Developing monoclonal anti-D was also discussed as a potential solution. Participants considered the scientific promise of monoclonal anti-D, as well as the regulatory, ethical, and access issues that must be addressed if such products are to contribute meaningfully to global HDFN prevention. A recurring theme was that innovation must not widen existing inequities; rather, new solutions should be developed with the needs of the most affected populations in mind.

Parallel workshops translated these discussions into practical next steps. Topics included advocacy and policy pathways, research ethics, plasma collection and donor recruitment, patient and public involvement, and standards regarding anti-D dosage. In workshops, participants identified barriers, including limited data, low awareness, procurement challenges, cost, supply chain fragility, and fragmented clinical guidelines. They also identified solutions, including stakeholder engagement, stronger guidelines, community involvement, patient advisory structures, improved data systems, and international collaboration.

One key outcome was the establishment of two research consortia: one focused on polyclonal anti-D and one on monoclonal anti-D. These consortia will support coordinated research, implementation planning, and evidence generation for sustainable anti-D production and utilization.

Day 2: Worldwide variation in clinical practice

The second day focused on current clinical practice, including international variation in HDFN screening, laboratory diagnostics, antenatal treatment, and postnatal management.

Keynote lectures provided international perspectives on which pregnant women should be screened for which red blood cell antibodies, how laboratories can identify high risk pregnancies, how antenatal treatment has evolved, and variations in postnatal management.

Questionnaire results and panel discussions highlighted substantial differences between countries. These included variations in: the timing of first antibody screening, repeat screening strategies, screening-cell composition, fetal genotyping using cell-free fetal DNA, referral thresholds, fetal anemia monitoring, intrauterine transfusion usage, postnatal IVIg use, bilirubin thresholds, and exchange transfusion practices.

Some of this variation reflects differences in resources, infrastructure, and national guidelines. However, these variations also revealed important opportunities for international learning. Participants considered where harmonization may be useful, where local adaptation is necessary, and where more evidence is needed before firm recommendations can be made.

Aw research agenda was developed covering four broad domains: screening, diagnostics, antenatal management, and postnatal management. Priorities included improving antibody screening technologies, understanding the role of low-frequency antigens, integrating blood group determination into non-invasive prenatal testing, distinguishing immune from passively-administered anti-D, and evaluating cost-effective screening strategies.

For diagnostics, participants highlighted the need for better tools to predict clinically-significant disease, including quantitative antibody testing, bioassays, fetal genotyping, and biomarkers of fetal anaemia. For antenatal management, priorities included evaluating treatment options (e.g., IVIg), improving severe disease prediction, comparing intrauterine transfusion techniques, and strengthening long-term follow-up. Postnatal care priorities included the timing of delivery, the role of IVIg, exchange transfusion practices, bilirubin-related outcomes, and registries for acute bilirubin encephalopathy and kernicterus spectrum disorder.

Moving from knowledge to action

The conference made clear that HDFN prevention and treatment cannot be advanced solely through isolated efforts. The anti-D divide is a global challenge requiring coordinated action involving transfusion medicine, obstetrics, neonatology, laboratory medicine, public health, regulation, patient advocacy, and policy.

Nonetheless, progress is possible. Existing knowledge, emerging technologies, patient experience, and international collaboration can be synergized to build practical solutions. The challenge is to translate the momentum of the conference into research, policy, and implementation.

The 2nd International Alloimmune Conference closed with a clear message: HDFN remains preventable, but prevention requires effective systems. Strengthening those systems (e.g., from increasing anti-D supply to improving screening, diagnosis, antenatal care, and postnatal treatment) is essential if HDFN is to become completely preventable.