Fetal hemoglobin fraction is correlated to the risk of prematurity complications

Background: Fetal hemoglobin (HbF) plays a critical role in the progressive adaptation to the postnatal oxygen-rich environment in preterm infants due to its peculiar properties and its postnatal decrease has been associated to the combined adverse effects of increasing tissue hyperoxia and decreasing antioxidant defenses in preterm infants. Purpose: We aimed to assess the association between HbF fractions and the risk of bronchopulmonary dysplasia (BPD) intraventricular hemorrhage (IVH), and retinopathy of prematurity (ROP). Methods: We studied 166 preterm infants with a gestational age of 27.1 ± 1.6 weeks. One hundred and twenty-six infants (74%) had no or mild BPD, and 40 (24%) moderate to severe BPD. One hundred and forty-three infants (86%) had no or grade 1 IVH, and 23 (14%) grade 2-4 IVH. One hundred and thirty (80%) had no ROP, and 32 (20%) had any grade ROP. HbF fractions were recorded during the first seven days of life, at 14, 21, and 28 days of life, and 31, 34, and 36 weeks of postmenstrual age. Mean values during the first week of life (HbF1st week) and at 31, 34, and 36 weeks (HbF31-36 weeks) were calculated. Results: Logistic regression analysis showed that: HbF31-36 weeks decreased the risk of moderate to severe BPD (OR 0.944, 95% CI 0.911-0.977; p = 0.001); female sex (OR 0.278, 95% CI 0.093-0.832; p = 0.022) and HbF1st week (OR 0.949, 95% CI 0.901-0.999; p = 0.048) decreased the risk of grade 2-4 IVH; and HbF1st week (OR 0.958, 95% Cl 0.919-0.998; p = 0.042) and HbF31-36 weeks (OR 0.956, 95% CI 0.927-0.986; p = 0.004) decreased the risk of any grade ROP. Conclusion: Low HbF fractions were associated with increased risk of moderate-to severe BPD, grade 2-4 IVH, and any grade ROP. These results confirm previous findings and support the importance of minimizing blood sampling from these fragile patients.