Abstract
Objective: To investigate the frequency of Rh–ive patients and effectiveness of Rh immunization, comparing antibody titer before and after immunization.
Methodology: This comparative cross sectional study was carried out at the Department of Obstetrics and Gynecology, Fatima Hospital, Baqai Medical University, Karachi, from January 2013 to June 2014. Fifty primigravid women with Rh –ve blood group and their husbands with Rh +ve blood group were included in the study. The antibody titer through indirect Coomb’s test was checked in all the patients at 28 weeks gestation. If –ve titers, AntiD 1500 IU for prophylaxis was given between 28-34 weeks. After delivery, if baby was Rh +ve, AntiD was given within 72 hrs. Antibody titer was again measured at 6 weeks postpartum.
Results: Out of 50 primigravidae, 68% were B –ve, 30% were A –ve and 2% were O –ve. At 28 wks, 78% showed 1:4 dilution, 22% showed 1:8 dilution and no one reached up to 1:16 dilution. Six weeks postnatally, when antibody titers were repeated, there was no significant increase in titer.
Conclusion: The antibody titers are independent of AntiD IgG and immunization did not affect the level of antibody titer. Anti D IgG is thus the only and most effective prophylaxis against the Rh incompatability disease.

Key words: Immunoprophylaxis, Anti D, Antibody titre, Rh incompatibility