Fetal Anemia During Pregnancy

6 min read

Written by Pradeep

Pradeep

Fetal Anemia During Pregnancy

It is common knowledge that a pregnant woman can get anaemic during pregnancy and may require nutritional and dietary supplements to compensate for the low haemoglobin levels in the blood. But did you know that the fetus can get anaemic too? Surprisingly, fetal anaemia during pregnancy doesn’t have anything to do with the mother’s diet or lack of it. Instead, it can occur due to certain physiological conditions of the fetus or infections of the mother.

Fetal anaemia, although quite rare, can be a serious medical condition, sometimes even harming the life of the fetus. Lack of enough blood supply to the fetus means less oxygen, which means more pressure on the fetal heart, and has to then work harder and faster to ensure proper blood supply to all the parts of the fetal body. In rare and serious fetal anaemia, the body organs may start failing one by one due to insufficient oxygen supply. Read the article to know more about this serious but possible condition in fetuses during pregnancy.

In This Article

What is Fetal Anemia?

Fetal anemia is a condition characterized by an inadequate number or amount of red blood cells and hemoglobin in the circulatory system of the fetus. Just like us adults, fetuses too use red blood cells to carry oxygen and the lack of production of the same or destruction of the red blood cells at a speed that is more than their production could, could cause a fetus to have anemia or low blood counts.

What Are the Consequences of Fetal Anemia?

Just like an adult, the fetus also has a well-functioning circulatory system. Fetal anemia results in RBC (red Blood Cells) count to fall below the normal level. RBC carries oxygen to the cells and various organs of the developing fetus. Inadequate RBC means inadequate oxygen supply.

Just like other issues that affect the fetus, fetal anemia also varies from mild to severe. If the intensity of the anemia is high (though it very rarely happens), the fetal heart tries to deal with the insufficient quantity or quality of red blood cells by pumping harder. Thus, severe anemia can put the fetus at the risk of heart failure. The fetal anemia can also result in the abnormal amount of fluid build up in two or more body parts of the fetus. This is called hydrops. Severe swelling interferes with the organ functions of the fetus. Untreated fetal anemia can lead to fetal death.

Causes of Fetal Anemia During Pregnancy

Causes of Fetal Anemia

This condition happens, either, because of no sufficient RBC is produced by the fetus, or, because of the RBC is produced by the fetus is being destroyed faster than they are produced.

There are many issues, which lead to fetal anemia.

1. Maternal RBC Alloimmunization

Alloimmunization happens when the mother’s and fetus’s RBC are incompatible. The unborn baby might have received some blood antigens from the father that are not present in the mother. Therefore, the maternal antibodies that cross the placenta will not able to recognize the fetal red blood cell antigens. Thus, the mother’s system develops antibodies to attack the RBC of the fetus, resulting in its destruction and developing fetal anemia.

2. Rh(D) Alloimmunization

Rh (D) incompatibility between the mother and baby (Rh-positive baby is conceived by the Rh-negative mother) was a common cause of fetal anemia. However, nowadays, it is very rarely happens, as the awareness and administration of Rh D immune globulin shots are increased.

[Read : RhoGam Shot During Pregnancy]

3. Parvo Virus Infection

Parvo virus infection generally is not a serious infection. This infection most commonly affects preschool and school-age children. Adults can also be infected by the fifth disease (common name of parvovirus infection), too. A virus called parvovirus B19, which hinders with the production of red blood cells, causes it.

If a pregnant woman catches this infection, the virus attacks the RBC of the fetus that developing in its bone marrow. If not closely monitored, the outcome can be an intense fetal anemia and even fetal death, especially if the infection happens prior to the 20th week of pregnancy.

4. Tumors

Sacrococcygeal Teratoma (SCT) is a rare tumor that develops at the tailbone of the fetus. A fetus with SCT develops very large blood vessels. As a result, the fetal heart must do extra work while trying to pump more blood through the tumor.

The RBC that formed in the bone marrow also will be insufficient to fill the blood vessels. As a result (with the same resources) the fetal body tends to produce more RBC. This affects the quality of the RBC. This can lead to fetal anemia.

5. Genetic or Metabolic Disorder of the Fetus

Fetal anemia is observed, when the fetus is undergoing genetic or metabolic disorder like Down’s syndrome, Gaucher disease, G-6-PD deficiency, etc.

6. Placenta Sharing

If the placenta is shared like in a twin pregnancy, because of the decreased blood flow, fetal anemia can happen to (mostly) one of the babies.

Can a Fetus at Risk of Fetal Anemia be Identified?

RH Antibody titre

It is possible to identify a fetus that possesses a risk of developing fetal anemia. Screening for iso-immunization is a part of the routine prenatal lab tests. If the result is positive, tests are conducted to identify the antibody and to determine the antibody level (titer). The test can be repeated in every 3 to 4 weeks. Not all the maternal antibody gives rise to fetal anemia. With a help of a reference table, the risk of the antibody identified can be evaluated.

If it possesses risk, to determine if the fetal RBC is able to produce the antigen, the father’s blood is examined. If the result is negative, theoretically, the fetus is safe. Of not, the fetus poses the risk of fetal anemia.

If the expecting mother is exposed to parvo virus, and if this is her first-time exposure, she should be closely monitored for the signs of fetal anemia.

How is Fetal Anemia Diagnosed?

Fetal anemia can be diagnosed:

1. By Performing an Ultrasound

ultrasound scan for fetal anemia

Fetal anemia can be diagnosed when conducting a prenatal ultrasound. If the ultrasound shows swelling in the fetal tissue, it can be due to the fluid accumulation. If one of the fetal arteries in the brain called middle cerebral artery (MCA) shows increased blood flow in an ultrasound (Doppler evaluation), fetal anemia can be suspected. This is because one of the fetal response to the anemia is the increased blood flow to the brain.

[Read : Doppler Scan During Pregnancy]

2. By Conducting Maternal Blood Test

Conducting a maternal blood test can confirm the presence of certain antibodies, which can cause fetal anemia.

3. By Invasive Procedures

amniocentesis

Though difficult and not very safe to perform as it carries an increased risk of miscarriage and preterm delivery, if the circumstances demand, the invasive procedures like amniocentesis and fetal blood sampling is performed, by which, the fetal anemia can be diagnosed with 100% accuracy.

What Are the Treatment Choices For Fetal Anemia?

The treatment choice depends on the cause and severity of the anemia. In the case of mild anemia, the baby will be closely monitored and delivered earlier (if possible).

Fetal transfusion is performed in the case of moderate to severe anemia. The RBC transfusion (Rh –ive blood, which is confirmed carry no infection) through the umbilical vein, which is assisted by an ultrasound is performed. The outcome of this treatment is excellent, though the transfusion is not performed after 34 weeks. There is a good chance of a vaginal delivery, if the baby tolerates the labor.

However, owing to the complication and the rarity of the condition, it is imperative that treatment be sought at a facility that handles such type of cases and carries a good record. The treatment must be performed under the supervision of an expert.

Read Also: What Is Fetal Echocardiography – Purpose, Procedure and Risks

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