IL18 and hydrops fetalis: Among these mechanisms, inflammation plays a pivotal role in the evolution of HF, which is mostly mediated by several pro-inflammatory cytokines, such as increased levels of tumor necrosis factor-α (TNF-a), interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-10 (IL-10), interleukin-17 (IL-17), interleukin-18 (IL-18) and reduced concentrations of interleukin-5, (IL-5), interleukin-7 (IL-7), and interleukin-33 (IL-33) [6,7].