IL1B and hydrops fetalis: Increased vagal tone was correlated with the decreased level of inflammatory cytokines in plasma on the entire postoperative period (HF with TNF-α: r = −0.775, p = 0.001; HF with IL-1β: r = −0.856, p = 0.001; HF with IL-6: r = −0.888, p = 0.001).