n. a large glycoprotein that acts as a host defence mechanism. In the plasma it induces phagocytosis and on the cell surface it induces protein linkage which is important in the formation of new epithelium in wound healing. It is also involved in platelet aggregation. It is concentrated in connective tissue and the endothelium of the capillaries and is a component of the extracellular matrix. In pregnancy, fetal fibronectin (fFN) is found in high concentrations in secretions from the cervix and vagina before fusion of the membranes occurs at around 21 weeks of gestation. Inflammation or trauma to the fetal–maternal surface after then causes secretion of fFN into the cervix and vagina. Vaginal swabs that detect fFN can be used to predict preterm birth between 22 and 34 weeks gestation.
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