OBJECTIVE: We determined the value of cervical examination and tocodynamometry in identifying nulliparous women at risk for spontaneous preterm delivery. STUDY DESIGN: At 27.5 +/- 0.8 weeks' gestation 589 women underwent 30 minutes of tocodynamometry, and 570 of these had a cervical examination. Positive findings on these examinations were compared to the rate of spontaneous preterm delivery, defined as those deliveries following the onset of spontaneous labor or premature rupture of membranes. RESULTS: The two best predictors of spontaneous preterm birth were two or more contractions in 30 minutes and the presence of a soft or medium consistency on cervical examination. As the contractions increased from zero to four or more, the rate of spontaneous preterm delivery rose from 4.2% to 18.2%. CONCLUSION: In nulliparous women at 28 weeks' gestation, uterine contractions and several components of the cervical examination predicted spontaneous preterm birth.