Prevalence of “unexpected antibodies” in the antenatal women attending the Government Maternity Hospital, Tirupati

Background: All antibodies to red cell antigens, other than naturally occurring anti-A and anti-B are considered unexpected. They can be either alloantibodies or auto antibodies. In pregnant women, these antibodies may cross the placenta and cause haemolytic disease of the foetus and newborn (HDFN). Timely detection of such antibodies in antenatal women is essential for early management of HDFN. Methods: A prospective cross-sectional study was carried out on 2060 multiparous pregnant women attending the Government Maternity Hospital, Tirupati to detect prevalence of unexpected antibodies. The women were grouped and typed for ABO and rhesus (Rh) D antigens by tube method and screened for alloantibodies by column agglutination technology. The medical and detailed obstetric history of these women were reviewed. Results: The overall prevalence of alloantibodies was 1.1%. There was a statistically significant difference between alloimmunization rates in the Rh D-antigen negative and D-antigen positive women (12.8% versus 0.3%). The antibodies detected in this study were, anti-D (63.8%), anti-D+C (13.7%), anti-C, anti-E, anti-M, anti-Lea , and anti-Leb (4.5% each). Anti-D contributed to 77.3% of total alloimmunization in this study. Conclusions: In spite of the introduction of prophylactic Rh- immunoglobulin, anti-D (77.3%) is still a common antibody identified in the antenatal women of our region. In developing countries like India, universal antenatal antibody screening, though desirable may not be justified at present as the cost and infrastructure required would be immense. However, it is necessary to impose properly formulated protocols to screen at least the pregnant women with adverse obstetric history.