Fetal Hemolytic Disease (Rh & ABO Incompatibility)

Fetal hemolytic disease occurs when there is an incompatibility between the blood types of a mother and her baby. Generally, blood is typed as A, B, O or AB. In addition, blood is typed according to its Rh factor, which is either positive or negative. While incompatibility can arise in a number of situations, the one that is the most serious is when a Rh negative mother has a Rh positive baby. In such cases, a process known as alloimmunization may take place, which is when the mother's blood develops antibodies to her baby's blood. The antibodies will then attack the baby's blood and serious complications, up to and including death, may occur. Similarly, the same type of process can arise when incompatibility is caused by differences in the following blood types.

Mother's Blood Type OAB
Baby's Blood Type A or BBA

The complications that rise from ABO incompatibility are normally less than those associated with Rh incompatibility. In either case, diagnostic and treatment protocols have been developed that greatly decrease the risk of developing serious adverse consequences when blood type incompatibilities are present.

The American College of Obstetricians and Gynecologists (ACOG) publishes Practice Bulletins to aid its members in making decision about appropriate obstetric and gynecologic care. In May of 1999, ACOG published Practice Bulletin No. 4, Prevention of Rh D Alloimmunization. This bulletin noted that "before the introduction of anti-D immune globulin, hemolytic disease of the fetus and newborn affected 9-10% of pregnancies and was a major cause of perinatal morbidity and mortality." The bulletin further noted that the administration of the anti-D immune globulin is successful in reducing the rate of developing antibodies. ACOG instructs its members that protocols have been developed which are "responsible for the dramatic decrease in alloimmunization and subsequent hemolytic disease in the past two decades." Despite the development of these protocols, ACOG noted that " Rh D alloimmunization remains a clinical concern, with many cases due to failure to follow established protocols."

Since May of 1999, these protocols have continued to be refined. One well known author has noted that "modern approaches to fetal hemolytic disease have drastically reduced the impact of this disease on the family. Though we may be cognizant that it may occur, we do not expect to lose a fetus to hemolytic disease." Fetal Hemolytic Disease, Weiner CP, Chapter 14, High Risk Pregnancy Management Options, James DK, Steer PJ, Weiner CP, Gonik B. 3rd Ed. 2006, p. 307.

With respect to management options, protocols and recommendations have been developed in the following areas: (1) prevention of Rh hemolytic disease in nonimmunized women; (2) prediction of disease severity in immunized women; (3) available treatments; (4) delivery options; and (5) neonatal care. Despite such protocols, AGOG has recognized that these protocols are not always followed. More specifically, AGOG has recognized that:

Preventable Rh D alloimmunization occurs in susceptible Rh D-negative women for the following three reasons:

1. Failure to administer an antenatal dose of anti-D immune globulin at 28-29 weeks of gestation;

2. Failure to recognize clinical events that place patients at risk for alloimmunization and failure to administer anti-D immune globulin appropriately;

3. Failure to administer or failure to administer timely anti-D globulin postnatally to women who have given birth to an Rh D-positive or untyped fetus .

Prevention of Rh D Alloimmunization, ACOG Practice Bulletin, Clinical Management Guidelines for Obstetrician-Gynecologists, No. 4, May 1999.

The failure to follow one or more of these protocols may result in injury to the baby. If your baby is injured due to blood type incompatibility, you should consider having both your and your baby's medical records reviewed by an experienced medical malpractice law firm.


[1] In addition to the Rh negative/positive characterization, a second designation is added to identify the specific type of antigen, e.g. Rh D, C, E, c, e.