Pregnant women with bacterial infection had significantly higher serum levels of TNF‐α than those with influenza A infection (0.46 vs. 0.38 pg/mL; P = 0.012), but no significant differences were observed in IL‐2, IL‐4, IL‐6, IL‐10 or IFN‐γ (2.36 vs. 2.29, 2.30 vs. 2.28, 7.13 vs. 5.08, 1.12 vs. 1.20 and 3.77 vs. 3.92 pg/mL; P > 0.05), as shown in Figure 2. Here, TNF is linked to bacterial infectious disease.