Glossary

When a person’s immune system develops antibodiesAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. against foreign antigensAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. from the same species—such as when an Rh-negativeRh-Negative A blood type trait that means your red blood cells lack the Rh(D) antigen. mother’s body forms antibodies against her baby’s Rh-positiveRh-Positive A blood type trait that means your red blood cells have the Rh(D) antigen. red blood cells.

A condition that occurs when the body doesn’t have enough healthy red blood cells to carry oxygen to its tissues. In HDFN, anemiaAnemia A condition that occurs when the body doesn’t have enough healthy red blood cells to carry oxygen to its tissues. In HDFN, anemia occurs when maternal antibodies destroy fetal red blood cells. occurs when maternal antibodiesAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. destroy fetal red blood cells.

A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigensAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens..

A blood test performed during pregnancy to look for antibodiesAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. that could affect a developing fetus.

A yellow substance produced when red blood cells break down. High bilirubinBilirubin A yellow substance produced when red blood cells break down. High bilirubin levels in newborns with HDFN can cause jaundice or, in severe cases, brain damage. levels in newborns with HDFN can cause jaundiceJaundice A common symptom of HDFN, jaundice is caused by excess bilirubin and is characterized by a yellow tint to the skin or eyes. or, in severe cases, brain damage.

A classification of blood based on inherited markers found on red blood cells. The ABO and RhRh factor A protein or antigen found on red blood cells. When an Rh-negative mother carries an Rh-positive fetus, her immune system may make antibodies that attack the fetus' red blood cells. blood groups are most common in HDFN.

A blood test used to detect antibodiesAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. attached to red blood cells. It helps confirm HDFN in newborns.

A non-invasive scan that measures blood flow speed in the fetus’ brain to diagnose anemiaAnemia A condition that occurs when the body doesn’t have enough healthy red blood cells to carry oxygen to its tissues. In HDFN, anemia occurs when maternal antibodies destroy fetal red blood cells.. Specifically, it checks the middle cerebral artery peak systolic velocity (MCA-PSVDoppler ultrasound A non-invasive scan that measures blood flow speed in the fetus' brain to diagnose anemia. Specifically, it checks the middle cerebral artery peak systolic velocity (MCA-PSV).).

An older term for HDFN, describing the severe destruction of fetal red blood cells caused by maternal antibodiesAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens..

A serious, sometimes fatal condition in which fluid builds up in a baby’s tissues and organs due to severe anemiaAnemia A condition that occurs when the body doesn’t have enough healthy red blood cells to carry oxygen to its tissues. In HDFN, anemia occurs when maternal antibodies destroy fetal red blood cells. from HDFN.

A common cause of jaundiceJaundice A common symptom of HDFN, jaundice is caused by excess bilirubin and is characterized by a yellow tint to the skin or eyes., this refers to higher than normal bilirubinBilirubin A yellow substance produced when red blood cells break down. High bilirubin levels in newborns with HDFN can cause jaundice or, in severe cases, brain damage. levels in the blood.

A procedure that delivers donor red blood cells to the fetus through the umbilical vein to treat severe anemiaAnemia A condition that occurs when the body doesn’t have enough healthy red blood cells to carry oxygen to its tissues. In HDFN, anemia occurs when maternal antibodies destroy fetal red blood cells. caused by HDFN.

A therapy made from donated antibodiesAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. that may help reduce the mother’s immune response and protect the fetus.

A common symptom of HDFN, jaundiceJaundice A common symptom of HDFN, jaundice is caused by excess bilirubin and is characterized by a yellow tint to the skin or eyes. is caused by excess bilirubinBilirubin A yellow substance produced when red blood cells break down. High bilirubin levels in newborns with HDFN can cause jaundice or, in severe cases, brain damage. and is characterized by a yellow tint to the skin or eyes.

A rare but serious brain condition caused by very high bilirubinBilirubin A yellow substance produced when red blood cells break down. High bilirubin levels in newborns with HDFN can cause jaundice or, in severe cases, brain damage. levels.

An obstetrician who specializes in managing high-risk pregnancies.

A treatment that uses special blue light to help newborns break down bilirubinBilirubin A yellow substance produced when red blood cells break down. High bilirubin levels in newborns with HDFN can cause jaundice or, in severe cases, brain damage. and prevent kernicterusKernicterus A rare but serious brain condition caused by very high bilirubin levels..

A protein or antigen found on red blood cells. When an Rh-negativeRh-Negative A blood type trait that means your red blood cells lack the Rh(D) antigen. mother carries an Rh-positiveRh-Positive A blood type trait that means your red blood cells have the Rh(D) antigen. fetus, her immune system may make antibodiesAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. that attack the fetus’ red blood cells.

A blood type trait that means your red blood cells lack the RhRh factor A protein or antigen found on red blood cells. When an Rh-negative mother carries an Rh-positive fetus, her immune system may make antibodies that attack the fetus' red blood cells.(D) antigen.

A blood type trait that means your red blood cells have the RhRh factor A protein or antigen found on red blood cells. When an Rh-negative mother carries an Rh-positive fetus, her immune system may make antibodies that attack the fetus' red blood cells.(D) antigen.

A preventive treatment that helps prevent Rh-negativeRh-Negative A blood type trait that means your red blood cells lack the Rh(D) antigen. mothers from developing antibodiesAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. that may harm the fetus.

The process by which a mother’s immune system becomes “primed” to recognize and attack fetal red blood cells carrying incompatible antigensAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens..

An imaging test that uses sound waves to monitor fetal growth, development and signs of complications during pregnancy.