PAPPA (Pregnancy Associated Protein A) is an indicator for Down’s syndrome screening during pregnancy, with normal values ranging from 0.42 to 2.5, with high values causing no major problems, while lower values indicate a high chance of Down’s syndrome and a higher risk. PAPPA is secreted by the placenta and meconium during pregnancy, and its value increases as the gestational cycle increases. PAPPA is checked in two stages, the first at 7 to 13 weeks in early pregnancy and the second at 14 to 20 weeks in mid-pregnancy. The concentration of PAPPA in the maternal blood of patients with Down’s syndrome and trisomy 18 is significantly lower, mostly below 0.44; whereas the normal maternal blood PAPPA value is usually above 1.0, so a low PAPPA value indicates a higher risk of Down’s syndrome. However, a positive PAPPA test alone does not confirm the diagnosis of Down syndrome, and a low PAPPA test is recommended for further amniocentesis or non-invasive DNA testing to rule out fetal malformations.