Little is known regarding the regulation of the timing of parturition. Recent evidence suggests an interaction between the immune system and uterine contractility in late gestation.
 Pregnant rats were treated with LPS in vivo in attempts to establish a model of premature parturition induced by the pro‐inflammatory response. Uterine explants were incubated in vitro to determine the effects of IL‐6 on uterine synthesis of oxytocin (OT) and its receptor (OTR).
 LPS injection was quite toxic to pregnant rats and gave extremely variable results. In animals that delivered, there was a marked increase in the uterine concentrations of OTR and OTR mRNA. There was no consistent effect regarding the timing of parturition. IL‐6 caused a significant increase in the concentration of OTR mRNA in uterine explants from pregnant rats but not in tissues from non‐pregnant animals.
 Rat uterine concentrations of OTR are regulated by IL‐6. Pro‐inflammatory cytokines may stimulate uterine contractility in late gestation rat uterine tissues through a mechanism involving stimulation of OTR.