The Rh factor is a protein on red blood cells that is part of one’s blood type. It is either positive or negative, and both are normal. Women who are Rh-positive are not at risk of Rh disease. However, when an Rh-negative mother is exposed to blood that is Rh-positive, most often through pregnancy with an Rh-positive child, her immune system mistakes this as an invader. This can lead to the child’s blood cells being destroyed.

Because it takes time for the immune system to respond to the Rh-positive blood cells, a mother’s first pregnancy with an Rh-positive child is unlikely to be affected. However, subsequent pregnancies are at increased risk.

Additionally, anything that exposes a mother to Rh-positive blood increases the risk of Rh disease. This includes:

• Miscarriage
• Ectopic pregnancy
• Abortion
• Trauma to the abdomen
• Procedures such as amniocentesis
• Blood transfusion
• Needle sticks
• Bone marrow transplantation

In newborns, these vary depending on the severity of the Rh disease and include:

• Yellowing of the child’s skin and/or eyes (i.e., jaundice)
• Decreased muscle strength
• Rapid pulse and breathing
• Enlarged organs (heart, spleen, liver)
• Brain damage
• Death

Your health care provider may order blood tests and other diagnostic tests to diagnose Rh disease. These include:

• Blood typing: This blood test determines if you are Rh-positive or Rh-negative.
• Antibody testing: This blood test determines if your immune system is already sensitized and is likely to attack the child’s blood cells.
• Genetic testing: This blood test during pregnancy determines the fetus’s blood type.
• Ultrasound: This imaging test can see if the fetus is affected by Rh disease.
• Amniocentesis: This test of the fluid surrounding the fetus can see if the fetus is affected by Rh disease.

If a mother is known to be at risk for Rh disease, a health care provider can use a prescription medication called anti-D (Rh) immunoglobulin. This injection is typically given twice during the pregnancy to prevent the mother’s immune system from attacking the child’s blood cells. One injection is typically at the 28-week mark of pregnancy and the other is shortly after the child’s birth. It may be given earlier in pregnancy or more than twice if there are any extra risk factors. This medication is very well tolerated.

However, this medication only works if the mother has not yet become sensitized to the Rh factor.

Treatment for Rh disease focuses on protecting the child from harm both during pregnancy and after birth. Treatment can include the following:

• Blood transfusion: The baby may need additional blood after birth.
• Supplements: The baby may need supplements, such as iron, to increase the amount of blood cells they make.
• Induction of pregnancy: If the Rh disease is severe, the health care provider may need to deliver the baby early.
• Phototherapy: Placing the newborn under special lights after birth can help rid the baby of dangerous toxins from the damaged blood cells.