Effect of sexual intercourse on fetal fibronectin concentration in cervicovaginal secretions.

An investigation was performed evaluating persistence of fetal fibronectin in cervicovaginal secretions after sexual intercourse. Fetal fibronectin samples were positive at 12 to 24 hours, 24 to 48 hours, and 48 to 72 hours after coitus in 22.2%, 11.8%, and 5.6% of samples, respectively. A history of vaginal intercourse should be obtained before sampling for fetal fibronectin to eliminate this potential source of false-positive fibronectin test.