How you prepare

To avoid a false-positive result, the test will be done before any pelvic exam or transvaginal ultrasound. These tests can cause a release of fetal fibronectin and lead to a false-positive result. Intercourse and vaginal bleeding can affect the test results, too. If you experience vaginal bleeding or have had sex within the last 24 hours, the test probably won't be done.

Also, avoid using douches or lubricants or placing medications in your vagina shortly before the test. They also can affect test results.