Postpartum cervical length predicts subsequent preterm birth

Postpartum cervical length measurements help pinpoint which patients are at heightened risk of subsequent spontaneous preterm birth, as reported in a study.

In the 5-year prospective cohort study, researchers measured the mean cervical length in women who had given birth at either term or preterm (phase I). The measurements were taken at 8, 24 and 48 hours, and 6 weeks postpartum. All women were followed in their subsequent pregnancies to evaluate the gestational age at subsequent delivery (phase II).

The phase I analysis included 1,384 women. The cervical length was significantly shorter in the group of women with preterm birth (<34 weeks of gestation) than in the group of those who delivered at term; this was true for cervical length measurements taken 8 hours postpartum (mean, 8.4 vs 22.3 mm; p<0.0001), 24 hours postpartum (mean, 13.2 vs 33.2 mm; p<0.0001), and 48 hours postpartum (mean, 17.9 vs 40.2 mm; p<0.0001).

There was no significant difference in mean cervical length postpartum between the preterm and term birth groups at 6 weeks postpartum.

Meanwhile, the phase II analysis included 891 women. Compared with a history of spontaneous preterm birth, a short cervix postpartum performed better at detecting the risk of subsequent preterm birth (area under the curve [AUC], 0.66, 95 percent confidence interval [CI], 0.63–0.69 vs 0.57, 95 percent CI, 0.54–0.61; p<0.0001).

Of note, the predictive performance of a short cervix postpartum improved when combined with a history of spontaneous preterm birth (AUC, 0.74, 95 percent CI, 0.73–0.84; p<0.0001).

The findings highlight the potential benefit of considering an increased follow-up regimen and earlier interventions in women with a short cervical length postpartum to reduce adverse perinatal outcomes.