TNF and bronchopulmonary dysplasia: According to the current study and previous observation (27) demonstrating that proinflammatory cytokines scarcely pass through the placenta, maternal serum levels of IL-6, IL-8, TNF-α, and IFN-γ are not increased in preterm infants, suggesting that maternal inflammation status has limited predictive value for intrauterine infection and the development of BPD.