CCL2 and preterm premature rupture of the membranes: Another less studied mechanism is related to the abnormal regulation of NK cells by natural cytotoxicity receptors, which regulate NK cell cytotoxicity and cytokine production or the activation of decidual macrophages by MCP-1 and other profiles of cytokines such as the Th-17 profile, which have been implicated in APO such as PTB and PPROM (Fukui et al., 2009; Bardou et al., 2014; Liu et al., 2017b).