Blood group AB is associated with poor outcomes in infants with necrotizing enterocolitis.

BACKGROUND: Necrotizing enterocolitis (NEC) is a neonatal disease associated with necrosis and perforation of the bowel. We investigated the association between blood group and NEC outcomes and the potential contribution of fetal-maternal blood group incompatibility.

METHODS: Retrospective study including all preterm-born infants with NEC (≥ Bell's stage IIa) admitted to our NICU between January 2008 and October 2019. We analyzed the association between infants' blood groups and fetal-maternal blood group incompatibility with Bell stage severity, need for surgery, and mortality due to NEC.

RESULTS: We included 237 NEC patients. In univariable analyses both AB blood group and fetal-maternal blood group incompatibility increased infants' risk of severe outcomes, with odds ratios (OR) ranging from 6.57 to 12.06 and 1.97 to 2.38, respectively. When adjusted for gestational age only AB blood group remained significant with OR 7.47 (95% confidence interval, 1.95-28.53, P = 0.003), 12.37 (2.63-58.20, P = 0.001), and 8.16 (2.28-29.14, P = 0.001) for NEC Bell's stage III, need for surgery, and NEC related mortality, respectively. Blood group incompatibility adjusted for gestational age was not related to worse outcomes with OR 1.84 (0.87-3.89, P = 0.11, 2.08 (0.98-4.41, P = 0.06) 1.52 (0.68-3.42, P = 0.31), for NEC Bell's stage III, need for surgery, and NEC related mortality, respectively.

CONCLUSION: Our data confirm an association between blood group AB and worse outcomes in NEC infants, but this is not based on fetal-maternal blood group incompatibility.