Objective: The purpose of this study was to investigate the changes in the level of fetal fibronectin in amniotic fluid during the course of pregnancy.
Method: Amniotic fluid samples were obtained from 74 women whose pregnancies ranged in gestation from 14 to 38 weeks. Fetal fibronectin in amniotic fluid was examined with a sensitive immunoassay using a monoclonal antibody FDC-6 which recognizes a unique epitope (III-CS) of the molecule.
Results: Fetal fibronectin levels in amniotic fluid decreased significantly during pregnancy (r = -0.79, P < 0.0001). The mean levels at less than 20 weeks of gestation were significantly higher than those at 20-29 weeks (P < 0.0001) and at 30 weeks to term (P < 0.0001).
Conclusion: These results must be considered when fetal fibronectin in vaginal fluid is used as an indicator of the rupture of membranes.