The study will consist of a matched case-control series and a retrospective review of SCBU charts of neonates with NH reaching exchange transfusion threshold. The SCBU database will be searched for neonates born at ≥ 28 weeks of gestation hospitalized for phototherapy between January 2009 and December 2014; charts will be manually researched to identify study participants which will be classified as NH reaching exchange transfusion threshold (cases) or as NH within moderate threshold (controls). Additionally neurological signs compatible with ABE will be searched in the clinical notes and coded as present/absent. Cases discharged alive from the SCBU will be traced back to evaluate their clinical and neurocognitive long term outcome. Each case will be matched with a moderate NH control from the same clinic, sex, gestational age and season of birth and hospitalized within the same month.