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.