In the first trimester screen, what does low PAPP-A indicate?

Low levels of pregnancy-associated plasma protein A (PAPP-A) during the first trimester screening are associated with an increased risk for certain chromosomal abnormalities, particularly Trisomy 21, which is also known as Down syndrome. PAPP-A is a glycoprotein produced by the placenta and is measured in conjunction with other markers like free beta-human chorionic gonadotropin (hCG) to assess the risk of fetal aneuploidy.

When PAPP-A levels are low, it raises concern for the potential presence of chromosomal issues, particularly in conjunction with other abnormal markers. This is due to the fact that decreased levels of PAPP-A have been linked not only to Trisomy 21 but also to other conditions such as Trisomy 18 and the possibility of placental insufficiency. It’s important to note that while low PAPP-A can indicate a higher risk for these conditions, it is not diagnostic.

Normal fetal development would typically correlate with average or elevated PAPP-A levels, while low PAPP-A is indicative of a potential abnormality. Similarly, low PAPP-A does not suggest low risk for genetic disorders; in fact, it raises concern for several. Turner syndrome risk is influenced by other factors