EP18.04: Spontaneous preterm birth and cervical length in a pregnant Asian population

Preterm birth (birth before 37 weeks of completed gestation) is the leading cause of neonatal death, and has an incidence of 5-13% which is believed to be on the rise. The objective of this study was to determine the rate of spontaneous preterm birth and investigate the relationship between preterm birth and cervical length in a pregnant Asian population. 1000 women with single viable pregnancies at less than 14 weeks of gestation were recruited between September 2010 and November 2013. Cervical length was measured using ultrasound at each of the 4 antenatal visits (Visit 1: > 14 weeks, Visit 2: 18-22 weeks, Visit 3: 28-32 weeks and Visit 4: > 34 weeks) using the Fetal Medicine Foundation protocol. There was a significantly shorter cervical length both in the 2nd trimester (18 to 22 weeks) and the 3rd trimester (28 to 32 weeks) in the preterm birth group compared to the term birth group (p = 0.028 and p < 0.001 respectively). In the first trimester (11 to 14 weeks), there was no statistically significant difference in cervical length between the two groups (p = 0.425). ROC curve analysis for cervical length in the preterm birth group for Visit 2 and 3 showed an AUC of 0.605 and 0.725 respectively. At Visit 3, a cut-off level at 2.49 cm has a sensitivity of 54.8%, specificity of 82.5%, negative predictive value of 97.9% and positive predictive value of 11.1%. There is a significantly shorter cervical length in the 2nd and 3rd trimester in the preterm birth group. Cervical length is a moderate predictor of preterm birth with good negative predictive value and a relatively good specificity. Ultrasound cervical length screening between 28 and 32 weeks of gestation with a cut-off of ≥ 2.5cm can help to rule out likelihood of preterm birth.