Introduction
Haemolytic disease of the foetus and newborn(HDFN) due to
maternofoetal blood group incompatibility was once a significant factor
in perinatal morbidity and mortality [1]. However, the widespread
adoption of antenatal and postpartum use of Rh immune globulin in most
western countries has resulted in a decrease in the incidence of Rh(D)
alloimmunization [1, 2]. ABO incompatibility has become the most
common cause of haemolytic disease of the newborn (HDN) [3].
HDN is an immune-mediated haemolytic disease, almost exclusively limited
to ABO neonates with blood groups A or B delivered by women with group
O. ABO-incompatible newborns with haemolytic disease are at risk for
various degrees of anaemia and subsequent hyperbilirubinemia caused by
immune-induced haemolysis [4]. Toxic bilirubin can occasionally
cross the immature neonatal blood-brain barrier, resulting in
kernicterus and subsequent life-long disabilities such as hearing
impairment [5]. In a previous study, approximately one-third of
ABO-incompatible newborns had significant hyperbilirubinemia and
required phototherapy [6]. Phototherapy provided by modern equipment
has been proven to be effective by decreasing the need for exchange
transfusion (ET) in the treatment of hyperbilirubinemia [5].
However, severe subjects with dramatic haemolysis and
hyperbilirubinemia, which require ET, have also been reported in
clinical studies [7, 8]. In addition, the routine practice of early
discharge of newborns at postnatal <48 hours lead to a higher
readmission rate for hyperbilirubinemia within 14 days of birth and
brings extra unnecessary expense [9, 10]. Among the identified
causes of hyperbilirubinemia, ABO incompatibility was the most common
[11].
ABO incompatibility cannot always be avoided, but the severity of ABO
incompatibility in neonates varies greatly from region to region.
Italian mothers experience a major ABO incompatibility with their
newborns at a rate of approximately 11%, but haemolytic disease occurs
in only 2.5% of births [12]. Both ratios are higher in Blacks, with
the former farther than the latter [13]. Meanwhile other studies
show that Asians have an increased likelihood of extreme neonatal
hyperbilirubinemia and hospital readmission rates due to jaundice [9,
14]. However, the circumstance of ABO incompatibility remains unknown
in northern China.
Our objective was to estimate the frequency of ABO incompatibility among
infants, survey the incidence of haemolytic disease due to ABO
incompatibility, compare the risk of haemolysis and jaundice between
O-A/B and DAT-pos/neg subgroups, and assess the proportion of neonates
developing ABO-incompatible haemolysis with neonatal severe
hyperbilirubinemia in a single institution.