Correlation between immunoglobulin G anti-A/B titer and neonatal hemolytic disease in pregnant women with O-type blood group from ABO blood group incompatibility couples

Objective To investigate the correlation between immunoglobulin (Ig) G anti-A/B titer and neonatal hemolytic disease (HDN) in pregnant women with O blood group from ABO blood group incompatibility couples. Methods From February 2015 to August 2017, a total of 104 pregnant women with O-type and Rh-positive blood group who underwent prenatal blood group antibody test because of couples with ABO blood group incompatibility in the Blood Type Reference Laboratory of Blood Center Shandong Province were selected as subjects. The average age of pregnant women were (26.5±6.8) years. According to gravidity of these pregnant women, they were divided into 3 groups : first pregnancy group (n=31), twice pregnancy group (n=35) and≥3 times pregnancy group (n=38). Micro-column method were performed to detect the ABO blood group of the couples, the Rh blood group and titer of serum IgG anti-A/B of pregnant women. The umbilical vein blood samples of newborns were tested by direct anti-globulin test, free antibody test and antibody elution test. The positive rate of serum IgG anti-A/B in pregnant women, the incidence of ABO-HDN in newborns, as well as the correlation among gravidity, serum IgG anti-A/B titer and incidence of ABO-HDN were calculated, respectively. The age and gestational age of pregnant women among 3 groups were compared by variance analysis. The positive rate of serum IgG anti-A/B of pregnant women among 3 groups, and the incidence of ABO-HDN of newborns among different maternal serum IgG anti-A/B titer, were compared by chi-square test, respectively. And further pairwise comparison of above data used Bonferroni method to adjust the significance level. The correlation among the gravidity maternal, serum IgG anti-A/B titer, and neonatal ABO-HDN incidence were analyzed with Spearman rank correlation analysis. The procedures followed in this study were in accordance with the standards established by the Medical Ethics Committee of Blood Center Shandong Province, and this study was approved by the committee. All the subjects signed the informed consents for clinical trials. Results ① In this study, ABO blood group of all 104 pregnant women were O-type, and Rh blood group were positive. The ABO blood group of their husbands included 41 cases of A-type, 48 cases of B-type and 15 cases of AB-type. The ABO blood group of the newborns included 45 cases of A-type, 50 cases of B-type and 9 cases of O-type. ② Among the 104 pregnant women in this study, the total positive rate of serum IgG anti-A/B was 65.4% (68/104). The positive rates of serum IgG anti-A/B of pregnant women in the first, twice, ≥3 times pregnancy groups were 45.2% (14/31), 65.7% (23/35) and 81.6% (31/38), respectively. The overall difference was statistically significant among the 3 groups (χ2=10.007, P=0.008). The positive rate of serum IgG anti-A/B of pregnant women in the ≥3 times pregnancy group was higher than that of the first pregnancy group, and the difference was statistically significant (χ2=9.981, P=0.002). But there was no significant difference between the first group and ≥3 times pregnancy group (χ2=9.981, P=0.002). ③ Among 104 newborns in this study, the incidence of ABO-HDN was 17.3% (18/104). The incidences of ABO-HDN in newborns of maternal serum IgG anti-A/B titer 0.05). ④ In this study, the gravidity of 104 pregnant women were positively correlated with their serum IgG anti-A/B titers, which were positively correlated with the incidences of ABO-HDN in their newborns, and the maternal serum IgG anti-A/B titers was positively correlated with the incidences of ABO-HDN in their newborns (r=0.423, P=0.035; r=0.473, P=0.031; r=0.491, P=0.021). Conclusions The serum IgG anti-A/B positive rate of O-type blood group pregnant women with multiple pregnancies from ABO blood group incompatibility couples increased, and the risk of ABO-HDN in their newborns was high. Key words: Blood group incompatibility; ABO blood-group system; Pregnant women; Immunoglobulin G; Erythroblastosis, fetal