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.

Assessment of left ventricular function using the Myocardial Performance Index in term fetuses that develop intrapartum compromise.

OBJECTIVE: To investigate the relationship between the prelabour left ventricular Myocardial Performance Index (LVMPI) and intrapartum fetal compromise (IFC) in low-risk term pregnancies. METHODS: A blinded, prospective observational cohort study at the Mater Mother's Hospital, Brisbane, Australia. A cohort of 284 women with uncomplicated singleton pregnancies underwent fortnightly ultrasound from 36 weeks until delivery. The LVMPI was assessed by conventional Doppler ultrasound and correlated with intrapartum outcomes. The LVMPI was also correlated with other Doppler indices of fetal wellbeing. RESULTS: Two hundred and seventy-three women were included in the final analysis, the median LVMPI was higher in fetuses that required any emergency operative delivery for IFC (0.56, 0.52-0.60 versus 0.54, 0.50-0.58, p = .007). The left ventricular cardiac output (LVCO) and cerebroplacental ratio (CPR) were lower in fetuses that required any emergency operative delivery for IFC compared to those that did not (164 ± 19 ml/min/kg versus 181 ± 30 ml/min/kg, p < .001) (1.63 + 0.30 versus 1.90 + 0.50, p < .001), respectively. The LVMPI was inversely correlated with the CPR (r = -0.20, p < .01), MCA PI (r = -0.29, p < .01), and LVCO (r = -0.22, p < .01). CONCLUSIONS: Higher global LVMPI is associated with a higher risk for IFC and poorer condition of the newborn.

Prelabour myocardial deformation and cardiac output in fetuses that develop intrapartum compromise at term: a prospective observational study.

Objective: Redistribution of cardiac output is responsible for the "brain sparing" effect seen during periods of acute or chronic fetal stress. We investigated the relationship between prelabour cardiac function in fetuses that subsequently developed intrapartum fetal compromise (IFC). Methods: A blinded, prospective, observational, cohort study, at Mater Mother's Hospital, Brisbane, Australia. A cohort of 284 women with uncomplicated singleton pregnancies underwent ultrasound every 2 weeks from 36 weeks until delivery. Fetal cardiac output was assessed by conventional Doppler ultrasound and myocardial deformation was measured using velocity vector imaging. Results: Two hundred and seventy three women were included in the final analysis, of which 19% had an emergency operative delivery for intrapartum fetal compromise (IFC). Global left ventricular strain (-12.1%, interquartile ranges (IQR) - 10.3 to -14% versus 13%, IQR -11.3 to -14.2%, p = .01) and strain rate (-1.00, IQR 0.85-1.16 s-1 versus -1.11, IQR -1.00 to -1.21 s-1, p < .001) were lower in fetuses that required any emergency operative delivery for IFC compared to those that did not. Global longitudinal right ventricular strain rate was lower in fetuses that developed IFC (-1.04 ± 0.22 s-1 versus 1.13 ± 0.22 s-1, p < .001), whereas global right ventricular strain did not show any significance differences between the two groups. Additionally, left ventricular cardiac output was lower in fetuses that developed IFC or had a composite neonatal morbidity (560 ± 44 mL/min versus 617 ± 72 mL/min, p < .001) or (581 ± 44 mL/min versus 612 ± 72 mL/min, p < .01), respectively. Conclusion: Lower global left ventricular strain and strain rate and cardiac output are associated with IFC and poorer condition of the newborn. Assessment of fetal cardiac function may be useful for risk stratification for intrapartum fetal compromise in apparently "low risk" term pregnancies.

Screening for adverse perinatal outcomes: uterine artery Doppler, cerebroplacental ratio and estimated fetal weight in low-risk women at term.

OBJECTIVE: To stratify apparently low-risk pregnant women into those who are at risk of adverse perinatal outcomes. Appropriate stratification would allow targeted prenatal and intrapartum management. METHODS: This prospective, observational study included normotensive women with appropriately grown, non-anomalous, singleton pregnancies. Participants underwent fortnightly ultrasounds from 36 weeks' gestation and intrapartum and neonatal outcomes were recorded. The association between uterine artery pulsatility index (UtA-PI), the cerebroplacental ratio (CPR) and estimated fetal weight (EFW) were explored along with their screening performance for CS-IFC and CNM. RESULTS: The final cohort included 429 women. As continuous variables, UtA-PI and the CPR were not correlated (rho = -0.05, p = .33). UtA-PI >95th centile and the CPR <10th centile were predictive of CS-IFC and CNM, with the highest sensitivity achieved by their combination (33.3%, 95% CI 11.6-55.1) for a false positive rate (FPR) of 15.8% (12.3-19.3). For CNM, the highest sensitivity (28.4%, 95% CI 18.6-38.2) and corresponding FPR (17.0%, 95% CI 13.0-20.9) was achieved by combining UtA-PI 95th centile, the CPR 10th centile and EFW 10th centile. EFW was the weakest of the three predictors. CONCLUSION: In this population, UtA-PI 95th centile and the CPR 10th centile have modest screening performance for CS-IFC and CNM.