The importance of antenatal prevention of RhD immunisation in the first pregnancy

Abstract

Background: The aim of this study was to examine which pregnancies are associated with RhD immunisation and haemolytic disease of foetus and newborn (HDFN) when postnatal RhD prophylaxis is applied.

Material and methods: This retrospective cohort study included pregnancies with RhD immunisation; each of the pregnant women received anti-D immunoglobulin after delivery, miscarriage or invasive antenatal diagnostic procedures. For each pregnancy we analysed the order of pregnancy that caused immunisation as well as the order of the monitored pregnancy and whether the anti-D antibodies caused HDFN.

Results: Anti-D antibody was detected in 1.2% of RhD-negative pregnancies. Out of 89 monitored pregnancies, 56 (63%) were immunised by the first pregnancy, 21 (24%) by the second one, and 12 (13%) by subsequent pregnancies. HDFN occurred in 28 cases; 25 of them were the consequence of the immunisation in the first pregnancy. The most severe cases of HDFN, perinatal death (n=2) and intrauterine transfusion (n=7) were consequence of immunisation during the first pregnancy. Significantly more cases of HDFN were caused by immunisation in the first pregnancy than by immunisation in subsequent pregnancies (χ(2)=12, p<0.01).

Conclusion: RhD immunisation could be reduced in more than half cases by administering anti-D immunoglobulin at the beginning of the third trimester of pregnancy, especially the first pregnancy.