Routine antenatal Rhesus D immunoglobulin prophylaxis: the results of a prospective 10 year study

Objective To assess the clinical and financial impact, and identify the pro blems, of providing routine antenatal RhD immunoglobulin prophylaxis for Rh esus D negative nulliparae. Design A retrospective (1980-1986) and prospective (1987-1996) comparison b etween two similar populations, one population with nulliparae offered rout ine RhD immunoglobulin 500 IU prophylaxis at 28 and 34 weeks of gestation p art way through the study period, and the other population not offered prop hylaxis at any time. Setting Obstetric units in two counties (three health districts) with simil ar annual numbers of maternities and the Regional Blood Transfusion Service antenatal serology laboratory. Participants Non-sentisitised Rhesus D negative pregnant nulliparae. Interventions Intramuscular RhD immunoglobulin 500 IU at 28 and 34 weeks of gestation to eligible women booked for confinement in one county; the inte rvention not offered in the other county. Main outcome measures 1. Rhesus D sensitised second pregnancy rate; 2. succ ess in providing prophylaxis to eligible women; 3. serology laboratory acti vity changes; 4. potential savings from the prophylaxis programme. Results Prophylaxis significantly reduced iso-immunisation in the next preg nancy when compared with historical (OR 0.28, CI 0.14-0.53; P < 0.0001) and contemporary controls (OR 0.43, CI 0.22-0.86; P = 0.02). However success a t achieving comprehensive prophylaxis was disappointing, with only 89% of e ligible women receiving the first injection, 74% both injections, and for o nly 29% were both at the correct gestation. Fifty-two percent of women deli vered after 40 weeks of gestation, beyond the period of adequate prophylaxi s protection. The savings in antenatal interventions, neonatal care and pos sible long term ill-health that result from very preterm birth should be co nsiderable. Conclusion Routine prophylaxis for nulliparae significantly reduces the inc idence of sensitised next pregnancies with consequent savings, and its adop tion nationwide should be encouraged. A programme offering antenatal prophy laxis for all Rhesus D negative women is unlikely to be economic. Improveme nt in uptake of prophylaxis is needed; alternative administration strategie s should be explored.