Aims: To determine the concentrations of tumor necrosis factor alpha, interleukin-1 beta, interleukin-6, and interleukin-8 in the lower uterine segment during preterm parturition.
Methods: In 71 patients who delivered prematurely by non-elective cesarean tissue specimens were obtained from the lower uterine segment. The patients were grouped in relation to the stage of cervical dilatation (< 2 cm, 2- < 4 cm, > or = 4 cm), duration of labor (< or = 6 h, > 6-12 h; > 12 h), and parity (1 versus > 1). Cytokine concentrations in protein extracts of the tissue samples were measured using enzyme-linked immunosorbent assays.
Results: Median concentration of tumor necrosis factor alpha did not change, but that of interleukin-1 beta, interleukin-6, and interleukin-8 were significantly higher at 2- < 4 cm than at < 2 cm cervical dilatation (6.6, 67.7, and 125.8 versus 1.1, 17.6, and 22.2 pg/mg protein, respectively). The concentrations of interleukin-6 and interleukin-8 showed a further increase at > or = 4 cm (297.2 and 468.6 pg/mg, respectively), but for interleukin-1 beta a decrease was observed (0.6 pg/mg). Cytokine concentrations were not related to duration of labor or parity.
Conclusions: Local inflammation-associated changes that are mainly related to the stage of cervical dilatation and to only a minor degree to uterine activity may play a crucial role in preterm parturition.