The Predictive Value of Cervical Length During the Second Trimester for Non-Medically Induced Preterm Birth

The aim of the present study was to investigate the predictive value of transvaginal ultrasonography measurement of cervical length (CL) during the second trimester for spontaneous preterm birth.

Data from 1222 women with a single fetus pregnancy, who delivered at our hospital between March 2019 and May 2020, were retrospectively analyzed. CL was measured during the second trimester, with a length of <25 mm regarded as cervical shortening. The relationship between CL, cervical shortening, and pregnancy outcome was analyzed.

The incidence of spontaneous preterm birth and cervical shortening in the 1222 women was 7.3% (89/1222) and 0.33% (4/1222), respectively. The average CL during the second trimester was 37.9 ± 5.7 mm for the spontaneous preterm birth group and 39.3 ± 3.8 mm for those who gave birth at full term. Three of the four cases of cervical shortening resulted in a spontaneous preterm birth. This showed a predictive sensitivity of 3.33% and a specificity of 99.9%.

CL measurement during the second trimester can be used as a routine test to predict spontaneous preterm birth. During the second trimester, the distribution of CL in women with single fetus pregnancies in China is different compared with other countries. Reducing the threshold of CL may improve the predictive value for preterm birth.