Hayashi M et al. - Tumor necrosis factor-alpha (TNF-alpha) is present in human placental and uterine cells and promotes the regulation of trophoblast growth and invasion. Tumor necrosis factor receptor 1 (TNF-R1) is a receptor for TNF-alpha, and soluble TNF-R1 (sTNF-R1) is present in amniotic fluid after receptor shedding.