It is sometimes distressing for a new parent to be informed that the baby will require prolonged stay in the nursery due to “problems of incompatibility.”  The pediatrician may say that the baby had exhibited symptoms such as early jaundice or yellowing of the skin, due to the destruction of the baby’s red blood cells

Human red blood cells have markers called antigens that determine blood type.

Antibodies can develop in human bodies when exposed to a foreign antigen.  People who are Type A will develop antibodies when exposed to blood Type B and vice versa.

Those who are Type O will develop antibodies to both Type A and B should they receive wrong transfusion of these types of blood.

Before or during birth, some of the baby’s red blood cells leak into the mother’s circulation.  If the baby has a blood type different from that of the mother, the mother reacts by developing antibodies to it.

For instance, a blood type B baby might elicit an antibody reaction from a blood type O or blood type A mother.  The fetal red blood cells are attacked and destroyed.  This may cause fetal anemia, or sometimes, stillbirth.  After birth, this may cause jaundice and anemia in the infant within the first 24 hours.

While this condition, also referred to as blood type ABO incompatibility, may be present in some 20% of babies, only about 5% are clinically affected.  Babies and mothers with ABO incompatibility invariably exhibit only mild disease.  Firstborns are more commonly affected.  The condition rarely becomes more severe in subsequent pregnancies.

The D antigen, or the Rhesus antigen, is another type of blood antigen.  An individual is D positive if he has the antigen, and D negative if the antigen is absent.  When blood types are determined, each person is labeled Blood Type A, B, AB or O.  Appended to this is a plus (+) or a minus (-) sign.  A plus sign means the Rhesus antigen is present, and absent when it is a negative sign instead.

Almost 99% of Asians, including Filipinos, are D(+).  Only about 87% of Caucasians are D(+).  Mixed race couples may carry a fetus with a different Rhesus antigen from his mother.  During pregnancy or birth, there is a 17% risk of developing antibodies to the baby inside the womb.  This may result in fetal anemia, abnormal fetal heart rate patterns, and sometimes, fetal death.

After the baby is born, blood group incompatibility is suspected if the baby is yellow or jaundiced during the first 24 hours of life.  This is treated by phototherapy or exposure to artificial or sun light.  A pale baby can mean it is anemic.  Pediatricians recommend an immediate exchange transfusion to replace the destroyed red blood cells and to clear the baby’s circulation of maternal antibodies.

In the womb, such incompatibilities may only be detected if the fetus exhibits abnormal heart patterns.  Some fetuses may appear bloated – a condition scientifically known as “hydrops fetalis.”  Some may have enlarged livers and spleens as seen in ultrasound.  Should this be observed, the doctor may take a blood sample from the fetus.  If blood type incompatibility is established, the baby may be given blood transfusions to replace the destroyed red blood cells.

The best strategy is to prevent the occurrence of incompatibilities.  Awareness and early intervention can easily prevent potentially tragic consequences.

Each person should be aware of his blood type, especially the presence of the Rhesus antigens.  Mothers who are type O may develop antibodies if carrying a blood type A, B, or AB fetus.  This may occur if he partner has the A, B, or AB blood type.  Luckily, the clinical condition is mild, and treating the baby with exchange transfusions has produced good results.

The more fearsome condition is the Rhesus antigen incompatibility.  Unfortunately, this condition progresses with subsequent pregnancies.  The firstborn may survive, but the second baby may be attacked by a larger amount of antibodies developed during the first pregnancy.

Should the father’s blood type be Rhesus positive, doctors may recommend immune globulins (anti-D immunoglobulin or Rhogam TM) for a mother with Rhesus negative blood type.  It is best given at the 28th week of pregnancy, and again immediately after delivery.  It is also used to treat mothers who have had miscarriage or received a transfusion of Rhesus positive blood.