Objective: To determine the optimal value of cervical length and the presence of funneling in women with preterm labor to predict preterm delivery.
Material and Method: Transvaginal sonography to determine cervical length and presence of funneling in 69 pregnant women with gestational age between 24 – 36 weeks who had preterm labor and were admitted to the labor room of BMA Medical College and Vajira Hospital.
Results: The cervical length of women with preterm labor ranged between 10.7–61.2 mm (mean + SD = 30.1 + 9.9 mm). The prevalence of preterm delivery was 43.4 %. The cervical length of 30 mm had the highest diagnostic performances in predicting preterm delivery, with the sensitivity 93.3 %, specificity 82.0 %. About 90% of women with funneling presence had preterm delivery.
Conclusion: The cervical length and presence of funneling in preterm labor women are significantly associated with preterm delivery.

Keywords: Preterm labor, Preterm delivery, Cervical length, Funneling, Transvaginal sonography