A G2P2 patient at 32 weeks' gestation enters at the triage unit complaining of frequent uterine contractions.
Her pregnancy history involves a 34-week premature birth.
The nurse does electronic fetal monitoring and takes a detailed history before evaluating her.
The patient reports no bleeding or membrane rupture.
She hasn't had a vaginal examination or sexual activity in over 24 hours.
In this case, the biochemical marker effective for predicting premature delivery is:
