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

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.