The comparison of predictive value of cervical length in singleton spontaneous preterm labor with in vitro fertilization pregnancies: A cohort study

Preterm labor (PTL) is one of the most important factors in neonatal mortality. Some studies have revealed a reverse relationship between cervical length (CL) and PTL, however, further evidence is needed to confirm it.

To investigate the predictive value of CL in spontaneous and in vitro fertilization (IVF) pregnancies.

This prospective cohort study was performed on 154 pregnant women from 16-26 wk of gestation with singleton fetus in spontaneous delivery (n = 77) and IVF pregnancies (n = 77) and followed up until delivery. Women with multiple pregnancy, placenta previa, cerclage, and congenital anomalies were excluded from study. The cut-off determination was done according to the Roc analysis.

The mean CL in term delivery and PTL groups were 37 ± 7 mm and 31 ± 6 mm, respectively (p < 0.001). The frequency of PTL in spontaneous and IVF pregnancies were 7.8% and 23.27%, respectively (p = 0.007). According to the Roc analysis, the best cut-off for normal pregnancy was ≤36 mm with the negative predictive value of 97.9%, the positive predictive value of 11.4%, sensitivity 83.3%, and specificity of 46.5%. While for the IVF group, the cut off was ≤30 mm, with a negative predictive value of 88.4%, positive predictive value of 57.8%, sensitivity of 63.2%, and specificity of 86%.

In this study, IVF had a significant direct correlation with PTL. CL also had a significant indirect relationship with PTL.