Introduction: The relationship between ethnicity and racial disparities in neonatal outcomes has not been fully explained to date (Matoba, N. et al. Semin Perinatol. 2017; 41(6):354-9. Black infants born < 32 weeks of gestation more often have hypoxemia than white infants and pulse oximetry seems to overestimate their arterial oxygen saturation levels (SaO₂) (Vesoulis, Z. et al. J Perinatol. 2022;42(1):79-85). The aim of this study was to determine if black, preterm infants were exposed more frequently to hypoxia compared to white infants and had a higher level of oxidative damage as estimated by carboxyhaemoglobin (COHb) levels.

Methods: The median SaO₂ over the first seven days of life was calculated in infants born < 32 weeks of gestational age and adjusted for differences in the amount of available data for each infant (adjusted SaO2). The maximum COHb level for the first three days was also recorded.

Results: Two thousand and sixty blood gases from 87 infants (38 black) with a median (IQR) gestational age of 26.4 (24.6-28.3) weeks were analysed. The adjusted median (IQR) SaO₂ was significantly lower in black infants [46.4 (30.3-63.1) %] compared to white infants [59.7 (53.7 - 74.7) %, p=0.002]. The highest COHb was significantly related to the adjusted median SaO₂ in all infants (r=-0.406, p<0.001) and in black (r=-0.392, p=0.018) and white (r=-0.463, p=0.003) infants.

Conclusions: Preterm, black infants compared to white infants had lower median SaO₂ levels. Lower saturation levels were associated with higher maximum carboxyhaemoglobin indicating a higher risk of oxidative stress. These findings may partially explain the racial disparities observed in neonatal outcomes.