The prevalence of ABO-HDN
From November 2016 to April 2020, 471 (6.03%) infants from 7 810 live births were confirmed to have ABO haemolytic disease. Among them, 46.50% (219/471) infants were male, 8.07% (38/471) were premature, 4.88% (23/471) weighed less than 2 500 g and 45.44% (214/471) were first-borns. Of newborns, 42.04% (198/471) were admitted with jaundice occurring in <24 hours and the median postnatal age of admission (days) was two (interquartile range (IQR) was one-three days; 15 neonates were re-admitted, with a median age at re-admission of 10 days, and IQR of 8-12 days). The baseline demographic characteristics of the newborns with ABO HDN are presented in Table 1. Moreover, two neonates were diagnosed with Trisomy 21 syndrome and Gilbert syndrome, respectively, in addition to ABO HDN. Four mother-infant pairs were also diagnosed with Rh(D) incompatibility. Twenty-seven (5.73%) neonates had severe hyperbilirubinemia (TSB ≥ 342 μmol/L) of which five (18.52%) had extreme hyperbilirubinemia (TSB ≥ 428 μmol/L, one of the patients was also diagnosed with Gilbert syndrome). Finally, 99.15% (467/471) of infants underwent intervention with phototherapy, 57.54% (271/471) underwent invasive treatments (intravenous immunoglobulins), and only two were subjected to ET.
Excluding subjects with congenital disease and combined with Rh(D) incompatibility, 465 cases whose mothers were all blood group O were identified, of which 49.46% (230/465) had blood type A and 50.54% (235/465) had blood type B. Median peak TSB was 206.80 μmol/L (IQR was 160.08 to 262.16 μmol/L), and mean Hb was 142.58 g/L (standard deviation (SD) was 23.76 g/L). No significant difference was found between the O-A incompatibility group and the O-B incompatibility group in Hb and peak TSB. Sixty-seven (14.41%) newborns were DAT positive. DAT-positive neonates (mean Hb value was 133.00 g/L) had lower Hb levels than DAT-negative neonates (mean Hb value was 144.50 g/L) (P <0.05) (Fig. 2a), but no difference was observed in peak TSB between the two groups. In addition, the DAT positive rate of group A was higher than that of group B (P <0.05) (Fig. 2b).
The peak TSB was significantly different between the several different age groups of postnatal admission (P <0.001), and the median peak TSB level was higher in the older postnatal age of admission group than in the younger group between each two groups, except the two-three days group and ≥ 14 days group, and the 4-13 days group and ≥ 14 days group (Fig. 4a). Furthermore, the correlation coefficient between the postnatal age of admission and peak TSB levels was 0.54 (P <0.001) (Fig. 3). The severe hyperbilirubinemia groups had a later postnatal age of admission than ABO HDN neonates that did not develop severe hyperbilirubinemia (P <0.001) (Fig. 4b). In addition, neither gender, gestational age, birth weight, the mode of delivery, blood type, or DAT results were related to severe hyperbilirubinemia (P >0.05).