Application of IgG antibody titer and subtype in diagnosis and severity assessment of hemolytic disease of the newborn

BACKGROUND: To analyze the effect of different times of pregnancy of type O pregnant women on the occurrence of ABO hemolytic disease of the newborn (ABO-HDN). METHODS: From December 2018 to December 2021, 725 pregnant women with O blood group (husbands with non-O blood group) who met the inclusion criteria were collected. There were 116 cases of ABO-HDN, which were summarized and analyzed. The pregnant women were divided into primigravida and non-primigravida groups. The influence of the number of pregnancies on the occurrence of ABO-HDN was compared, and the antibody titer of pregnant women with type O blood was monitored. The relationship between antibody titer and HDN in pregnant women was analyzed by hemolysis test and indirect bilirubin concentration. RESULTS: In the primigravida group, 0 patients with HDN had a titer ≤1:64, 8 (8/26) had a titer of 1:128, 9 (9/20) had a titer of 1:256, 2 (2/4) had a titer of 1:512, and 2 (2/3) had a titer >1:512. In the non-primigravida group, there were 0 cases with a titer ≤1:64, 32 cases (32/78) with a titer of 1:128, and 26 cases (26/46) with a titer of 1:256. The number of cases of ABO incompatibility in maternal and infant groups with different titers of IgG anti-A (B) antibody were 377 cases in the <1:64 group, 130 cases in the 1:64 group, 104 cases in the 1:128 group, 66 cases in the 1:256 group, 32 cases in the 1:512 group, and 16 cases in the >1:512 group. The positive rates of ABO-HDN were 0.0% (0/0), 0.0% (0/0), 38.5% (40/104), 53.0% (35/66), 81.3% (26/32) and 93.8% (15/16), respectively, and the difference was statistically significant (P<0.05). CONCLUSIONS: The occurrence of ABO-HDN was not significantly related to the blood type of the pregnant woman’s husband. Therefore, in order to reduce the degree of hemolysis and avoid the occurrence of bilirubin encephalopathy or even death, pregnant women with antibody titer >1:64 in second or subsequent pregnancies should be closely monitored.