Maternal serum placental growth factor and α‐fetoprotein testing in first trimester screening for Down syndrome

Abstract

The aim of this research was to evaluate the addition of first trimester maternal serum placental growth factor (PlGF) and α-fetoprotein (AFP) to the combined test for Down syndrome and a serum only protocol of PlGF, AFP, free β-human chorionic gonadotropin and pregnancy-associated plasma protein-A. Samples were from 92 Down syndrome cases with 552 matched controls. All women had a combined test at 11-14 weeks gestation. PlGF and AFP were measured and expressed in multiples of the gestation-specific median (MoM), adjusting for maternal weight and smoking status. Multivariate Gaussian modeling was used to predict detection and false-positive rates. The median PlGF level in the cases was 0.694 MoM and controls 1.000 MoM (p = <0.0001). The corresponding values for AFP were 0.764 MoM and 0.990 MoM (p < 0.0001). Statistical modeling predicted that for a given false-positive rate, the addition of PlGF to the combined test increases the detection rate by 4-7%. For a given detection rate, the false-positive rate could be almost halved. When both PlGF and AFP are used, the detection rate increase is 5-8%. A serum only protocol had a predicted a detection rate of 71% for a false-positive rate of 5%. Results suggest a substantial benefit of adding PlGF to the combined test.