Rhesus prophylaxis

Because anti-D can cause haemolytic disease* in the fetus, rhesus prophylaxis was introduced at the end of the 1960s. In this treatment, a small dose of anti-D, such as Rhophylac 300, is administered to the mother. This breaks down any of the fetus’ erythrocytes that may enter the mother’s blood stream, thus preventing the mother from being immunized against the fetus’ RhD factor. At birth, a newborn’s blood group is determined from the umbilical cord blood. If the newborn is RhD-positive, Rh prophylaxis is administered to an RhD-negative mother.
According to maternal care guidelines in the past, Rh prophylaxis has been administered to all RhD-negative pregnant women in the 28th – 30th week of pregnancy, independent of the rhesus status of the unborn child. Rh prophylaxis is therefore administered to some pregnant women without actually being medically necessary. This affects around 40% of RhD-negative pregnant women.

Why should rhesus prophylaxis be used only when needed?

The Rh prophylaxis treatment is very safe. Even so, pregnant women occasionally express concern since Rh prophylaxis is a blood product. It is produced from the blood of donors who have previously immunized themselves against the Rhesus-D factor. Although anti-D immunoglobin is an exceptionally infection-proof blood product, transmission of infection cannot be ruled out for all batches and for all pathogens. Human anti-D immunoglobin can also rarely (frequency between 1:1000 and 1:10,000) cause hypersensitivity reactions1.

* Anti-D used to be a common cause of haemolytic disease. The unborn child receives a large amount of antibodies from the mother through the placenta. This will protect the newborn from infection. In the case of anti-D, however, this means that the fetus’ erythrocytes are broken down more quickly. This leads to fetal anemia, which in the worst case can lead to the death of the unborn child.
In less severe cases, babies can be born with an increased incidence of neonatal jaundice, although this usually responds well to treatment.
It is important to discover if the mother will form anti-D and other blood group antibodies during pregnancy. Two antibody screening tests are therefore usually carried out during pregnancy, one in early pregnancy and another between the 24th and 27th weeks of pregnancy. Other, mostly harmless antibodies will also give a positive test in addition to anti-D, so the vast majority of pregnancies proceed normally even if the antibody test is positive.

  1. Prof. Dr. med. Tobias J. Legler, Anti-D-Prophylaxe bei RhD-negativen Frauen – Hämotherapie www.drk-haemotherapie.de