PAPP-A stands for pregnancy associated plasma protein A. It is a proteing which is found in the maternal blood. Like bHCG, it comes from the placenta and its levels change with advancing pregnancy. In Down syndrome pregnancies, the levels tend to be lower than usual. It is used to predict the risk of Down syndrome, in combination with the maternal BHCG levels, maternal age and the nuchal translucency thickness.
This is a defect of metabolism occurring in about one in 10,000 babies. If untreated , it results in intellectual disability of the baby. These days we have early detection through routine newborn screening tests in the first few days of life. If a baby is found to be affected it is put on a special diet and he or she can then be expected to develop normally.
Polyhydramnios is refers to the situation where there is excess amniotic fluid for the stage of pregnancy. It is best detected with ultrasound examination. It occurs in about 1% of all pregnancies. It is particularly common in diabetes mellitus and in obese women. In about 20% of cases it is associated with a serious fetal abnormality, where the ingestion of amniotic fluid by the fetus is obstructed.