Can sonographic changes in cervical length during pregnancy predict the need for cervical ripening in term pregnancies?

Abstract

Purpose: To evaluate the effect of changes in sonographic cervical length (CL) measured at 14-16 and 21-24 weeks of gestation, on cervical ripening in term pregnancies.

Methods: This retrospective, cohort study included term pregnancies with CL measured with transvaginal sonography (CL₁ at 14-16 weeks gestation and CL₂ at 21-24 weeks). History of preterm labor, multiple gestations, planned caesarean section, fetal anomalies and stillbirths were excluded. Participants were grouped based on ≥ 10% vs. < 10% CL shortening between measurements. The primary outcome was whether cervical shortening < 10% between CL₁ and CL₂ was associated with increased use of cervical ripening. Secondary outcomes were gestational age at delivery, delivery mode and birthweight.

Results: Among 267 women who met the inclusion criteria, CL decreased ≥ 10% between scans in 70 (26.3%) and < 10% in 197 (73.7%). Baseline characteristics were similar between groups. Fewer women with ≥ 10% shortening between scans, underwent cervical ripening (7.1% vs. 16.8%, p < 0.05). In addition, in the ≥ 10% group, although CL₂ was in the normal range, it was shorter than in the < 10% group (34.3 ± 6.7 mm vs. 40.1 ± 6.4 mm, p < 0.01).

Conclusion: Decrease in cervical length > 10% between 14-16 and 21-24-weeks' gestation is associated with lower use of cervical ripening at term.

Keywords: Cervical length measurement; Cervical ripening; Cervical ripening at term.