the study groups. These women had higher plasma concentrations of 5 cytokines (interleukin-6, interleukin-8, interleukin-12/interleukin-23p40, interleukin-15, and interleukin-16) and 7 chemokines (eotaxin, eotaxin-3, interferon-γ inducible protein-10, monocyte chemotactic protein-4, macrophage inflammatory protein-1ß, macrophage-derived chemokine, and thymus and activation-regulated chemokine compared to women with an uncomplicated pregnancy. By contrast, women with preeclampsia at term and a normal angiogenic profile, compared to women with an uncomplicated pregnancy, had only a higher plasma concentration of monocyte chemotactic protein-4. A correlation between severity of the antiangiogenic state, blood pressure, and plasma concentrations of a subset of cytokines was observed. CONCLUSION: Term preeclampsia can be classified into 2 clusters. One is characterized by an antiangiogenic state coupled with an excessive inflammatory process, whereas the other has neither of these features. These findings further support the heterogeneity of preeclampsia at term and may explain the distinct clinical outcomes.

Prediction of preterm birth in growth-restricted and appropriate-for-gestational-age infants using maternal PlGF and the sFlt-1/PlGF ratio-A prospective study.

OBJECTIVE: To assess the utility of placental growth factor (PlGF) levels and the soluble fms-like tyrosine kinase-1/placental growth factor (sFlt-1/PlGF) ratio to predict preterm birth (PTB) for infants with fetal growth restriction (FGR) and those appropriate for gestational age (AGA). DESIGN: Prospective, observational cohort study. SETTING: Tertiary maternity hospital in Australia. POPULATION: There were 320 singleton pregnancies: 141 (44.1%) AGA, 83 (25.9%) early FGR (<32+0 weeks) and 109 (30.0%) late FGR (≥32+0 weeks). METHODS: Maternal serum PlGF and sFlt-1/PlGF ratio were measured at 4-weekly intervals from recruitment to delivery. Low maternal PlGF levels and elevated sFlt-1/PlGF ratio were defined as <100 ng/L and >5.78 if <28 weeks and >38 if ≥28 weeks respectively. Cox proportional hazards models were used. The analysis period was defined as the time from the first measurement of PlGF and sFlt-1/PlGF ratio to the time of birth or censoring. MAIN OUTCOME MEASURES: The primary study outcome was overall PTB. The relative risks (RR) of birth within 1, 2 and 3 weeks and for medically indicated and spontaneous PTB were also ascertained. RESULTS: The early FGR cohort had lower median PlGF levels (54 versus 229 ng/L, p < 0.001) and higher median sFlt-1 levels (2774 ng/L versus 2096 ng/L, p < 0.001) and sFlt-1/PlGF ratio higher (35 versus 10, p < 0.001). Both PlGF <100 ng/L and elevated sFlt-1/PlGF ratio were strongly predictive for PTB as well as PTB within 1, 2 and 3 weeks of diagnosis. For both FGR and AGA groups, PlGF <100 ng/L or raised sFlt-1/PlGF ratio were strongly associated with increased risk for medically indicated PTB. The highest RR was seen in the FGR cohort when PlGF was <100 ng/L (RR 35.20, 95% CI 11.48-175.46). CONCLUSIONS: Low maternal PlGF levels and elevated sFlt-1/PlGF ratio are potentially useful to predict PTB in both FGR and AGA pregnancies.

Angiogenic imbalance in maternal and cord blood is associated with neonatal birth weight and head circumference in pregnancies with major fetal congenital heart defect.

OBJECTIVES: To ascertain whether abnormalities in neonatal head circumference and/or body weight are associated with levels of angiogenic/antiangiogenic factors in the maternal and cord blood of pregnancies with a congenital heart defect (CHD) and to assess whether the specific type of CHD influences this association. METHODS: This was a multicenter case-control study of women carrying a fetus with major CHD. Recruitment was carried out between June 2010 and July 2018 at four tertiary care hospitals in Spain. Maternal venous blood was drawn at study inclusion and at delivery. Cord blood samples were obtained at birth when possible. Placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng) were measured in maternal and cord blood. Biomarker concentrations in the maternal blood were expressed as multiples of the median (MoM). RESULTS: PlGF, sFlt-1 and sEng levels were measured in the maternal blood in 237 cases with CHD and 260 healthy controls, and in the cord blood in 150 cases and 56 controls. Compared with controls, median PlGF MoM in maternal blood was significantly lower in the CHD group (0.959 vs 1.022; P < 0.0001), while median sFlt-1/PlGF ratio MoM was significantly higher (1.032 vs 0.974; P = 0.0085) and no difference was observed in sEng MoM (0.981 vs 1.011; P = 0.4673). Levels of sFlt-1 and sEng were significantly higher in cord blood obtained from fetuses with CHD compared to controls (mean ± standard error of the mean, 447 ± 51 vs 264 ± 20 pg/mL; P = 0.0470 and 8.30 ± 0.92 vs 5.69 ± 0.34 ng/mL; P = 0.0430, respectively). Concentrations of sFlt-1 and the sFlt-1/PlGF ratio in the maternal blood at study inclusion were associated negatively with birth weight and head circumference in the CHD group. The type of CHD anomaly (valvular, conotruncal or left ventricular outflow tract obstruction) did not appear to alter these findings. CONCLUSIONS: Pregnancies with fetal CHD have an antiangiogenic profile in maternal and cord blood. This imbalance is adversely associated with neonatal head circumference and birth weight. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Maternal cardiovascular function in midgestation is related to placental angiogenesis.

OBJECTIVE: To investigate whether angiogenic markers of placental function are associated with maternal cardiac function and hemodynamic responses at 19-23 weeks' gestation, controlling for maternal risk factors and pregnancy complications. METHODS: This was a prospective study of women with singleton pregnancy attending King's College Hospital, London, UK, for a routine hospital visit at 19-23 weeks' gestation. We recorded maternal characteristics and measured mean arterial pressure (MAP), maternal heart rate, serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1). We also performed maternal echocardiography to assess cardiac output and peripheral vascular resistance as well as indices of diastolic and systolic function. RESULTS: Our cohort included 4006 women. Lower PlGF values were significantly associated with higher MAP (P < 0.0001), lower maternal heart rate (P < 0.0001), lower mitral valve s' mean velocity (P = 0.027) and higher left atrial area (P = 0.022) after adjustment for maternal characteristics and pregnancy complications. sFlt-1 was associated positively with relative wall thickness (P = 0.012), whereas sFlt-1/PlGF ratio was associated negatively with mitral valve A (P = 0.006) and positively with left atrial area (P = 0.015) and MAP (P = 0.004). The magnitude of these associations was similar in the subgroup of women without any risk factors based on their obstetric and medical history. CONCLUSIONS: A continuous association of moderate strength between angiogenic factors and subclinical maternal cardiac function alterations is present in midgestation, independently of pre-existing maternal risk factors and pregnancy complications. Impaired placental function appears to be related to mild systolic and diastolic dysfunction and cardiac remodeling. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Screening for pre-eclampsia by maternal serum glycosylated fibronectin and angiogenic markers at 36 weeks' gestation.

OBJECTIVES: First, to examine the predictive performance of maternal serum glycosylated fibronectin (GlyFn) at 35 + 0 to 36 + 6 weeks' gestation in screening for delivery with pre-eclampsia (PE) and delivery with gestational hypertension (GH) at ≥ 37 weeks' gestation, both within 3 weeks and at any time after the examination. Second, to compare the predictive performance for delivery with PE and delivery with GH of various combinations of biomarkers, including GlyFn, mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1). Third, to compare the predictive performance for delivery with PE and delivery with GH by serum PlGF concentration, sFlt-1/PlGF concentration ratio and the competing-risks model with different combinations of biomarkers as above. Fourth, to compare the predictive performance of screening at 11 + 0 to 13 + 6 weeks vs 35 + 0 to 36 + 6 weeks for delivery with PE and delivery with GH at ≥ 37 weeks' gestation. METHODS: This was a case-control study in which maternal serum GlyFn was measured in stored samples from a non-intervention screening study in singleton pregnancies at 35 + 0 to 36 + 6 weeks' gestation using a point-of-care device. We used samples from women who delivered at ≥ 37 weeks' gestation, including 100 who developed PE, 100 who developed GH and 600 controls who did not develop PE or GH. In all cases, MAP, UtA-PI, PlGF and sFlt-1 were measured during the routine visit at 35 + 0 to 36 + 6 weeks. We used samples from patients that had been examined previously at 11 + 0 to 13 + 6 weeks' gestation. Levels of GlyFn were transformed to multiples of the expected median (MoM) values after adjusting for maternal demographic characteristics and elements from the medical history. Similarly, the measured values of MAP, UtA-PI, PlGF and sFlt-1 were converted to MoM. The competing-risks model was used to combine the prior distribution of the gestational age at delivery with PE, obtained from maternal risk factors, with various combinations of biomarker MoM values to derive the patient-specific risks of delivery with PE. The performance of screening of different strategies was estimated by examining the detection rate (DR) at a 10% fixed false-positive rate (FPR) and McNemar's test was used to compare the DRs between the different methods of screening. RESULTS: The DR, at 10% FPR, of screening by the triple test (maternal risk factors plus MAP, PlGF and sFlt-1) was 83.7% (95% CI, 70.3-92.7%) for delivery with PE within 3 weeks of screening and 80.0% (95% CI, 70.8-87.3%) for delivery with PE at any time after screening, and this performance was not improved by the addition of GlyFn. The performance of screening by a combination of maternal risk factors, MAP, PlGF and GlyFn was similar to that of the triple test, both for delivery with PE within 3 weeks and at any time after screening. The performance of screening by a combination of maternal risk factors, MAP, UtA-PI and GlyFn was similar to that of the triple test, and they were both superior to screening by low PlGF concentration (PE within 3 weeks: DR, 65.3% (95% CI, 50.4-78.3%); PE at any time: DR, 56.0% (95% CI, 45.7-65.9%)) or high sFlt-1/PlGF concentration ratio (PE within 3 weeks: DR, 73.5% (95% CI, 58.9-85.1%); PE at any time: DR, 63.0% (95% CI, 52.8-72.4%)). The predictive performance of screening at 35 + 0 to 36 + 6 weeks' gestation for delivery with PE and delivery with GH at ≥ 37 weeks' gestation was by far superior to screening at 11 + 0 to 13 + 6 weeks. CONCLUSION: GlyFn is a potentially useful biomarker in third-trimester screening for term PE and term GH, but the findings of this case-control study need to be validated by prospective screening studies. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Evaluation of angiogenic factors in prediction of growth-related neonatal morbidity at term and comparison with competing-risks model.

OBJECTIVES: First, to describe the distribution of biomarkers of impaired placentation in small-for-gestational-age (SGA) pregnancies with neonatal morbidity; second, to examine the predictive performance for growth-related neonatal morbidity of a high soluble fms-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PlGF) ratio or low PlGF; and, third, to compare the performance of a high sFlt-1/PlGF ratio or low PlGF with that of the competing-risks model for SGA in predicting growth-related neonatal morbidity. METHODS: This was a prospective observational study of women attending for a routine hospital visit at 35 + 0 to 36 + 6 weeks' gestation in two maternity hospitals in England. The visit included recording of maternal demographic characteristics and medical history, an ultrasound scan and measurement of serum PlGF and sFlt-1. The primary outcome was delivery within 4 weeks after assessment and at < 42 weeks' gestation of a SGA neonate with birth weight < 10th or < 3rd percentile, combined with neonatal unit (NNU) admission for ≥ 48 h or a composite of major neonatal morbidity. The detection rates in screening by PlGF < 10th percentile, sFlt-1/PlGF ratio > 90th percentile, sFlt-1/PlGF ratio > 38 and the competing-risks model for SGA, using combinations of maternal risk factors and Z-scores of estimated fetal weight (EFW) with multiples of the median values of uterine artery pulsatility index, PlGF and sFlt-1, were estimated. The detection rates by the different methods of screening were compared using McNemar's test. RESULTS: In the study population of 29 035 women, prediction of growth-related neonatal morbidity at term provided by the competing-risks model was superior to that of screening by low PlGF concentration or a high sFlt-1/PlGF concentration ratio. For example, at a screen-positive rate (SPR) of 13.1%, as defined by the sFlt-1/PlGF ratio > 38, the competing-risks model using maternal risk factors and EFW predicted 77.5% (95% CI, 71.7-83.3%) of SGA < 10th percentile and 89.3% (95% CI, 83.7-94.8%) of SGA < 3rd percentile with NNU admission for ≥ 48 h delivered within 4 weeks after assessment. The respective values for SGA with major neonatal morbidity were 71.4% (95% CI, 56.5-86.4%) and 90.0% (95% CI, 76.9-100%). These were significantly higher than the respective values of 41.0% (95% CI, 34.2-47.8%) (P < 0.0001), 48.8% (95% CI, 39.9-57.7%) (P < 0.0001), 37.1% (95% CI, 21.1-53.2%) (P = 0.003) and 55.0% (95% CI, 33.2-76.8%) (P = 0.035) achieved by the application of the sFlt-1/PlGF ratio > 38. At a SPR of 10.0%, as defined by PlGF < 10th percentile, the competing-risks model using maternal factors and EFW predicted 71.5% (95% CI, 65.2-77.8%) of SGA < 10th percentile and 84.3% (95% CI, 77.8-90.8%) of SGA < 3rd percentile with NNU admission for ≥ 48 h delivered within 4 weeks after assessment. The respective values for SGA with major neonatal morbidity were 68.6% (95% CI, 53.1-83.9%) and 85.0% (95% CI, 69.4-100%). These were significantly higher than the respective values of 36.5% (95% CI, 29.8-43.2%) (P < 0.0001), 46.3% (95% CI, 37.4-55.2%) (P < 0.0001), 37.1% (95% CI, 21.1-53.2%) (P = 0.003) and 55.0% (95% CI, 33.2-76.8%) (P = 0.021) achieved by the application of PlGF < 10th percentile. CONCLUSION: At 36 weeks' gestation, the prediction of growth-related neonatal morbidity by the competing-risks model for SGA, using maternal risk factors and EFW, is superior to that of a high sFlt-1/PlGF ratio or low PlGF. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Ophthalmic artery Doppler and biomarkers of impaired placentation at 36 weeks' gestation in pregnancies with small fetuses.

OBJECTIVES: First, to compare ophthalmic artery peak systolic velocity (PSV) ratio and biomarkers of impaired placentation at 36 weeks' gestation in women who delivered a small-for-gestational-age (SGA) or growth-restricted (FGR) neonate, in the absence of hypertensive disorder, with those of women who developed pre-eclampsia (PE) or gestational hypertension (GH) and of women unaffected by SGA, FGR, PE or GH. Second, to examine the associations of PSV ratio, uterine artery pulsatility index (UtA-PI), placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) with birth-weight Z-score or percentile. METHODS: This was a prospective observational study of women with a singleton pregnancy attending for a routine hospital visit at 35 + 0 to 36 + 6 weeks' gestation. This visit included recording of maternal demographic characteristics and medical history, ultrasound examination of fetal anatomy and growth, and measurement of maternal ophthalmic artery PSV ratio, UtA-PI, PlGF and sFlt-1. Values of PSV ratio, UtA-PI, PlGF and sFlt-1 were converted to multiples of the median (MoM) or delta values. Median MoM or deltas of these biomarkers in the SGA, FGR, PE and GH groups were compared with those in the unaffected group. Regression analysis was used to examine the relationship of PSV ratio delta, UtA-PI MoM, PlGF MoM and sFlt-1 MoM with birth-weight Z-score, after exclusion of PE and GH cases. RESULTS: The study population of 9033 pregnancies included 7696 (85.2%) that were not affected by FGR, SGA, PE or GH, 182 (2.0%) complicated by FGR in the absence of PE or GH, 698 (7.7%) with SGA in the absence of FGR, PE or GH, 236 (2.6%) with PE and 221 (2.4%) with GH. Compared with unaffected pregnancies, in the FGR and SGA groups, the PSV ratio delta and sFlt-1 MoM were increased and PlGF MoM was decreased; UtA-PI MoM was increased in the FGR group but not the SGA group. The magnitude of the changes in biomarker values relative to the unaffected group was smaller in the FGR and SGA groups than that in the PE and GH groups. In non-hypertensive pregnancies, there were significant inverse associations of PSV ratio delta and UtA-PI MoM with birth-weight Z-score, such that the values were increased in small babies and decreased in large babies. There was a quadratic relationship between PlGF MoM and birth-weight Z-score, with low PlGF levels in small babies and high PlGF levels in large babies. There was no significant association between sFlt-1 MoM and birth-weight Z-score. CONCLUSIONS: Ophthalmic artery PSV ratio, reflective of peripheral vascular resistance, and UtA-PI, PlGF and sFlt-1, biomarkers of impaired placentation, are altered in pregnancies complicated by hypertensive disorder and, to a lesser extent, in non-hypertensive pregnancies delivering a SGA or FGR neonate. The associations between the biomarkers and birth-weight Z-score suggest the presence of a continuous physiological relationship between fetal size and peripheral vascular resistance and placentation, rather than a dichotomous relationship of high peripheral resistance and impaired placentation in small compared to non-small fetuses. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Maternal serum biomarkers of placental insufficiency at 24-28 weeks of pregnancy in relation to the risk of delivering small-for-gestational-age infant in Sylhet, Bangladesh: a prospective cohort study.

BACKGROUND: Small-for-gestational-age (SGA), commonly caused by poor placentation, is a major contributor to global perinatal mortality and morbidity. Maternal serum levels of placental protein and angiogenic factors are changed in SGA. Using data from a population-based pregnancy cohort, we estimated the relationships between levels of second-trimester pregnancy-associated plasma protein-A (PAPP-A), placental growth factor (PlGF), and serum soluble fms-like tyrosine kinase-1 (sFlt-1) with SGA. METHODS: Three thousand pregnant women were enrolled. Trained health workers prospectively collected data at home visits. Maternal blood samples were collected, serum aliquots were prepared and stored at -80℃. Included in the analysis were 1,718 women who delivered a singleton live birth baby and provided a blood sample at 24-28 weeks of gestation. We used Mann-Whitney U test to examine differences of the median biomarker concentrations between SGA (< 10th centile birthweight for gestational age) and appropriate-for-gestational-age (AGA). We created biomarker concentration quartiles and estimated the risk ratios (RRs) and 95% confidence intervals (CIs) for SGA by quartiles separately for each biomarker. A modified Poisson regression was used to determine the association of the placental biomarkers with SGA, adjusting for potential confounders. RESULTS: The median PlGF level was lower in SGA pregnancies (934 pg/mL, IQR 613-1411 pg/mL) than in the AGA (1050 pg/mL, IQR 679-1642 pg/mL; p < 0.001). The median sFlt-1/PlGF ratio was higher in SGA pregnancies (2.00, IQR 1.18-3.24) compared to AGA pregnancies (1.77, IQR 1.06-2.90; p = 0.006). In multivariate regression analysis, women in the lowest quartile of PAPP-A showed 25% higher risk of SGA (95% CI 1.09-1.44; p = 0.002). For PlGF, SGA risk was higher in women in the lowest (aRR 1.40, 95% CI 1.21-1.62; p < 0.001) and 2nd quartiles (aRR 1.30, 95% CI 1.12-1.51; p = 0.001). Women in the highest and 3rd quartiles of sFlt-1 were at reduced risk of SGA delivery (aRR 0.80, 95% CI 0.70-0.92; p = 0.002, and aRR 0.86, 95% CI 0.75-0.98; p = 0.028, respectively). Women in the highest quartile of sFlt-1/PlGF ratio showed 18% higher risk of SGA delivery (95% CI 1.02-1.36; p = 0.025). CONCLUSIONS: This study provides evidence that PAPP-A, PlGF, and sFlt-1/PlGF ratio measurements may be useful second-trimester biomarkers for SGA.

Prediction of preterm birth in women with fetal growth restriction - Is the weekly change in sFlt-1/PlGF ratio or PlGF levels useful?

INTRODUCTION: To assess the rate of change in soluble fms-like tyrosine kinase-1/placental growth factor (sFlt-1/PlGF) ratio and PlGF levels per week compared to a single sFlt-1/PlGF ratio or PlGF level to predict preterm birth for pregnancies complicated by fetal growth restriction. MATERIAL AND METHODS: A prospective cohort study of pregnancies complicated by isolated fetal growth restriction. Maternal serum PlGF levels and the sFlt-1/PlGF ratio were measured at 4-weekly intervals from recruitment to delivery. We investigated the utility of PlGF levels, sFlt-1/PlGF ratio, change in PlGF levels per week or sFlt-1/PlGF ratio per week. Cox-proportional hazard models and Harrell's C concordance statistic were used to evaluate the effect of biomarkers on time to preterm birth. RESULTS: The total study cohort was 158 pregnancies comprising 91 (57.6%) with fetal growth restriction and 67 (42.4%) with appropriate for gestational age controls. In the fetal growth restriction cohort, sFlt-1/PlGF ratio and PlGF levels significantly affected time to preterm birth (Harrell's C: 0.85-0.76). The rate of increase per week of the sFlt-1/PlGF ratio (hazard ratio [HR] 3.91, 95% confidence interval [CI]: 1.39-10.99, p = 0.01, Harrell's C: 0.74) was positively associated with preterm birth but change in PlGF levels per week was not (HR 0.65, 95% CI: 0.25-1.67, p = 0.37, Harrell's C: 0.68). CONCLUSIONS: Both a high sFlt-1/PlGF ratio and low PlGF levels are predictive of preterm birth in women with fetal growth restriction. Although the rate of increase of the sFlt-1/PlGF ratio predicts preterm birth, it is not superior to either a single elevated sFlt-1/PlGF ratio or low PlGF level.

Stability of serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase 1 (sFlt-1).

Placental growth factor (PlGF) and soluble fms-like tyrosine kinase 1 (sFlt-1) are biomarkers used for diagnosis and risk estimation of preeclampsia. Stability in room temperature (RT) may affect the usefulness of these analyses, as shipping at ambient temperature is the most practical and suitable way to ship samples. To date, scientific studies of such stability are lacking. We aimed to assess the stability of PlGF and sFlt-1 at RT in serum from pregnant women. In addition, a smaller study of stability at 4 °C was performed. Serum was collected from 69 pregnant women and stored at RT or at 4 °C for up to 192 h. Analytes were considered stable if the mean percent change ± 90 confidence interval of the mean was within the baseline concentration ± allowable bias. Allowable bias was calculated from data on biological variation. In addition, an instability equation was calculated to assess loss of stability, in line with recent European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) recommendations. The mean percent change was <3.5% for PlGF, <1% for sFlt-1 and <4.5% for sFlt-1/PlGF ratio up to 192 h. PlGF was considered stable for 168 h, and sFlt-1 and sFlt-1/PlGF ratios were considered stable for 192 h at RT. At 4 °C, PlGF was considered stable for 120 h, sFlt-1 for 168 h and sFlt-1/PlGF ratio for 120 h. Both PlGF and sFlt-1 as well as sFlt-1/PlGF ratio show sufficient stability (minimum 168 h) for samples to be shipped at RT.

Association of angiogenic factors (placental growth factor and soluble FMS-like tyrosine kinase-1) in preeclamptic women of African ancestry comorbid with HIV infection.

BACKGROUND: Preeclampsia is a significant cause of maternal and fetal morbidity and mortality, particularly in low- and middle-income countries like South Africa. AIM: The aim of our study was to investigate the association between placental growth factor (PlGF) and soluble FMS-like tyrosine kinase-1 (sFlt-1) in South African preeclamptic women of African ancestry, comorbid with HIV infection. METHODS: The study population consisted of women attending a regional hospital in Durban, South Africa, stratified by pregnancy type (normotensive pregnant and preeclampsia) and HIV status. Preeclampsia was defined as new-onset hypertension and proteinuria. DNA was obtained from whole blood. The SNPs of interest were rs722503 in sFlt-1 and rs4903273 in PlGF. RESULTS: Our findings suggest that single nucleotide polymorphisms of rs722503 analysis show no significant associations between the genotypic frequencies of rs722503 variants and preeclampsia risk in either HIV-negative or HIV-positive groups of women of African ancestry. Similarly, the rs493273 polymorphism showed no significant association with preeclampsia risk in either HIV-negative or HIV-positive pregnant women. Additionally, comparisons of dominant, recessive, and over-dominant allele models did not reveal significant associations. These findings suggest that these genetic variants may not significantly contribute to preeclampsia development in this African ancestry population. However, significant differences were observed in the rs4903273 genotype frequencies between normotensive and preeclamptic women, regardless of HIV status, over dominant alleles AA + GG vs AG showed a significant difference [OR = 2.706; 95% Cl (1.199-5.979); adjusted p = 0.0234*], also in normotensive compared to EOPE (OR = 2.804; 95% Cl (1.151-6.89) p = 0.0326* and LOPE (OR = 2.601; 95% Cl (1.0310-6.539) p = 0.0492*), suggesting that they may be the potential role of this variant in preeclampsia susceptibility. CONCLUSION: The findings suggest that the rs722503 and rs493273 polymorphisms do not significantly contribute to preeclampsia susceptibility in HIV-negative or HIV-positive pregnant women. However, the rs4903273 genotype frequencies showed notable differences between normotensive and preeclamptic women, indicating a potential association with preeclampsia development in the African ancestry population irrespective of HIV status.

Increased Expression Levels of Soluble Fms-Like Tyrosine Kinase-1 Inhibit the Development of the Nervous System.

INTRODUCTION: Preeclampsia (PE) remains a leading cause of maternal and perinatal morbidity. At present, only limited options are available for the treatment of PE. Consequently, many patients need to terminate their pregnancies to relieve the disease. Soluble fms-like tyrosine kinase-1 (sFlt-1) is a decoy receptor of placental growth factor and vascular endothelial growth factor which can promote angiogenesis. Throughout pregnancy, the expression level of sFlt-1 continues to increase in both the mother with PE and her offspring. MATERIAL AND METHODS: In this experiment, we generated a zebrafish line expressing high levels of sFlt-1 and investigated changes in behavior and development of the nervous system. RESULTS: At 96 h post-fertilization (hpf), the brain volume area of zebrafish in the experimental group (zFLT1+CasRx) was significantly smaller after injection than in the WT group (p < 0.05) and the negative control group (CasRx) (p < 0.05). At 96 hpf, compared with the WT group, the cerebral blood vessels in the CasRx control group and experimental group (zFLT1-sgRNA+CasRx) were significantly lower after injection (p < 0.05). Compared with the CasRx control group, the track movement distance and the mean track speed of zebrafish in the experimental group (zFLT1-sgRNA+CasRx) after the 6th injection were significantly decreased (p < 0.05). CONCLUSIONS: The increased expression levels of sFlt-1 in zebrafish inhibited the development of the cerebral blood vessels, influenced brain volumes, and inhibited behavioral activities. Our data suggest that the elevation of sFlt-1 in the pathological state of PE can inhibit the development of the nervous system in offspring.

Preeclampsia at term can be classified into 2 clusters with different clinical characteristics and outcomes based on angiogenic biomarkers in maternal blood.

BACKGROUND: An antiangiogenic state has emerged as a mechanism of disease in preeclampsia. Angiogenic biomarkers are used in the risk assessment of this syndrome, particularly of early disease. The role of an antiangiogenic state in late preeclampsia is unclear. OBJECTIVE: This study aimed to determine the prevalence, characteristics, and clinical significance of angiogenic/antiangiogenic factor abnormalities in women with preeclampsia stratified according to gestational age at delivery. STUDY DESIGN: Two studies were conducted: (1) a longitudinal nested case-control study comprising women with preeclampsia (n=151) and a control group (n=540); and (2) a case series of patients with preeclampsia (n=452). In patients with preeclampsia, blood was collected at the time of diagnosis. Plasma concentrations of placental growth factor and soluble fms-like tyrosine kinase-1 were determined by enzyme-linked immunosorbent assays. An abnormal angiogenic profile was defined as a plasma ratio of placental growth factor and soluble fms-like tyrosine kinase-1 expressed as a multiple of the median <10th percentile for gestational age based on values derived from the longitudinal study. The proportion of patients diagnosed with preeclampsia who had an abnormal angiogenic profile was determined in the case-series participants and stratified by gestational age at delivery into early (≤34 weeks), intermediate (34.1-36.9 weeks), and term (≥37 weeks) preeclampsia. The demographics, clinical characteristics, and pregnancy outcomes of women with preeclampsia with and without an abnormal angiogenic profile were compared. RESULTS: The prevalence of an abnormal angiogenic profile was higher in preterm than in term preeclampsia (for early, intermediate, and term in the case-control study: 90%, 100%, and 39%; for the case series: 98%, 80%, and 55%, respectively). Women with preeclampsia at term who had an abnormal angiogenic profile were more frequently nulliparous (57% vs 35%), less likely to smoke (14% vs 26%), at greater risk for maternal (14% vs 5%) or neonatal (7% vs 1%) complications, and more often had placental lesions consistent with maternal vascular malperfusion (42% vs 23%; all, P<.05) than those without an abnormal profile. Women with preeclampsia at term who had a normal angiogenic profile had a higher frequency of chronic hypertension (36% vs 21%) and were more likely to have class ≥2 obesity (41% vs 23%) than those with an abnormal profile (both, P<.05). CONCLUSION: Patients with early preeclampsia had an abnormal angiogenic profile in virtually all cases, whereas only 50% of women with preeclampsia at term had such abnormalities. The profile of angiogenic biomarkers can be used to classify patients with preeclampsia at term, on the basis of mechanisms of disease, into 2 clusters, which have different demographics, clinical characteristics, and risks of adverse maternal and neonatal outcomes. These findings provide a simple approach to classify preeclampsia at term and have implications for future clinical care and research.

Angiogenic imbalance in pre-eclampsia and fetal growth restriction: enhanced soluble fms-like tyrosine kinase-1 binding or diminished production of placental growth factor?

OBJECTIVES: To assess levels of total placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1) and free PlGF in women with pre-eclampsia (PE) with or without a small-for-gestational-age (SGA) neonate in order to establish whether low free PlGF levels associated with PE and SGA are due to enhanced sFlt-1 binding or decreased PlGF production. METHODS: This was a secondary analysis of a prospective multicenter cohort study involving 407 pregnancies with suspected or confirmed PE, in which total PlGF levels were calculated from measured sFlt-1 and free PlGF levels. The control group included women who were suspected to have PE at a certain point in pregnancy but did not develop PE. The analysis was stratified according to whether PE was early- or late-onset (gestational age < 34 weeks vs ≥ 34 weeks) and according to the presence of SGA at birth, which was used as a proxy of fetal growth restriction in the absence of Doppler ultrasound and biometric data. RESULTS: In early-onset PE, both women with and those without SGA had lower free (19 and 45 pg/mL) and total (44 and 100 pg/mL) PlGF levels compared with women without PE (free and total PlGF, 300 and 381 pg/mL, respectively). SGA alone did not affect free and total PlGF in this condition (free and total PlGF, 264 and 352 pg/mL, respectively). Observations in women with late-onset PE were similar, although the changes were more modest. Both SGA (gestational age < 34 weeks) and PE were individually associated with increased sFlt-1 and, in women with both PE and SGA, the upregulation of sFlt-1 occurred in a synergistic manner, thus resulting in the highest sFlt-1/free PlGF ratio in this group. This occurred in both early- and late-onset PE. CONCLUSIONS: Particularly in pregnancies with early-onset PE and SGA, diminished PlGF production is an important cause of low free PlGF levels. Under such conditions, sFlt-1 lowering is unlikely to restore the angiogenic balance. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Prediction using serum glycosylated fibronectin and angiogenic factors of superimposed pre-eclampsia in women with chronic hypertension.

OBJECTIVE: To compare the predictive performance for delivery with pre-eclampsia (PE) within 2 weeks of assessment in women with chronic hypertension at 24-41 weeks' gestation between serum glycosylated fibronectin (GlyFn) concentration, serum placental growth factor (PlGF) concentration and soluble fms-like tyrosine kinase-1 (sFlt-1) to PlGF concentration ratio. METHODS: This was a prospective study of 104 women with a singleton pregnancy and chronic hypertension presenting at 24-41 weeks' gestation. Twenty-six (25.0%) cases developed superimposed PE within 2 weeks of sampling. We compared the predictive performance for superimposed PE between GlyFn, PlGF and the sFlt-1/PlGF ratio at a fixed screen-positive rate of approximately 10%. RESULTS: The median gestational age at sampling was 34.1 (interquartile range, 31.5-35.6) weeks and 84.6% (88/104) of cases were sampled at < 36 weeks. The predictive performance for superimposed PE of the three methods of screening was similar, with detection rates of about 23-27%, at a screen-positive rate of 11% and a false-positive rate of about 5%. CONCLUSIONS: Measurement of GlyFn is a simple point-of-care test that can be carried out without need for a laboratory and provide results within 10 min of testing. In this respect, it could potentially replace the angiogenic markers that are used currently in the prediction of imminent PE in high-risk women. However, neither GlyFn nor angiogenic factors are likely to improve the management of women with chronic hypertension because their predictive performance for superimposed PE is poor. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Prediction using serum glycosylated fibronectin of imminent pre-eclampsia in women with new-onset hypertension.

OBJECTIVE: To compare the predictive performance for delivery with pre-eclampsia (PE) within 2 weeks after assessment in women with new-onset hypertension at 24-41 weeks' gestation between serum glycosylated fibronectin (GlyFn) concentration, serum placental growth factor (PlGF) concentration and soluble fms-like tyrosine kinase-1 (sFlt-1) to PlGF concentration ratio. METHODS: This was a prospective observational study of 409 women with a singleton pregnancy presenting at 24-41 weeks' gestation with new-onset hypertension. The recommended cut-off for sFlt-1/PlGF ratio for the prediction of PE in the platform used in this study is 85; the appropriate cut-offs for GlyFn and PlGF were determined to achieve the same screen-positive rate as that of sFlt-1/PlGF ratio > 85. We then compared the predictive performance for delivery with PE within 2 weeks after presentation between GlyFn, PlGF and sFlt-1/PlGF, both overall and in subgroups according to gestational age at presentation. RESULTS: Delivery with PE within 2 weeks occurred in 93 (22.7%) cases. The screen-positive rate for sFlt-1/PlGF ratio > 85 was 46.2%. The cut-off corresponding to a screen-positive rate of 46.2% was 75 pg/mL for PlGF and 510 µg/mL for GlyFn. The overall detection rate for delivery with PE within 2 weeks after presentation was 62.4% (95% CI, 51.7-72.2%) for GlyFn and sFlt-1/PlGF and 60.2% (95% CI, 49.5-70.2%) for PlGF. In all women who delivered with PE within 2 weeks after presentation at < 34 weeks' gestation and in about 60-70% of those presenting at < 38 weeks, GlyFn and sFlt-1/PlGF were increased and PlGF was reduced. However, the screen-positive rate for these tests was very high at about 45%. The predictive performance for delivery with PE within 2 weeks after presentation at ≥ 38 weeks' gestation was poorer for all three methods of screening, with detection rates of 47-63% at screen-positive rates of 40-50%. CONCLUSIONS: In women with new-onset hypertension, the predictive performance for delivery with PE within 2 weeks after presentation for serum GlyFn is similar to that of PlGF and the sFlt-1/PlGF ratio, but GlyFn may be the preferred option because it is a rapid point-of-care test. However, the predictive performance for all tests is relatively poor. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Prediction of hypertensive disorders after screening at 36 weeks' gestation: comparison of angiogenic markers with competing-risks model.

OBJECTIVE: To compare the performance at 35 + 0 to 36 + 6 weeks' gestation of screening for delivery with pre-eclampsia (PE) at various timepoints, using one of three approaches: placental growth factor (PlGF) concentration, soluble fms-like tyrosine kinase-1 (sFlt-1) to PlGF concentration ratio, or the competing-risks model, which combines maternal risk factors with biomarkers to estimate patient-specific risk. METHODS: This was a prospective observational study of women attending for a routine hospital visit at 35 + 0 to 36 + 6 weeks' gestation at one of two maternity hospitals in England between 2016 and 2022. During the visit, maternal demographic characteristics and medical history were recorded and serum PlGF, serum sFlt-1 and mean arterial pressure (MAP) were measured. Detection rates (DRs) were evaluated for delivery with PE (defined as per American College of Obstetricians and Gynecologists 2019 criteria) within 1 week, within 2 weeks or at any time after screening, using the following strategies: (i) low PlGF (< 10th percentile); (ii) high sFlt-1/PlGF ratio (> 90th percentile); or (iii) the competing-risks model, in which maternal factors were combined with multiples of the median values of PlGF ('single test'), PlGF and sFlt-1 ('double test') or PlGF, sFlt-1 and MAP ('triple test'). Risk cut-offs corresponded to a screen-positive rate of 10%. DRs were compared between tests. RESULTS: Of 34 782 pregnancies, 831 (2.4%) developed PE. In screening for delivery with PE at any time from assessment, the DR at 10% screen-positive rate was 47% by low PlGF alone, 54% by the single test, 55% by high sFlt-1/PlGF ratio, 61% by the double test and 68% by the triple test. In screening for delivery with PE within 2 weeks from assessment, the respective values were 67%, 74%, 74%, 80% and 87%. In screening for delivery with PE within 1 week from assessment, the respective values were 77%, 81%, 85%, 88% and 91%. For prediction of PE at any time, the DR was significantly higher with the triple test compared to PlGF alone or the sFlt-1/PlGF ratio, with a DR difference (95% CI) of 20.1% (16.7-23.0%) and 12.4% (9.7-15.3%), respectively. Similar results were seen for prediction of PE within 2 weeks (20.6% (14.9-26.8%) and 12.9% (7.7-17.5%), respectively) and prediction of PE within 1 week (13.5% (5.4-21.6%) and 5.4% (0.0-10.8%), respectively). The double test was superior to the sFlt-1/PlGF ratio and the single test was superior to PlGF alone in the prediction of PE within 2 weeks and at any time from assessment, but not within 1 week of assessment. CONCLUSION: At 35 + 0 to 36 + 6 weeks' gestation, the performance of screening for PE by the competing-risks model triple test is superior to that of PlGF alone or the sFlt-1/PlGF ratio for the development of disease within 1 week, within 2 weeks and at any time from screening. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Prognostic value of angiogenic markers in pregnancies with fetal growth restriction.

OBJECTIVE: Pregnancies with fetal growth restriction are at increased risk of preeclampsia. Angiogenic markers including soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) are altered in pregnancies complicated by fetal growth restriction (FGR). The utility of these markers as a predictor of preeclampsia in women with growth-restricted fetuses is still uncertain. This study aims to evaluate the prognostic value of angiogenic markers for predicting the development of preeclampsia in pregnancies with FGR and suspected preeclampsia. METHODS: This study included 93 women with FGR, defined according to Delphi consensus criteria, who were assessed for angiogenic markers sFlt-1 and PlGF for suspicion of preeclampsia at the Department of Obstetrics and feto-maternal Medicine at the Medical University of Vienna between 2013 and 2020. Women with established diagnosis of preeclampsia at sampling were excluded. Cox regression analysis and logistic regression were performed to demonstrate the association of angiogenic markers with the outcome. RESULTS: Within this cohort, 14 women (15.1%) developed preeclampsia within one week from sampling, 21 (22.6%) within two weeks, 38 (40.9%) at any time. The sFLT-1/PLGF ratio consistently showed a stronger association with development of preeclampsia compared to sFlt-1 or PlGF alone in pregnancies with fetal growth restriction (PE within a week, AUC 0.85 vs 0.82 and 0.72, respectively). Models including sFlt-1/PlGF were more strongly associated with preeclampsia hazard compared to sFlt-1 and PlGF alone models (C-index: 0.79±0.046 vs 0.76±0.048 and 0.75±0.047, respectively). Risk classification capabilities of sFlt-1/PlGF decreased after the two-week time point. The established cut-off value for ruling out preeclampsia (sFlt-1/PlGF ratio <38) was effective with a negative predictive value of 93.3% and sensitivity of 95.2%. CONCLUSION: Combined use of sFlt-1/PlGF can be preferred to PlGF alone in pregnancies with fetal growth restriction. Moreover, established cut-offs for ruling-out development of preeclampsia seem to be effective in these patients. This article is protected by copyright. All rights reserved.