THY1 and bronchopulmonary dysplasia: Severe BPD was positively associated with %CD34+ (beta-coefficient = 0.9; 95% CI = 0.4–1.5; P < 0.01) and %CD90+ (beta-coefficient = 0.4; 95% CI = 0.2–0.6; P < 0.001) after adjustment for covariates.