Assessing blood carboxyhemoglobin levels as an early predictor of phototherapy in ABO incompatible newborns

Background This study aimed to evaluate blood carboxyhemoglobin (COHb) levels as an indicator of hemolysis and as an early predictor of phototherapy requirement in newborns with blood type A or B born to mothers with blood type O. Methods In this prospective observational study, enrolled infants were divided into two groups: Group 1 comprised newborns with maternal blood type O and infant blood type A or B, while Group 2 consisted of newborns born to mothers without blood type O. Total serum bilirubin and carboxyhemoglobin levels were assessed from cord blood samples at birth and venous blood samples at 24 h of life and compared between groups. None of the infants required intravenous immunoglobulin therapy or blood transfusion. Results A total of 100 term infants were included. Mean carboxyhemoglobin levels in cord blood and at 24 h of life were significantly higher in Group 1 compared with Group 2 (0.55 vs 0.48, p = 0.04; 0.69 vs 0.36, p = 0.002, respectively). The onset of phototherapy occurred significantly earlier in Group 1 than in Group 2 (48 vs 90 h, p = 0.01). Conclusion Elevated carboxyhemoglobin levels were observed in newborns with ABO incompatibility, and higher levels were associated with an earlier requirement for phototherapy.