Abstract
INTRODUCTION: Targeted routine antenatal anti-D prophylaxis (RAADP) was introduced in Finland in 2014. The aim of this study was to assess the prevalence of anti-D immunizations among pregnant women and the severity of hemolytic disease of the fetus and newborn (HDFN) in affected pregnancies 10 years after RAADP was added to the national prevention program in the context of a rapidly declining birthrate in Finland. MATERIAL AND METHODS: A nationwide, retrospective cohort study included all RhD-negative pregnancies in Finland between 2014 and 2023. Information on antenatal screening was obtained from the Finnish Red Cross Blood Service database, and obstetric and neonatal data from hospitals' records. Primary outcomes were prevalence of anti-D immunization and severity of HDFN defined as severe (intrauterine transfusion, IUT), moderate (neonatal exchange transfusion/intravenous immunoglobulin, IVIG/top-up transfusion), and mild (phototherapy). The secondary outcome was the effect of declining birth rates on the absolute numbers of anti-D pregnancies. RESULTS: The study included a total of 518 pregnancies of 383 women with anti-D (367 pregnancies with RhD-positive fetus/neonate). In 10 years, the prevalence of anti-D among RhD-negative pregnant women declined from 1.33% to 0.48% (reduction of 64%), and of severe HDFN from 0.20% to 0.06% (reduction of 72%). For an RhD-positive fetus, the risk of severe HDFN was 17.7% (95% CI 13.9% to 22.0%), with an overall survival rate of 90.8%. For a RhD-positive neonate not treated with IUTs, the risks of moderate and mild HDFN were each 33.0% (95% CI 24.4% to 42.6%). In addition to the effect of RAADP, the actual number of anti-D cases decreased by 34.0% due to the 24% fall in the birth rate during the study period. CONCLUSIONS: Ten years after the introduction of targeted RAADP, the prevalence of anti-D immunizations was reduced by more than half. Declining birth rates further reduce overall case numbers but do not lessen the complexity of care needed. A significant proportion of anti-D pregnancies still require close monitoring or intervention. Optimizing screening strategies, referral pathways, and readiness for neonatal treatment remains essential in the evolving landscape of HDFN prevention and management.