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Fetal Anemia During Pregnancy

5 min read

During pregnancy, you are not the only one who can be anemic. Your little one also has a chance of being anemic. This is called fetal anemia. It is not as simple as it sounds. Go on reading to know more about fetal anemia, its cause, and treatment.
Fetal anemia

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 swell ing interferes with the organ functions of the fetus. Untreated fetal anemia can lead to fetal death.

What Causes 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.

  • 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
  • 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
  • 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
  • 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
  • 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.
  • Pl acenta 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?

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:

  • By performing an ultrasound: 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
  • By conducting maternal blood test: Conducting a maternal blood test can confirm the presence of certain antibodies, which can cause fetal anemia
  • By invasive procedures: 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.

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