Final answer:
The PAPP-A test is for Trisomy 21 and is carried out in the first trimester. A high result indicates a higher risk of the fetus having Trisomy 21, which increases with maternal age.
Step-by-step explanation:
The PAPP-A test for Trisomy 21 is conducted during the first trimester of pregnancy. If a person receives a high result from this screening, it indicates a higher risk for the fetus having Trisomy 21, also known as Down syndrome. The incidence of having a fetus with Trisomy 21 increases dramatically with the maternal age, specifically after the mother's age reaches 30 and even more so after 35. The PAPP-A test is part of the prenatal screening process to assess the risk of chromosomal abnormalities.