What are the implications of O- (O negative) blood type on prenatal care?

From the Guidelines

Pregnant women with O negative blood type should receive RhoGAM (Rh immunoglobulin) injections at 28 weeks of pregnancy and again within 72 hours after delivery if their baby has a positive blood type to prevent Rh incompatibility complications. This is based on the recommendation that if a mother has not had prenatal blood grouping or is Rh-negative, a direct antibody test (or Coombs’ test), blood type, and an Rh (D) type on the infant’s (cord) blood are strongly recommended 1.

Key aspects of prenatal care for women with O negative blood type include:

• Receiving RhoGAM injections to prevent the development of antibodies against an Rh-positive baby's blood
• Monitoring for anemia, which is slightly more common in O negative individuals
• Blood typing early in pregnancy to determine the need for RhoGAM injections
• Standard prenatal care, including folic acid supplementation, proper nutrition, and regular checkups

It's also important to note that O negative mothers can safely donate blood to babies of any blood type, but can only receive O negative blood themselves. Regular prenatal visits are essential to monitor for any potential complications and to ensure the best possible outcome for both the mother and the baby. According to 1, if the maternal blood is group O, Rh-positive, it is an option to test the cord blood for the infant’s blood type and direct antibody test, but it is not required provided that there is appropriate surveillance, risk assessment before discharge, and follow-up. However, this does not directly apply to O negative blood type, and the primary concern remains preventing Rh incompatibility complications.

From the FDA Drug Label

HyperRHO S/D Full Dose is recommended for the prevention of Rh hemolytic disease of the newborn by its administration to the Rho(D) negative mother within 72 hours after birth of an Rho(D) positive infant,(12) providing the following criteria are met: The mother must be Rho(D) negative and must not already be sensitized to the Rho(D) factor. HyperRHO S/D Full Dose should be administered within 72 hours to all nonimmunized Rho(D) negative women who have undergone spontaneous or induced abortion, following ruptured tubal pregnancy, amniocentesis or abdominal trauma unless the blood group of the fetus or the father is known to be Rho(D) negative.

For a pregnant woman with O- blood, which is Rho(D) negative, the key points for prenatal care are:

• Rh immune globulin (IM) should be administered to prevent Rh hemolytic disease of the newborn if the father is Rho(D) positive or if the fetal blood group is unknown.
• Administration of HyperRHO S/D Full Dose is recommended within 72 hours after birth of an Rho(D) positive infant or after any event that may cause fetomaternal hemorrhage, such as abortion, amniocentesis, or abdominal trauma 2.
• If the father can be determined to be Rho(D) negative, HyperRHO S/D Full Dose need not be given 2.
• Administration of Rh immune globulin (IM) at 28 weeks’ gestation and another dose after delivery may further reduce the incidence of isoimmunization 2.

From the Research

Prenatal Care and O- Blood Type

• Prenatal care for individuals with O- blood type involves considering the potential risks of hemolytic disease of the newborn (HDN) due to the presence of anti-A and anti-B antibodies in the mother's blood 3.
• The strength of the A antigen on the red blood cells of newborns can vary, which can affect the risk of HDN 3.
• Studies have shown that the transfusion of blood or blood components containing ABO-incompatible plasma can pose a risk of hemolytic reactions, particularly if the titer of anti-A or anti-B antibodies is high 4.
• The use of low-titer group O whole blood as a universal blood type can minimize the risk of hemolytic reactions in emergency situations 4.

Anti-A and Anti-B Antibodies

• Anti-A and anti-B antibodies are naturally occurring antibodies found in the plasma of individuals with non-AB blood types, including those with O- blood type 5.
• These antibodies can be present in intravenous immunoglobulin (IVIG) products, which can pose a risk of transfusion reactions in individuals with A, B, or AB blood types 5.
• The titers of anti-A and anti-B antibodies can vary, and high titers can increase the risk of hemolytic reactions 4, 5.

COVID-19 Susceptibility and O- Blood Type

• Studies have suggested that individuals with O- blood type may have a lower susceptibility to COVID-19 due to the presence of natural anti-A and anti-B antibodies, which can interfere with the SARS-CoV-2 virus 6.
• The titers of these antibodies, particularly the IgG isotype, may be an important determinant of susceptibility and severity of COVID-19 6.