Fetal Anemia


What is Fetal Anemia?

Fetal anemia is a rare, serious condition in which a fetus doesn’t have enough healthy red blood cells.

When the amount of red blood cells falls below normal levels, it can adversely affect the fetus and the pregnancy. The condition can range from mild to severe.

How does fetal anemia affect my baby?

Red blood cells deliver oxygen to the body and developing organs. In severe cases of fetal anemia, where the body isn’t receiving enough oxygen, the fetal heart has to work harder, pumping faster to try and increase oxygen delivery to the body.

The result can be heart failure, causing an abnormal buildup of fluid throughout the baby’s body, known as hydrops fetalis. Untreated, the condition can be life-threatening.


One of the most common causes of fetal anemia is red blood cell alloimmunization, or incompatibility between the mother’s red blood cells and the fetal red blood cells.

When the baby’s blood crosses into the mother’s bloodstream through the placenta, the mother’s immune system reacts as if it is a foreign substance, producing “antibodies” that attack and destroy the fetal red blood cells. Red cell alloimmunization can cause severe fetal anemia if not monitored and treated. It is typically caused by a previous blood transfusion or blood cells from a prior pregnancy. Once a pregnancy is affected by this condition, there is a high likelihood of future pregnancies being affected even more severely, requiring close monitoring of mother and baby.

Additional causes of fetal anemia include:

  • Maternal infections, including parvovirus (“fifth disease”), toxoplasmosis, cytomegalovirus (CMV), coxsackie virus, and syphilis
  • Vascular tumors of the fetus or placenta
  • Problems with the baby’s production of red blood cells
  • Twin anemia polycythemia sequence (TAPS), a complication of pregnancies with identical twins who share a placenta (monochorionic twins), where there is an imbalance in red blood cells
  • Genetic disorders, including Down syndrome
  • Following laser therapy for twin-twin transfusion syndrome (TTTS)
  • Fetal blood loss from fetal interventions
  • Fetomaternal hemorrhage from maternal abdominal trauma resulting in placental abruption.


Diagnostic testing for fetal anemia may include:

  • Ultrasound – to detect signs of fetal heart failure and hydrops caused by anemia. Ultrasound is also used to measure the speed of blood flow in the middle cerebral artery (MCA) of the fetal brain, another possible indicator. In a fetus with anemia, the blow flows to the brain at a faster rate.
  • Amniocentesis – to help determine the cause of the anemia, an ultrasound-guided procedure that uses a thin needle to withdraw a small amount of fluid from the amniotic sac for analysis
  • Maternal blood sample – to detect antibodies that can cause fetal anemia. If routine testing shows the mother has antibodies, more specialized testing can be done for the father and the fetus, and more frequent ultrasound testing may be recommended to monitor the fetus for anemia.
  • Fetal blood sampling - a procedure similar to an amniocentesis that involves placement of a small needle into the uterus to obtain a fetal blood sample from the umbilical cord. Talk with your physician about the risks involved, including early delivery and the loss of the pregnancy.

All testing should be performed by specialists highly trained and experienced in these procedures, and in the diagnosis and treatment of fetal anemia.

Specialized Evaluation and Care

If fetal anemia is suspected or diagnosed during pregnancy, you may be referred to a fetal center for further assessment and specialized care.

At Texas Children’s Fetal Center, we arrange for you to visit as quickly as possible for a comprehensive evaluation by a team of specialists experienced in diagnosing and treating this rare condition, including maternal-fetal medicine (MFM) physicians, fetal imaging experts, fetal surgeons, fetal cardiologists, genetic counselors and neonatologists.  

Following a thorough assessment, our specialists will meet with you about your results, answer any questions you have, and discuss treatment planning based on your baby’s condition.  

Treatment During Pregnancy

You and your baby will be closely monitored throughout pregnancy with regular ultrasounds to assess fetal health. Treatment during pregnancy depends on the severity of your baby’s condition and gestational age.

If the fetus shows evidence of anemia, a blood transfusion may be recommended to replace the fetal blood supply. During this ultrasound-guided procedure, red blood cells from a donor are injected into the fetus through a needle inserted through the mother’s abdomen and into the umbilical cord and/or fetal abdomen.

The goal of the procedure, also known as an intrauterine transfusion, is to replace healthy red blood cells into the fetal circulation and enable the pregnancy to continue as long as possible. If subsequent testing shows that the fetus is anemic, the procedure may need to be repeated. After delivery of the baby, another blood transfusion is usually necessary.


We recommend delivery at a hospital with the expertise and resources required to care for pregnancies involving fetal anemia, including the highest level neonatal intensive care unit (NICU)

Delivery and postnatal care should be carefully planned and coordinated with a team of maternal-fetal medicine specialists, neonatologists, and pediatric specialists experienced in working together to treat babies with this rare condition.

Our Fetal Center team works closely with pediatric experts from Texas Children’s Hospital, consistently ranked one of the best children’s hospitals in the nation by U.S. News & World Report. For our patients, that means seamless access to the critical care services and specialists your baby may need after birth, with no transfers required during the critical postnatal period. It also means that the pediatric experts responsible for treating your child at delivery have been part of their care team prior to birth.

Postnatal Care Team

Treatment needs for newborns with fetal anemia may include blood transfusions or treatment for jaundice, which may be severe. Babies with jaundice have high levels of bilirubin in their bloodstream, a byproduct from breakdown of red blood cells.

In addition, your baby will need to be monitored closely for the first few months for anemia.

Your baby’s postnatal care team may include:

Why Texas Children’s Fetal Center?

  • A single location for expert maternal, fetal and pediatric care. At Texas Children’s Hospital, you and your baby receive the specialized care required for the diagnosis and treatment of fetal anemia all in one location, for highly coordinated care and treatment planning, including immediate access to our level IV NICU.
  • A skilled, experienced team with proven outcomes. We have a dedicated team of maternal-fetal medicine specialists, fetal imaging experts, fetal surgeons, genetic counselors, neonatologists, and others who work in concert to care for you and your baby every step of the way, using proven protocols we’ve developed over the years. With their combined expertise and unified approach, this team offers the best possible care for babies with fetal anemia.
  • We care for your child’s needs at every stage of life. Our comprehensive approach starts with your first prenatal visit and continues through delivery, for the care and treatment of rare fetal conditions.

Patient Stories

Fetal Anemia Patient Story

From Fetal Anemia to Healthy Blood Cells

I’ll never forget that sinking stomach feeling when Dr. Karsan came into the exam room and said there were concerns.

Learn More

For more information or to schedule an appointment,

call Texas Children’s Fetal Center at 832-822-2229 or 1-877-FetalRx (338-2579) toll-free.

Our phones are answered 24/7. Immediate appointments are often available.