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Anemia in the Newborn


Andrew W. Walter

, MS, MD, Sidney Kimmel Medical College at Thomas Jefferson University

Reviewed/Revised Nov 2022
Topic Resources

Anemia is a disorder in which there are too few red blood cells in the blood.

  • Anemia can occur when red blood cells are broken down too rapidly, too much blood is lost, or the bone marrow does not produce enough red blood cells.

  • If red blood cells are broken down too rapidly, anemia may develop and levels of bilirubin (a yellow pigment produced during the normal breakdown of red blood cells) increase, and the newborn’s skin and the whites of the eyes can appear yellow (a condition called jaundice).

  • If a large amount of blood is lost very rapidly, the newborn may become seriously ill and develop shock, appear pale, have a rapid heart rate, and have low blood pressure along with rapid, shallow breathing.

  • If there is less severe blood loss, or the blood is lost gradually, the newborn may appear normal but pale.

  • Treatment may involve fluids given by vein (intravenously) followed by a blood transfusion or an exchange transfusion.

Red blood cells contain hemoglobin, a protein that gives blood its red color and enables it to carry oxygen from the lungs and deliver it to all body tissues. Oxygen is used by cells to help produce from food the energy that the body needs, leaving carbon dioxide as a waste product. Red blood cells carry carbon dioxide away from the tissues and back to the lungs. When the number of red blood cells is too low, blood carries less oxygen, and fatigue and weakness develop (see also Overview of Anemia Overview of Anemia Anemia is a condition in which the number of red blood cells is low. Red blood cells contain hemoglobin, a protein that enables them to carry oxygen from the lungs and deliver it to all parts... read more in adults.)

Bone marrow contains specialized cells that produce blood cells. Normally, the bone marrow produces very few new red blood cells between birth and 3 or 4 weeks of age, causing a slow drop in the red blood cell count (called physiologic anemia) over the first 2 to 3 months of life.

More severe anemia can occur when

  • Red blood cells are broken down too rapidly (a process called hemolysis).

  • A lot of blood is taken from premature newborns for blood tests.

  • Too much blood is lost during labor or delivery.

  • The bone marrow does not produce enough new red blood cells.

More than one of these processes can occur at the same time.

Rapid breakdown of red blood cells (hemolysis)

The red blood cells may also be rapidly destroyed if the newborn has a hereditary abnormality of the red blood cells. An example is hereditary spherocytosis, in which the red blood cells look like small spheres when viewed under a microscope.

Another example occurs in infants who lack a red blood cell enzyme called glucose-6-phosphate dehydrogenase (G6PD deficiency Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an inherited genetic disorder that can result in destruction of red blood cells (hemolysis) after an acute illness or use of certain drugs... read more ). In these infants, exposure of the mother and fetus to certain drugs used during pregnancy (such as aniline dyes, sulfa drugs, and many others) may result in rapid breakdown of red blood cells.

Hemolysis may also occur with hemoglobinopathies. Hemoglobinopathies are genetic disorders that affect the structure or production of hemoglobin. Hemoglobin is a protein inside red blood cells that enables the cells to carry oxygen from the lungs and deliver it to all parts of the body. Thalassemia Thalassemias Thalassemias are a group of inherited disorders resulting from an imbalance in the production of one of the four chains of amino acids that make up hemoglobin (the oxygen-carrying protein found... read more is an example of a hemoglobinopathy that can rarely cause problems in newborns.

Blood loss

Blood loss is another cause of anemia. Blood loss in a newborn can occur in many ways. For example, blood is lost if there is a large movement of the fetus's blood across the placenta Development of the Fetus and Placenta A baby goes through several stages of development, beginning as a fertilized egg. The egg develops into a blastocyst, an embryo, then a fetus. During each normal menstrual cycle, one egg (ovum)... read more Development of the Fetus and Placenta (the organ that connects the fetus to the uterus and provides nourishment to the fetus) and into the mother's blood circulation (called fetal-maternal transfusion). Blood can also be lost if too much blood gets trapped in the placenta at delivery, which can happen when the newborn is held above the mother’s abdomen for too long before the umbilical cord is clamped.

Sometimes blood loss occurs when the newborn is injured during delivery. For example, rupture of the liver or spleen during delivery may cause internal bleeding. Rarely, bleeding can occur under the newborn's scalp when a vacuum extractor or forceps Operative Vaginal Delivery Operative vaginal delivery is delivery using a vacuum extractor or forceps. A vacuum extractor consists of a small cup made of a rubberlike material that is connected to a vacuum. It is inserted... read more is used during delivery.

Blood loss can also occur in newborns who have a deficiency of vitamin K Vitamin K Deficiency Vitamin K deficiency is most common in infants, especially those who are breastfed. The deficiency can cause bleeding; therefore, all newborns should be given a vitamin K injection. Bleeding... read more . Vitamin K is a substance that helps the body form blood clots and helps control bleeding. Vitamin K deficiency can cause hemorrhagic disease of the newborn, which is characterized by a tendency to bleed. Newborns normally have low levels of vitamin K at birth. To prevent bleeding, newborns are routinely given an injection of vitamin K at birth.

Internal bleeding that leads to anemia can occur in babies who are born with a severe, inherited bleeding disorder such as hemophilia Hemophilia Hemophilia is a hereditary bleeding disorder caused by a deficiency in one of two blood clotting factors: factor VIII or factor IX. Several different gene abnormalities can cause the disorder... read more , especially with a difficult delivery.

Frequently drawing a sick newborn's blood may also contribute to anemia.

Decreased red blood cell production

Before birth, the fetus's bone marrow may fail to produce enough new red blood cells. This rare defect may result in severe anemia. Examples of this lack of production include rare genetic disorders such as Fanconi syndrome Fanconi Syndrome Fanconi syndrome is a rare disorder of kidney tubule function that results in excess amounts of glucose, bicarbonate, phosphates (phosphorus salts), uric acid, potassium, and certain amino acids... read more and Diamond-Blackfan anemia.

After birth, some infections (such as cytomegalovirus infection Cytomegalovirus (CMV) Infection Cytomegalovirus infection is a common herpesvirus infection with a wide range of symptoms: from no symptoms to fever and fatigue (resembling infectious mononucleosis) to severe symptoms involving... read more , syphilis Syphilis Syphilis is a sexually transmitted infection caused by the bacteria Treponema pallidum. It can occur in three stages of symptoms, separated by periods of apparent good health. Syphilis... read more Syphilis , and human immunodeficiency virus Human Immunodeficiency Virus (HIV) Infection in Children and Adolescents Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and makes people more vulnerable to other infections and some cancers... read more [HIV]) may also prevent the bone marrow from producing enough red blood cells. Rarely, newborns may also be lacking certain nutrients, such as iron Iron Deficiency Iron deficiency is a common cause of anemia, a condition in which the number of red blood cells is low. Iron deficiency usually results from loss of blood in adults (including bleeding from... read more , folate Folate Deficiency Folate deficiency is common. Because the body stores only a small amount of folate, a diet lacking in folate leads to a deficiency within a few months. Not eating enough raw leafy vegetables... read more (folic acid), and vitamin E Vitamin E Deficiency Vitamin E deficiency caused by a diet low in vitamin E is common in countries with high rates of food insecurity. In countries with low rates of food insecurity, the cause is usually an absorption... read more , which may cause anemia because the bone marrow is then unable to produce red blood cells.

Symptoms of Anemia in the Newborn

Most infants with mild or moderate anemia have no symptoms. Moderate anemia may result in sluggishness (lethargy) or poor feeding.

Complications of anemia in newborns

Newborns who have suddenly lost a large amount of blood during labor or delivery may be in shock Shock Shock is a life-threatening condition in which blood flow to the organs is low, decreasing delivery of oxygen and thus causing organ damage and sometimes death. Blood pressure is usually low... read more and appear pale and have a rapid heart rate and low blood pressure, along with rapid, shallow breathing.

When the anemia is a result of rapid breakdown of red blood cells, there is also an increased production of bilirubin, and the newborn’s skin and whites of the eyes may appear yellow (jaundice Jaundice in the Newborn Jaundice is a yellow color to the skin and/or eyes caused by an increase in bilirubin in the bloodstream. Bilirubin is a yellow substance formed when hemoglobin (the part of red blood cells... read more Jaundice in the Newborn ).

Diagnosis of Anemia in the Newborn

  • Before birth, prenatal ultrasound

  • After birth, symptoms and blood tests

After birth, the diagnosis of anemia is based on symptoms and is confirmed with tests done on a sample of the newborn's blood. Additionally, in some states of the United States, newborns are screened for some of the causes of anemia, such as G6PD deficiency.

Treatment of Anemia in the Newborn

  • For anemia caused by rapid blood loss, fluids by vein and a blood transfusion

  • For anemia caused by hemolytic disease, treatment varies

  • Sometimes iron supplements

Most healthy premature infants have mild anemia and do not require any treatment.

Very severe anemia caused by hemolytic disease may also require a blood transfusion, but the anemia is more often treated with an exchange transfusion Exchange transfusion Jaundice is a yellow color to the skin and/or eyes caused by an increase in bilirubin in the bloodstream. Bilirubin is a yellow substance formed when hemoglobin (the part of red blood cells... read more Exchange transfusion , which both lowers the bilirubin level and increases the red blood cell count. In an exchange transfusion, a small amount of the newborn’s blood is gradually removed and replaced with equal volumes of fresh donor blood.

Some infants are given liquid iron supplements to help them increase their red blood cell count faster.

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