Background: Preterm delivery is a relevant public health problem since it is an important factor determinant of morbidity and the main reason for neonatal mortality. Many publications have pointed at clinical methods, biological, biochemical and ultrasonographic markers, which applied in combination or on their own, aim at predicting spontaneous preterm delivery. Transvaginal sonography is an effective method for the study of uterine cervix during pregnancy since it permits to assess the cervical morphology and biometry in detail with a high degree of reliability. The aim of this study was to evaluate the association between spontaneous preterm delivery (SPTD) before 35 and 37 weeks of gestational age, in high risk population and the measurement of the cervix length and cervical funneling.

Methods: A prospective cohort of 200 women carrying high risk pregnancies were evaluated by transvaginal sonography between 14th and 28th weeks of gestation.
Results: Cervical length less than 18mm before 35th and 37th weeks of gestational age and the presence of cervical funneling presented a satistically significant association with spontaneous preterm delivery before 35 weeks. The cervical length with less 18 mm demonstrated a strong association with SPTD before 37 weeks (p<0.005; OR=92.15) and before 35 weeks' gestation (p<0.001; OR=32.33). The logistic regression analysis suggested the cervical length with less than 18mm as the only variable that revealed satistically significance association with SPTD.
Conclusion: The results seem to indicate that the assessment of cervical length is an important ultrasound marker for predicting spontaneous preterm delivery.