Relationship between preterm labor and the length of the cervical canal

To determine the relationship between cervical length at 16 and 24 weeks of gestation and the occurrence of preterm labor.

A prospective cohort study was performed on 153 pregnant women in two groups (75 and 78 person) after measuring cervical length with vaginal sonography. We calculated the incidence preterm labor m both groups, plus the sensitivity, specificity, positive and negative predictive values for cervical length.

The incidence of preterm labor was 17.3% ( 13/75) in the group with cervix length of less than 35 mm and 6/4% (5/78) in the group with cervical length ;::JS mm. The relative Risk was 2.7 (95% CI=l.3-4.5). Sensitivity, specificity, positive and negative predictive value of cervical length on preterm delivery with a cut-off point of 35 mm were 72%, 54%, 17% and 93% respectively. In the multivariate analysis of job, education, parity, gravidity and cervical length only cervical length was significantly related to preterm delivery (P<0.01). The cervical length also had a significant correlation with preterm delivery (P<0.001, r =0.61).

Cervical length between 16 and 24 weeks of gestation is a strong-predictor of preterm labor.