AbstractsBiology & Animal Science

Currently there is no test to accurately predict stillbirth. It is proposed that better identification of placental disease in utero may aid stillbirth prediction and prevention. Pregnancies complicated by reduced fetal movement (RFM) have increased risk of stillbirth. We hypothesised that RFM is a symptom of placental dysfunction associated with adverse pregnancy outcome (APO) and that this placental abnormality can be detected antenatally and used to identify fetuses at highest-risk of APO. We tested this hypothesis by: 1) comparison of ex vivo placental structure and function between APO RFM pregnancies and their normal outcome RFM counterparts, 2) comparison of in utero estimates of placental size, vascularity, vascular and endocrine functions obtained from placental ultrasound, Doppler waveform analysis and maternal circulating placentally-derived hormone concentrations, to their ex vivo correlates and 3) examination of the predictive potential of placental biomarkers at the time of RFM.Ex vivo placentas from APO RFM pregnancies, compared to normal outcome RFM counterparts, were smaller (diameter, area, weight and volume, p<0.0001), less vascular (vessel number and density, p≤0.002), with arteries that were less responsive to sodium nitroprusside (p<0.05), and with aberrant endocrine function (reduced tissue content and/or release of human chorionic gonadotrophin (hCG), human placental lactogen (hPL) and soluble fms-like Tyrosine Kinase-1 (sFlt-1), p<0.03). Placental volume (PV) ex vivo correlated with sonographic estimated PV (p<0.004), hPL, hCG and placental growth factor (PlGF) concentrations in the maternal circulation (p<0.03). Ex vivo villous vessel number and density correlated with Doppler impedance at the umbilical artery free-loop (UAD-F, p=0.02) and intraplacental arteries (p<0.0001) respectively, whilst UAD-F impedance correlated with arterial thromboxane sensitivity (p<0.04). Examination of placental structure and function at the time of presentation with RFM identified 15 independently-predictive biomarkers. Three potential predictive models, incorporating measures of placental size (PlGF), endocrine function (sFlt-1), arterial thromboxane sensitivity and villous vascularity (UAD-F), were proposed. Using these models, sensitivity for APO was improved from 8.9% with baseline care (assessment of fetal size and gestation) to up to 37.5% at a fixed specificity of 99% (p<0.05). This series of studies shows that antenatal placental examination is possible and improves identification of pregnancies at highest risk of stillbirth in a high-risk population by up to 29%. Therefore such tests merit further development to prospectively assess their ability to predict and prevent stillbirth itself. Stillbirth (the death of an infant before birth) occurs in one in every 250-300 pregnancies after 28 weeks of pregnancy in high-income countries. There is currently no good test to predict and prevent this. Stillbirth is associated with disease of the placenta (afterbirth) in six in every ten cases. It is proposed…