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


Background: 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.

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

Materials and Methods: This prospective cohort study was performed on 154 pregnant women from 16-26 wk of gestation with a 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 the study. The cut-off determination was done according to the Roc analysis.

Results: 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%, a positive predictive value of 57.8%, sensitivity of 63.2%, and a specificity of 86%.

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

Key words: Cervix, IVF, Preterm delivery, PTL.

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