While early diagnosis is an important factor in successfully treating hemolytic disease of the fetus and newborn (HDFN), it can be prevented in some instances.
HDFN is a severe condition that can occur during pregnancy and after delivery, as a result of the mother’s and baby’s blood being incompatible.
Identifying women at risk
Whether or not a pregnant woman is more at risk of developing HDFN during pregnancy depends on her blood type. This is why a blood test at the first prenatal visit includes screening for blood factor and blood type.
Rh incompatibility
The Rh factor refers to an inherited protein that exists on the surface of red blood cells.
If you are Rh-positive, you have the protein. If you are Rh-negative, you do not have it. Your blood type will have a corresponding “+” or “–” to reflect this.
Only 15% of the population is Rh-negative. Thus, an Rh-negative woman who is pregnant or planning to get pregnant is likely to have a Rh-positive baby. If she is exposed to the blood of her Rh-positive baby, her current pregnancy and subsequent pregnancies could be at risk.
At your first prenatal appointment, your blood will be tested to determine your blood type. Additionally, if you are Rh-negative, an indirect Coombs test will ascertain if you have any antibodies to the Rh factor in your blood. This would mean you are already sensitized to the Rh-positive blood your baby may have, putting them at risk.
In either case, if you are Rh-negative, an injection of Rh immune globulin (also known as RhoGAM) is recommended at 28 weeks gestation to prevent sensitization to your baby’s potentially Rh-positive blood. Following delivery, if your baby is confirmed to be Rh-positive, another injection will be required within 72 hours of birth.
RhoGAM helps prevent the production of Rh antibodies, which in most cases will protect your baby and prevent HDFN from developing. The injection is considered to be safe and effective when protocols are followed; however, it may be less effective if your blood is already sensitized.
It is important that your doctor and family are aware if you are Rh-negative. It must be mentioned to your doctor if you experience vaginal bleeding, particularly if you haven’t yet had your RhoGAM injection.
Blood type incompatibility
Another cause of HDFN is ABO incompatibility, and these cases are not preventable. It is generally rarer and less serious, with less than 1% of newborns diagnosed with hemolytic disease as a result of ABO incompatibility. It applies mainly to women with blood type O, as they naturally express antibodies to A and B blood types. These antibodies are also likely to be immunoglobulin G (IgG) and can cross the placenta to attack the foreign blood of the fetus. While ABO incompatibility can be predicted and easily detected, there are no known preventative measures during pregnancy.
