Diagnostic accuracy of placental growth factor and ultrasound parameters to predict the small-for-gestational-age infant in women presenting with reduced symphysis-fundus height

Objectives To assess the diagnostic accuracy of placental growth factor (PlGF) and ultrasound parameters to predict delivery of a small-for-gestational-age (SGA) infant in women presenting with reduced symphysis-fundus height (SFH). Methods This was a multicenter prospective observational study recruiting 601 women with a singleton pregnancy and reduced SFH between 24 and 37 weeks' gestation across 11 sites in the UK and Canada. Plasma PlGF concentration < 5th centile, estimated fetal weight (EFW) < 10th centile, umbilical artery Doppler pulsatility index > 95th centile and oligohydramnios (amniotic fluid index < 5 cm) were compared as predictors for a SGA infant < 3rd customized birth-weight centile and adverse perinatal outcome. Test performance statistics were calculated for all parameters in isolation and in combination. Results Of the 601 women recruited, 592 were analyzed. For predicting delivery of SGA < 3rd centile (n = 78), EFW < 10th centile had 58% sensitivity (95% CI, 46-69%) and 93% negative predictive value (NPV) (95% CI, 90-95%), PlGF had 37% sensitivity (95% CI, 27-49%) and 90% NPV (95% CI, 87-93%); in combination, PlGF and EFW < 10th centile had 69% sensitivity (95% CI, 55-81%) and 93% NPV (95% CI, 89-96%). The equivalent receiver-operating characteristics (ROC) curve areas were 0.79 (95% CI, 0.74-0.84) for EFW < 10th centile, 0.70 (95% CI, 0.63-0.77) for low PlGF and 0.82 (95% CI, 0.77-0.86) in combination. Conclusions For women presenting with reduced SFH, ultrasound parameters had modest test performance for predicting delivery of SGA < 3rd centile. PlGF performed no better than EFW < 10th centile in determining delivery of a SGA infant.