Forecasting the rate of hemolytic disease of the fetus and newborn in the United States based on recent trends in prehospital transfusion

BACKGROUND: As prehospital transfusion becomes more common in the United States (US), cases of hemolytic disease of the fetus and newborn (HDFN) might increase. This study forecasted the number of HDFN cases in 2029 resulting from RhD-positive prehospital transfusions. STUDY DESIGN AND METHODS: A regression was performed on the number of females of childbearing potential (FCP) who received RhD-positive prehospital transfusions between 2020 and 2024 in the US to forecast the total number of FCPs who would receive transfusions in 2029. Then, a model using current nativity and population demographics was used to calculate the regional rate of HDFN in 2029 (Model 1). In addition, the frequency of transfusing FCPs in the four US census regions in 2029 was varied based upon the regional uptake of prehospital low titer group O whole blood transfusion between 2024 and 2025 (Model 2) and the uptake of prehospital transfusion by ground ambulances between 2019 and 2026 (Model 3). Each model was instantiated 500 times. RESULTS: It was forecasted that 779 FCPs would receive prehospital transfusions in 2029 throughout the US. In Model 1, the number of years required for one case of HDFN to occur was calculated to range from 0.5 (South)-20.0 (Northeast). When the regional frequency of providing prehospital transfusions was varied, the number of years required for one case of HDFN to occur ranged from 0.6 (South)-13.5 (Northeast) (Model 2), and between 0.7 (South)-4.6 (Northeast) (Model 3). DISCUSSION: As prehospital transfusions increase, the risk of HDFN is predicted to also increase.