TNF and immune system disorder: In pregnancy, a normal physiological concentration of TNF-α is beneficial to the pregnancy, but excessive secretion of TNF-α will cause the maternal–fetal interface immune disorder, such as T helper cell 1/T helper cell 2 (Th1/Th2) imbalance, macrophage changes and enhanced natural killer (NK) cell killing ability, eventually resulting in abortion, premature delivery and other adverse pregnancy outcomes [27].