Elevated plasma interleukin 6: a biochemical marker of human preterm labour.

Maternal peripheral venous plasma interleukin 6 (IL-6) concentrations were determined during human pregnancy and labour at term and preterm. During preterm labour, IL-6 concentrations were significantly elevated (p < 0.02) compared to gestationally matched, non-labouring controls (53.7 +/- 15.7 pg/ml, n = 17, and 15.4 +/- 6.4 pg/ml, n = 23, respectively). IL-6 concentrations did not vary significantly during normal pregnancy and labour at term. These data support a role for IL-6 in the pathogenesis of human preterm labour, are evidence for the contention that preterm labour is mechanistically distinct at a biochemical level from normal labour at term and identify maternal peripheral venous plasma IL-6 as a biochemical marker of this condition.