The Role of Uterocervical Angle on Preterm Birth Incidence

Background: Preterm birth (PB) is associated with significant morbidities in surviving infants. Accurate prediction of PB is essential for effective prevention and management. Continuous monitoring of cervical parameters has shown utility in several studies. Objectives: This study aimed to investigate the role of the anterior uterocervical angle (UCA) in predicting the incidence of PB. Methods: A prospective, descriptive-analytic study was conducted with 165 pregnant women referred to the prenatal care clinic at Yas Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran, in 2021 - 2022. Participants were selected through convenience sampling. Cervical parameters, including UCA, length, and width, were measured via vaginal ultrasound during each trimester. All women were followed until delivery to determine PB incidence. Data were analyzed using descriptive and analytical statistical tests, including the chi-square or Fisher’s exact test and the independent samples t-test or Mann-Whitney U test. Results: Among the participants, 12 (7.3%) experienced preterm delivery. Cervical length was significantly shorter in women with PB during the second trimester (32.58 ± 4.77 mm vs. 34.68 ± 3.80 mm, P = 0.042) and third trimester (30.00 ± 4.74 mm vs. 32.77 ± 3.88 mm, P = 0.022). The mean UCA in women with preterm delivery was higher than in those with term delivery during both the second (90.58 ± 17.21° vs. 88.66 ± 16.76°) and third (100.25 ± 14.56° vs. 98.89 ± 17.78°) trimesters (P > 0.05). A UCA greater than 105° in the second trimester had a sensitivity of 16.7% and specificity of 81.5% for predicting PB. In the third trimester, a UCA greater than 105° showed a sensitivity of 58.3% and specificity of 60.7% for predicting PB. Conclusions: This study emphasizes the importance of regular cervical parameter measurements throughout pregnancy. A UCA greater than 105° in the third trimester appears to be a potential predictor of PB.