TNF and bronchopulmonary dysplasia: Previous studies have confirmed an association of elevated levels of pro-inflammatory cytokines (interleukin 6 [IL-6], tumor necrosis factor-alpha [TNF-α], IL-1β, and IL-8) in amniotic fluid 5 days preceding delivery with the development of BPD, suggesting that the mechanism responsible for BPD may begin before birth [29].