PAPP-A
Pregnancy-associated plasma protein A (PAPP-A) is a large placenta-derived glycoprotein. It is produced in high concentrations by the trophoblast during pregnancy and released into maternal circulation. PAPP-A determination in the first trimester contributed to enhanced sensitivity and specificity of prenatal congenital malformation screening. The optimal gestation age for the determination of screening of congenital malformations PAPP-A is between weeks 10th and 13th of the pregnancy.