Asymptomatic short cervix and threatened preterm labor: A comparative study on perinatal outcomes

Objective

To determine the rate of delivery within 15 days of admission among patients with an asymptomatic short cervix (ASC) compared to those admitted for threatened preterm labor (TPL).

Material and methods

This retrospective study conducted in a tertiary maternity hospital, included patients with a singleton pregnancy admitted with a cervical length of less than 25 mm between 24 and 34 weeks. The population was divided into two groups, patients with ASC (i.e., with no contractions at admission) and patients with TPL. The primary outcome was the delivery rate within 15 days of admission. Secondary outcomes included gestational age at delivery, preterm delivery rate before 37°^/7 weeks and before 34°^/7 weeks, admission to delivery interval, 5 min Apgar score and transfer to neonatal intensive care unit rate. The characteristics of the two groups and the primary and secondary outcomes were compared between the two groups using univariate analysis. Two subgroup analysis were performed, one restricted to patients with a mildly modified CL (15 ≤ CL < 25 mm), and one excluding patients at high risk of preterm birth.

Results

Among the 247 included patients, 136 (55.1 %) had TPL, and 111 (44.9 %) ASC. There were no significant differences in the rate of patient who delivered within 15 days of admission between the groups, 13.2 % in the TPL group vs 8.0 % in the ASC group (p = 0.22). Patients in the TPL group had a significantly higher frequency of delivery before 34 weeks compared to those in the ASC group (19.9 % versus 9.0 %, p = 0.02 This finding persisted in the subgroup analysis excluding patients at high risk of preterm birth (16.5 % in the TPL subgroup vs. 6.9 % in the ASC subgroup, p = 0.04). There were no significant differences in the rates of preterm delivery before 37 weeks, the admission-to-delivery interval, or neonatal outcomes between the two groups or within the subgroup analyses.

Conclusion

The frequency of delivery within 15 days of admission was not statistically different between patients with an asymptomatic short cervix and those with TPL. Nevertheless, these asymptomatic patients delivered significantly later and less frequently before 34 weeks, with only one in ten requiring corticosteroids.