Objective:

To determine the cervical length in the second trimester that best predicts the development of spontaneous preterm delivery in pregnant women treated at the University Hospital of Coro for the period January-August 2025.

Methods:

A prospective, observational, and descriptive study was conducted, including a sample of 335 pregnant women. Cervical length was measured during the second trimester and correlated with the occurrence of preterm delivery.

Results:

The mean cervical length was 29.68 ± 2.42 mm (range: 24 mm to 34 mm). Eighty women (23.9%) had a spontaneous preterm delivery. Four underweight women had a preterm delivery, representing 1.2% of the total sample and 15.4% of all underweight participants. Meanwhile, 16 obese pregnant women had a preterm delivery, representing 4.8% of the total sample and 69.6% of all obese participants. According to the Receiver Operating Characteristic (ROC) curve and Youden’s index, the cervical length value that predicts spontaneous preterm delivery with the highest sensitivity and fewest false positives was 27.50 mm. At this threshold, sensitivity was 78.8%, specificity was 99.6%, the positive predictive value was 98.4%, and the negative predictive value was 93.7%. The calculated relative risk (risk index) was 15.69.

Conclusions:

The cervical length that best predicts the occurrence of preterm delivery is 27.5 mm; A patient with a cervical length of less than 27.50 mm has approximately 16 times the risk of having preterm delivery than those patients with higher values.