Percentages of cervico-vaginal fluid samples with cytokine concentrations above the limit of detection for each biomarker for cases and controls between 16 and 24 weeks of gestation.

Samples with values below the limit of detection were included in all data analysis using interval regression (see methods). Interleukin (IL)-1β, IL-4, IL-6, IL-7, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon (IFN)-γ, monocyte chemotactic protein (MCP)-1, macrophage inflammatory protein (MIP)-1β, tumour necrosis factor (TNF)-α.