Purpose: To identify if there is an association between foetal haemoglobin (HbF) concentration and retinopathy of prematurity (ROP) in very preterm infants.Patients and methodsProspective cohort study. Infants born <32 weeks' gestational age or <1501 g in two tertiary neonatal units between January 2012 and May 2013 (n=42) were enrolled. HbF and adult haemoglobin (HbA) concentrations were measured using high-pressure liquid chromatography from blood samples sent as part of routine neonatal care once routinely requested laboratory tests had been performed. Clinical data were obtained from case notes. We calculated odds ratios (ORs) (95% confidence intervals (CIs)) to quantify the relationship between initial and mean %HbF with ROP severity (none, stages 1-3).ResultsA total of 42 infants were recruited: mean gestation 28.0 weeks (SD 1.91); mean birth weight 1042 g (SD 264). Six infants died before ROP screening; 14/36 developed ROP (39%); and 22/36 (61%) did not. Infants who developed ROP had similar initial %HbF (83.3 vs 92.3%, P=0.06), but significantly lower mean %HbF (61.75 vs 91.9%, P=0.0001) during their inpatient stay than those who did not develop ROP. In ordinal logistic regression models adjusted for birth weight, gestation and transfusion volume, mean post-natal %HbF was negatively associated with ROP severity: adjusted OR 0.94 (0.90-0.99), while initial %HbF at birth was not: adjusted OR 1.05 (0.97-1.16).ConclusionReplacing HbF by HbA during transfusion may promote ROP development by rapidly increasing oxygen availability to the retina. Conversely, maintaining a higher %HbF may be a protective factor against ROP.Eye advance online publication, 26 May 2017; doi:10.1038/eye.2017.76.