In this study, we established a positive correlation between the expression of the CBR in the analysed postpartum human placental tissues and PTB. First of all, we confirmed that CBRs were present in the placental tissue after delivery. Moreover, we demonstrated a significant decrease in the expressions of the CBR1, CBR1a and CBR2 in the placentas obtained from women after preterm deliveries, compared to placentas from women after term deliveries, suggesting a potential role of the receptors in the mechanisms leading to PTB. Last but not least, a negative correlation occurred between pregnancy duration and the CBR2, perhaps due to the two main effects of CBRs, i.e., their impact on muscle tissue and their role in inflammatory processes.