How Common Is Hdn

HDN is relatively uncommon in the United States due to advances in early detection and treatment, limiting it to approximately 4,000 cases a year. It is more likely to happen during a mother’s second or subsequent pregnancy. There are two causes, Rh incompatibility

What is the most common cause of HDN?

HDN most frequently occurs when an Rh negative mother has a baby with an Rh positive father. When the baby’s Rh factor is positive, like the father’s, problems can develop if the baby’s red blood cells cross to the Rh negative mother. This usually happens at delivery when the placenta detaches.

Can HDN occur in first pregnancy?

Since HDN usually occurs during pregnancy, and less commonly through a blood transfusion, this rarely causes fetal anemia in a first pregnancy. However, once it appears, it tends to become more severe with each subsequent affected pregnancy.