Raba and Tabarkiewicz showed that the level of cytokines influences PTB. Moreover, an algorithm based on the measurement of selected cytokines’ concentration might help predict PTB[22]. Multiple studies describe CB2 modulating influence the release of the cytokines[23–26]. Moreover, CB can be stimulated a number of cytokines (IL-1, IL-4, IL-10, IL-6, TNF-a, IL-8, MIP-1(CCL3 and CCL4), RANTES(CCL5))[23, 27–30]. Further studies are needed to establish the exact correlation between cytokines and CB2 stimulation in pregnant women. The endocannabinoid system modulates the action of leukocytes by stimulating the CB2 presented on leukocyte cells[31], which in turn inhibits the inflammatory response[32]. This observation was also made intrauterine in patients with adenomyosis[33, 34]. PTB might be associated with inflammation caused by intraamniotic infection[35], but inflammation as an origin of physiological delivery takes place without infection[4, 32]. Inflammation could be initiated by a decrease in the expression of CB2 in the placenta, leading to a complete loss of the receptors[26]. Stimulation of the CB2 during pregnancy could be responsible for pregnancy tolerance[36]. However, further studies are needed to confirm this hypothesis.