A comparative study of shear wave elastography on preterm birth risk in women with natural pregnancies and in vitro fertilization embryo transfer pregnancies.

Background: Shear wave elastography (SWE) can evaluate cervical function by measuring the stiffness of the cervix of pregnant women. The aim of this study was to investigate the value of transvaginal ultrasound real-time SWE for assessing cervical elasticity in different modes of conception for the prediction of preterm birth. Methods: This prospective study included 100 women with in vitro fertilization embryo transfer (IVF-ET) singleton pregnancies at 16-28 weeks of gestation. A total of 150 women who conceived naturally constituted the control group. Basic data, pregnancy complications, pregnancy outcomes, and ultrasound measurements, including the cervical length (CL), the uterocervical angle (UCA), and Young's modulus values of cervical duct elasticity, were compared between the two groups. Predictors of preterm birth were analyzed according to pregnancy outcomes, a binary regression model was constructed with significant variables to analyze the predictive value of multiple factors for spontaneous preterm birth (SPB) in different pregnancy modes, and the predictive value of the regression model was evaluated using receiver operating characteristic (ROC) curves. Results: In the comparison of the two groups of cases in this study, the Young's modulus value of cervical elasticity measured by ultrasound in the IVF group was higher than that in the natural pregnancy group, and there was a statistically significant difference between the two groups (P<0.05). The CL and elastic Young's modulus values of the upper lip of the endocervical os (point A) were lower in preterm patients than those in full-term patients in both groups. The rate of endocervical opening was higher in preterm patients than it was in full-term patients. There was a statistically significant difference between preterm patients and full-term patients (P<0.05). A multifactorial logistic regression model revealed that the endocervical os morphology, CL, and mean value of elastic Young's modulus of the upper lip of the endocervical os (point A) were independent factors affecting the occurrence of preterm birth in different modes of conception, with complete closure of the endocervical os, a long CL, and a large value of the Emean of point A being protective factors for preterm labor. Point A Emean values <15.3 kPa in the natural pregnancy group and <14.7 kPa in the IVF-ET group resulted in an increased risk of preterm birth. Conclusions: Real-time SWE measurement of Young's modulus of cervical duct elasticity in pregnant women with different modes of conception is valuable for predicting spontaneous preterm birth, and a combined prediction model consisting of elastic Young's modulus values of the upper lip of the endocervical os (point A) together with the CL and endocervical os morphology is even more valuable for predicting spontaneous preterm birth in pregnant women who underwent IVF-ET.