All obstetrician-gynecologists know that pregnant patients who are Rh negative and exposed to a sufficient quantity of fetal red blood cells expressing Rh D antigen may become sensitized, producing Rh D antibodies that adversely impact future pregnancies with an Rh D-positive fetus, potentially causing hemolytic disease of the fetus and newborn. In countries where Rh D immune globulin is available, there is a consensus recommendation to administer Rh D immune globulin to Rh-negative pregnant patients at approximately 28 weeks’ gestation and at birth in order to decrease the risk of alloimmunization and hemolytic disease of the fetus and newborn in future pregnancies.1 In contrast to this global consensus, there is no worldwide agreement about how to manage Rh testing and Rh D immune globulin administration in cases of early pregnancy loss or abortion care before 12 weeks’ gestation. This editorial examines the evolving guidelines of major professional societies.
Guidelines consistent with the routine use of Rh D immune globulin in all cases of early pregnancy loss and abortion care
As of the publication date of this editorial, the American College of Obstetricians and Gynecologists (ACOG) Practice Bulletin on prevention of Rh D alloimmunization provides the following guidance based on consensus and expert opinion2:
- “Although the risk of alloimmunization is low, the consequences can be significant, and administration of Rh D immune globulin should be considered in cases of spontaneous first trimester miscarriage, especially those that are later in the first trimester.”
- “Because of the higher risk of alloimmunization, Rh D-negative women who have instrumentation for their miscarriage should receive Rh D immune globulin prophylaxis.”
- “Rh D immune globulin should be given to Rh D-negative women who have pregnancy termination either medical or surgical.”
The Society of Obstetricians and Gynaecologists of Canada (SOGC) recommends that, “After miscarriage or threatened abortion or induced abortion during the first 12 weeks of gestation, non-sensitized D-negative women should be given a minimum anti-D of 120 µg.”3
The liberal use of Rh D immune globulin in all cases of early pregnancy loss and abortion care is based, in part, on the following considerations:
- the recognized safety of Rh D immune globulin administration2,3
- the report that fetal megaloblasts may express Rh antigen as early as 38 days of gestation4
- the observation that 0.1 mL of Rh D-positive red cells may provoke an immune response in some Rh D-negative patients5-7
- the estimate that in some patients with threatened miscarriage a significant quantity of fetal blood may enter the maternal circulation.8
Guidelines that suggest restricted use of Rh D immune globulin before 7 to 8 weeks’ gestation
The Reproductive Care Program of Nova Scotia guideline from 2022 notes that “the benefits of administering Rh immune globulin before 8 weeks gestation have not been demonstrated.” Given the burden of Rh testing and Rh D immune globulin administration they suggest that clinicians may withhold Rh testing and Rh D immune globulin administration in cases less than 8 weeks’ gestation (less than 56 days) for spontaneous, threatened, or medication abortions if there is reliable pregnancy dating.9
The Dutch Association of Abortion Specialists guidelines from 2018 suggest to not provide Rh D immune globulin treatment in the following clinical situations: patients under 10 weeks’ gestation with spontaneous miscarriage or patients under 7 weeks’ gestation having an induced abortion.10
Continue to: Guidelines that suggest restricted use of Rh D immune globulin before 10 to 12 weeks’ gestation...