Fetal Anemia

An uncommon but serious condition, fetal anemia is characterized by low levels of hemoglobin and circulating red blood cells in a fetus. Hemoglobin and red blood cells play a vital role in healthy blood function and delivering oxygen throughout the body. The baby’s heart may try to compensate for the lack of healthy red blood cells by pumping blood faster, which can lead to serious medical complications.

Fetal Anemia Causes

The most common cause of fetal anemia is isoimmunization, or an incompatibility between the red blood cells of the baby and mother (this is also referred to as alloimmunization). Rh incompatibility is often to blame—for example, when the mother has Rh-negative blood while the baby has Rh-positive blood. The mother’s immune system may recognize the baby’s “foreign” blood type as a threat and respond by launching antibodies to attack healthy fetal red blood cells.

Less commonly, fetal anemia is caused by:

• Maternal infections, such as fifth disease and syphilis
• Twin anemia polycythemia sequence (TAPS)
• Down syndrome and other genetic disorders
• Vascular tumors affecting the baby or placenta
• Issues with the baby’s red blood cell production

Fetal Anemia Symptoms

Fetal anemia does not usually cause noticeable symptoms for the mother. For the baby, life-threatening complications may occur if anemia is left untreated, such as heart failure and hydrops, a condition marked by irregular fluid buildup in the baby’s body.

Fetal Anemia Diagnosis

There are multiple approaches that can be used to diagnose fetal anemia:

• Prenatal ultrasound to identify signs of hydrops and heart failure or measure blood flow in the baby’s brain
• Amniocentesis to withdraw fluid from the baby’s amniotic sac
• Testing the mother’s blood for certain antibodies that may indicate fetal anemia
• Testing the baby’s blood by inserting a small needle into the uterus 

Fetal Anemia Treatments

The prognosis for fetal anemia is often excellent when it is promptly identified and treated. At Tampa General Hospital’s Women’s Institute, our multidisciplinary team delivers highly specialized care to mothers and babies with fetal anemia and other complex prenatal conditions. Some common care approaches for fetal anemia include careful monitoring of the baby’s blood flow and ultrasound-guided fetal blood transfusion, which is performed through the umbilical cord.