Mapping obstetric biobanks: A scoping review highlighting gaps in the study of alloimmunized pregnancies

BACKGROUND: Maternal red cell alloimmunization can cause hemolytic disease of the fetus and newborn (HDFN), yet prediction of disease severity remains limited. Biobanks that link pregnancy biospecimens with clinical and laboratory data could accelerate translational research; however, the landscape of relevant obstetric biobanks has not been mapped. STUDY DESIGN AND METHODS: We conducted a scoping review following Joanna Briggs Institute methodology. MEDLINE, Embase, and CENTRAL were searched from January 2005 to May 20, 2025 for publications describing the establishment, structure, or operation of obstetric biobanks. Abstract screening, text review, and data extraction were conducted in duplicate. Findings were synthesized narratively. RESULTS: Of 2482 records screened, 29 publications met inclusion criteria, representing 21 unique biobanks across 18 countries and 6 continents. Most were conducted in high-income countries (n = 13) and were multicenter (n = 17). Biobanks primarily focused on environmental and genetic influences on development (n = 14) and pregnancy outcomes (n = 7), with no identified biobanks dedicated to alloimmunization. The types of maternal biospecimens collected varied, including whole blood (n = 19), plasma (n = 18), serum (n = 16), and urine (n = 16), with frequent collection of placental tissue (n = 14) and cord blood (n = 16). All biobanks incorporated maternal clinical variables (n = 21), whereas paternal (n = 10) and laboratory (n = 9) variables were less common. Only one biobank explicitly collected immunohematology variables (e.g., RhD status and maternal alloantibodies). CONCLUSION: Obstetric biobanks have the potential to accelerate discovery in alloimmunized pregnancies, but existing biobanks rarely capture immunohematologic variables. Integrating standardized immunohematology variables and paired maternal-fetal-paternal sampling into future initiatives could facilitate translational research on alloimmunization and HDFN.