To evaluate the predictive value of cervical size change rate and morphological distribution detected by ultrasound in the second trimester of pregnancy for preterm delivery.

From June 2016 to June 2018, 300 pregnant women who underwent antenatal testing and gave birth in , the Integrated Traditional Chinese and Western Medicine Hospital of Wenzhou were selected in this research.The length, width and shape of cervix were measured by transvaginal color doppler ultrasonography at 14 and 28 weeks respectively.According to whether or not premature delivery occurred, they were divided into premature delivery group and full-term delivery group.The differences of cervical length, cervical inner mouth width, cervical length shortening rate, cervical inner mouth width increasing rate and cervical shape distribution between preterm and full-term pregnant women were compared, and the correlation between the above indicators and the occurrence of premature delivery were analyzed.

The length of cervix in the preterm delivery group [(21.41±6.28)mm] was significantly shorter than that in the full-term delivery group at 28 weeks of gestation [(34.17±5.76)mm](t=10.295, P=0.000), and the width of cervical inner mouth in the preterm delivery group [(9.54±2.57) mm] was significantly longer than that in the full-term delivery group [(4.06±0.91)mm] (t=25.416, P=0.000). The shortening rate of cervical length [(39.28±8.65)%] and the increasing rate of cervical width [(149.74±15.09)%] in the preterm pregnant women during the second trimester were significantly higher than those in the full-term pregnant women [(10.15±5.29)% and (16.33±3.84)%] (t=21.471, 39.420; P=0.000, 0.000). The proportion of T-type cervix in the preterm delivery group (77.17%) was significantly higher than that in the full-term delivery group (63.28%) (χ²=10.935, P=0.001). According to the correlation analysis, the length of cervix was negatively correlated with premature birth (r=-0.612, P=0.035), and the width of cervical inner mouth, the shortening rate of cervical length in the second trimester and the increasing rate of cervical inner mouth width in the second trimester were positively correlated with premature birth (r=0.743, 0.665, 0.807; P=0.013, 0.026, 0.004).

Ultrasound monitoring of cervical size change rate and cervical morphology during the second trimester of pregnancy is helpful to the early prediction of preterm labor, which should be paid attention to clinically.

Pregnancy trimester, second; Premature birth; Ultrasonography, doppler, color; Cervical length measurement; Prenatal diagnosis