Rh incompatibility

Rh incompatibility is a condition that can occur during pregnancy. It happens when a pregnant person has Rh-negative blood and their baby has Rh-positive blood. The Rh factor is a protein found on the surface of red blood cells. About 85% of people have this protein and are considered Rh-positive. The remaining 15% lack the protein and are Rh-negative.

When an Rh-negative mother carries an Rh-positive baby, their blood types don't match. If the baby's blood enters the mother's bloodstream, her immune system may see the Rh-positive cells as foreign invaders. Her body then creates antibodies to attack these cells. This process is called sensitization and usually happens during delivery, miscarriage, or certain medical procedures.

The first pregnancy with an Rh-positive baby rarely causes problems because sensitization takes time. However, once a mother develops these antibodies, they remain in her blood. In future pregnancies with Rh-positive babies, these antibodies can cross the placenta and attack the baby's red blood cells. This can lead to hemolytic disease of the newborn, a serious condition that causes anemia and jaundice in babies.

Most Rh-negative mothers experience no symptoms during pregnancy, even when carrying an Rh-positive baby. Rh incompatibility itself doesn't make the mother feel sick or different. The condition affects the baby, not the pregnant person directly.

Babies affected by Rh incompatibility may show these signs after birth:

• Yellow skin and eyes, a condition called jaundice
• Pale skin due to anemia or low red blood cell count
• Enlarged liver or spleen that a doctor can feel during examination
• Swelling or fluid buildup in the body, called hydrops fetalis in severe cases
• Low muscle tone or appearing listless and weak
• Rapid heart rate as the body tries to compensate for low oxygen

In severe cases that are not treated, babies may develop serious complications. Early detection through blood testing allows doctors to monitor and treat the condition before birth.

Rh incompatibility is caused by a mismatch between the mother's and baby's Rh blood types. It occurs when an Rh-negative mother becomes pregnant with an Rh-positive baby. The baby inherits the Rh-positive factor from their biological father. If the father is Rh-positive, there's a chance the baby will be too. When the baby's Rh-positive blood cells enter the mother's bloodstream, her immune system recognizes them as foreign and produces antibodies against them.

Several events during pregnancy can cause the baby's blood to mix with the mother's blood. These include delivery, miscarriage, abortion, ectopic pregnancy, amniocentesis, chorionic villus sampling, trauma to the abdomen, and bleeding during pregnancy. The risk increases with each subsequent pregnancy if the mother has been sensitized. Without preventive treatment, the antibodies created in one pregnancy can harm future Rh-positive babies. Women who have never been pregnant can also be sensitized through blood transfusions with Rh-positive blood, though this is rare with modern blood typing practices.

Rh incompatibility is diagnosed through blood tests done early in pregnancy. Every pregnant person receives blood typing tests at their first prenatal visit. These tests determine both the ABO blood type and the Rh factor. If the mother tests Rh-negative, doctors will also test the biological father's blood type when possible. This helps determine the likelihood that the baby will be Rh-positive.

Doctors also perform an antibody screen, called an indirect Coombs test, to check if the mother has already developed Rh antibodies from a previous pregnancy or transfusion. If antibodies are detected, additional monitoring is needed throughout pregnancy. The test is typically repeated at 28 weeks of pregnancy for Rh-negative mothers who haven't been sensitized. After delivery, the baby's blood type is tested immediately. If the baby is Rh-positive, a direct Coombs test checks for antibodies attached to the baby's red blood cells. Talk to your doctor about specialized prenatal testing and monitoring for this condition.

Treatment for Rh incompatibility focuses on prevention and early intervention. The main approaches include:

• Rh immunoglobulin injections, called RhoGAM, given to Rh-negative mothers at 28 weeks of pregnancy and within 72 hours after delivery if the baby is Rh-positive
• RhoGAM injections after any event that could cause blood mixing, such as miscarriage, amniocentesis, or abdominal trauma
• Close monitoring with ultrasounds and blood tests throughout pregnancy if sensitization has already occurred
• Intrauterine blood transfusions for severely affected babies while still in the womb
• Early delivery if the baby shows signs of distress or severe anemia
• Phototherapy, or light treatment, for newborns with jaundice to break down excess bilirubin
• Blood transfusions for newborns with severe anemia or high bilirubin levels
• Intravenous immunoglobulin for babies to reduce the breakdown of red blood cells

With proper preventive care, most cases of Rh incompatibility can be avoided entirely. RhoGAM is highly effective at preventing sensitization when given at the right times. Mothers who receive this treatment can safely have multiple pregnancies without complications.